PHOTOPTICS 2019 Abstracts


Area 1 - Lasers

Full Papers
Paper Nr: 24
Title:

Optical Bistability in Monolithic Two-sectioned InAs/InP Quantum-dash Laser

Authors:

E. Alkhazraji, Mohd S. Alias and M. M. Khan

Abstract: Observation of optical bistability in a two-section InAs/InP quantum dash laser is reported. The hysteresis in the optical power-injection current (L-I) characteristics is found to vary with the absorber reverse bias condition. A reverse bias of −0.8 (0) V to the saturable absorber, a hysteresis of 32 (24) mW is measured when the injection current through the gain section is swept forward and backward. Moreover, the bistability is further affirmed through investigation of the lasing emission spectra at specific operating points.

Paper Nr: 28
Title:

A Coincidence Counting System for Twelve-photon Entanglement Experiment

Authors:

Yi Hu, Wei Li, Yue-Fei Wang, Ge Jin and Xiao Jiang

Abstract: Multi-photon entanglement is an important resource for photonic quantum information, and its scale has reached 6 photons with 18 qubits or 10 photons with 10 qubits. The upcoming challenge will be 12 photons with 12 qubits. In the entanglement experiments of such a plurality of photons, the coincidence counter has always been an important tool, and the experiment of 12 photons poses new requirements. Here we report the upgrading of a coincident counting system that worked well in 6-photon and 10-photon experiments to the coming 12-photon one. The scalability of the coincident counting system has been shown. By optimizing the logic in the Field Programmable Gate Array(FPGA) and the LabVIEW program, not only the number of input channels has been increased for 12 photons, but also the functions of signal alignment and status monitoring have been improved. The coincidence result can be analysed both in real-time and off-line. The system is capable to extend to 104 channels at most for channel consuming application.

Short Papers
Paper Nr: 36
Title:

Quantum Bit Error Rate Analysis of the Polarization based BB84 Protocol in the Presence of Channel Errors

Authors:

Ágoston Schranz and Eszter Udvary

Abstract: In the BB84 quantum key distribution (QKD) protocol, the communicating parties do a quantum bit error rate (QBER) test to determine whether there is an eavesdropper trying to gain information about the secret key. However, the QBER is not only influenced by the eavesdropper’s strategies, but also by the imperfections of the physical devices and the channel through which the quantum states propagate. We developed a simple channel model with error parameters describing the channel and the potential polarization switching in the transmitter, to see how those effects influence the QBER in a polarization-qubit BB84 implementation. Certain well-defined probabilistic channel models are compared to see which is responsible for the highest error probability.

Paper Nr: 60
Title:

Solar Pumped Lasers for Free Space Laser Communication

Authors:

Changming Zhao, Haiyang Zhang, Zhe Guan, Zitao Cai, Dongbing He and Yongheng Wang

Abstract: Solar Pumped Lasers (SPL) is a kind of lasers that can transform solar light into laser directly, with the advantages of least energy transform procedure, higher energy transform efficiency, higher reliability, and longer lifetime, which is suitable for use in unattended space system, for solar light is the only form of energy source in space. In order to exploring the possibility of using SPL for free space laser communication, multi-frequency SPL is investigated and solar pumped laser amplification is initiated. The first demonstration of SPL used in free space laser communication is also conducted in our group.

Paper Nr: 61
Title:

Experimental Implementation of Bias-free Quantum Random Number Generator based on Vacuum Fluctuation

Authors:

Ziyong Zheng, Yichen Zhang, Song Yu and Hong Guo

Abstract: We experimentally demonstrate a bias-free optical quantum random number generator with real-time randomness extraction to directly output uniform distributed random numbers by measuring the vacuum fluctuation of quantum state. A phase modulator is utilized in the scheme to effectively reduce the influence of deviations between two arms of the generator caused by the imperfect practical devices, which is an innovative solution in the field of quantum random number generator. In the case where the feedback modulation frequency is much faster than the phase jitter, an unbiased result can be obtained by an additional subtraction between the compensation signal and its average value to eliminate residual deviation. A following randomness extractor is applied to eliminate the influence of residual side information introduced by the imperfect devices in practical system.

Paper Nr: 64
Title:

Formation of Low Resistance Contacts to p-type 4H-SiC using Al-Film Source Laser Doping

Authors:

Kento Okamoto, Toshifumi Kikuchi, Akihiro Ikeda, Hiroshi Ikenoue and Tanemasa Asano

Abstract: Impact of laser doping on the formation of ohmic contacts to 4H-SiC has been investigated. The laser doping was performed by irradiating pulse-width stretched KrF excimer laser to an Al film coated on the surface of 4H-SiC. Doping and contact formation on the carbon face of 4H-SiC were investigated. The doping was carried out while keeping the sample at room temperature. It is found that the laser doping is able to introduce Al up to a concentration as high as 5×1021 cm-3. As a result of heavy doping, the contact made of Ti/Al metallization provides the ohmic contact whose specific contact resistance as low as 4.0×10-6 Ωcm2 without additional heat treatment. The specific contact resistance is lower than that reported for ohmic contacts formed by using ion implantation.

Paper Nr: 68
Title:

Laser Induced Breakdown Spectroscopy of Diesel Particulate Matter Exhaust Emissions Generated from on Road Diesel Engine: Light Duty Vehicles

Authors:

Richard Viskup, Christoph Wolf and Werner Baumgartner

Abstract: In this research we apply Laser Induced Breakdown Spectroscopy (LIBS) technique for high resolution spectrochemical analysis of Diesel Particulate Matter - DPM exhaust emissions. DPM has been collected from real, on road - Light - Duty Vehicles, driven by combustion Diesel engine. We have been concerned with the main chemical elements, presents in various type of real Diesel particulate matter. From LIBS measurements, it has been shown, that the plasma electron density can be use for the basic classification of different types of DPM matrices. The excitation temperatures of atoms and ions in plasma can be use for further quantitative analyses of diverse Diesel Particulate Matter. The aim of this study is to reveal the compounds, which are mostly dominant in the Diesel engine exhaust emissions and can affect the overall composition of the DPM. The presence of these elements in exhaust emission may point to different processes, mainly to fuel quality, insufficient engine combustion process, incomplete catalytic reaction, inefficient Diesel particulate filtering technique, or failure of the Diesel engine.

Paper Nr: 19
Title:

Study on Contamination Control of Optical Thin Films with First Contact TM

Authors:

Yan Baozhu, Yuan Shengfu, Zhou Qiong, Sun Quan and Yang Yi

Abstract: In high power laser system, it is very lethal of contamination on the surface of optical thin films. The contamination can be heated and burn rapidly under high power laser irradiation, which would result in damage to the optical thin films or even the whole optical component. Therefore, it is the key to control the contamination on the surface of optical thin films. First ContactTM can be used to clean the surface of optical thin films, remove fingerprints, dust and other contamination attached to the surface of optical thin films. It has been applied in many important projects such as aLIGO. In this paper, the First ContactTM was used to clean the optical thin films for chemical lasers. A microscope was used to test the appearance of the optical thin films before and after cleaning, which showed that, the First ContactTM is able to remove contamination, such as fingerprints and dust, attached to the surface of optical thin films for chemical lasers. The absorption coefficients of the optical thin films before and after cleaning were measured by an intra-cavity device, which is 286.5ppm and 216.9ppm respectively. The absorption coefficient was decreased by 24.3% after cleaning. The above results show that, the First ContactTM can effectively clean the optical thin films for chemical lasers, and there is no First ContactTM remain on the surface of optical thin films. It is found that the shortcoming of the First ContactTM is that, it cannot repair the defects in the substrates or optical thin films of the optical components, and cannot clean the optical thin films online. Finally, the use of First ContactTM was optimized, and the optimized method is conducive to the long-term preservation of optical components.

Paper Nr: 29
Title:

Modeling a Two-section Monolithic InAs/InP Quantum-dash Laser: Wavelength Tunability and Sharp Turn-on Characteristics

Authors:

M. M. Khan

Abstract: Rate-equation based numerical model for the analysis of two-section InAs/InP quantum-dash tunable laser is developed. The model takes into account quasi-zero dimensional density of states of dashes in the linear optical gain formulation besides incorporating both homogeneous and inhomogeneous broadening of the active region. The simulation results show a broad tunability of ~22 nm from longer 2000 µm device with 700 µm absorber length compared to 1000 µm device with 300 µm absorber length, which exhibited ~15 nm tuning window, in the L-band. Moreover, a sharp turn-on behavior is also observed, which is found to be in good agreement with our recent experimental results. Such devices and their comprehensive analysis would enable design optimization of two-section quantum-dash lasers, which are promising candidates as monolithic tunable lasers for next-generation access networks.

Area 2 - Optics

Full Papers
Paper Nr: 32
Title:

Research Progress of Tip/Tilts Control Bandwidth Promotion for Beam Combining Application in IOE, CAS

Authors:

Guan Huang, Feng Li, Chao Geng, Xinyang Li and Jiaying Liu

Abstract: Fiber-array beam director composed of numerous fiber collimators gives out excellent adaptive optics (AO) performance better than traditional AO-enhanced monolithic director owe to the extremely high bandwidth of the fiber-integrated phase modulator. For fiber laser transmission applications represented by coherent-beam-combining, correction of sub-aperture tip/tilts is needed to further promote the combined beam’s quality besides the phase-locking control. For power reception of the incident laser beam, tip/tilts control is indispensable to ensure efficient and stable laser beam coupled from space into fiber. Here, we adopt adaptive fiber optics collimator as the tip/tilts device, which owns advantages of precise control, small inertia and convenience for packaging. While most existed tip/tilts control methods are restricted to optimization algorithms which suffer from disadvantages of low bandwidth utilization ratio. In this paper, research progress of tip/tilts control bandwidth promotion for beam combining applications in IOE, CAS is presented. Methods of inherent response delay compensation and active resonance suppression are proposed and experimentally validated. The experimental results give great prospects to future applications that utilize fiber-collimators-array as optical transceivers.

Paper Nr: 34
Title:

The Stray Light Absorption and Anti-photobleaching Capacity of Matting Materials on Optical System

Authors:

Rou-Jhen Chen, Chun-Han Cho, Chia-Lien Ma, Liang-Chieh Chao, Kuo-Cheng Huang and Yu-Hsuan Lin

Abstract: Eliminating stray light is a very important item in optimizing optical systems. The typical method is to use matting materials to coat onto the optomechanical component. However, the material will deteriorate or bleaching after being exposed to long periods of time and high UV energy. The performance of the optical system will be therefore affected. In this study, the anti-photobleaching capacity of matting materials on various substrates was discussed. A high intensity UV source was used to radiate the samples for long time. The changes of the morphology and relative reflectance of sample were observed and analysed. Also, a 355 nm pulsed laser was used to perform the surface modification on samples. An improvement of the matting performance was expected. This study succeeded in establishing a comparing procedure, which enabled the characteristic comparison between the various experimental conditions. This study provides a useful database for the development of matting material technology.

Paper Nr: 35
Title:

Manufacturing of Cylindrical Micro Lenses and Micro Lens Arrays in Fused Silica and Borosilicate Glass using F2-Laser Microstructuring

Authors:

Sebastian Buettner, Michael Pfeifer and Steffen Weissmantel

Abstract: The results of our investigations on direct laser fabrication of cylindrical micro lenses and micro lens arrays in fused silica and borosilicate glass using fluorine laser microstructuring technique will be presented. The process, based on the mask projection technique, enables the generation of almost perfectly curved, smooth surfaces with a defined radius of curvature. In particular, it will be shown that one calculated mask can be used to generate different radii of curvature depending on the laser pulse fluence and the pulse-to-pulse overlap. The surface roughness of the lenses depends on the process parameters as well. To generate continuous transition areas between the lenses in one array, the optimal lens spacing was determined. Moreover, it can be shown, that the surface quality of cylindrical micro lens arrays, made of fused silica, can be improved by CO2 laser smoothing. The minimal reached surface roughness is 4.6 nm RMS.

Paper Nr: 46
Title:

Passive Path Imbalance Measurement in Fiber Optic Interferometer using Homodyne PGC Scheme

Authors:

Shubham Mirg and Pradeep K. K.

Abstract: We demonstrate a passive measurement technique for interferometer path imbalance using homodyne PGC. A 20.8 kHz frequency modulated optical source is employed to interrogate an unbalanced Michelson interferometer. The spectrum of the received photocurrent is then recorded for various frequency deviation values. The variation in harmonic peak powers enables us to determine path imbalances. Different path imbalances are estimated and verified against the pre-calibrated values. The measurement scheme proposed requires no feedback and can be employed to passively measure path imbalances in interferometer sensor arrays already laid out in the field.

Paper Nr: 57
Title:

Soldering and Packaging Study for an Optical Filter Required for High Resolution Earth Observation Space Missions

Authors:

Mariia Kepper, Pol Ribes-Pleguezuelo, Marcel Hornaff, Erik Beckert, Ramona Eberhardt, Pascal Pranyies, Isabelle Toubhans, Francis Descours and Andreas Tünnermann

Abstract: The goal of our study is to optimize the packaging process of an optical sensor module under the space mission requirements. The intention of the project is to develop a generation of optical sensor modules avoiding conventional organic adhesives (standard used technologies). The sensor module, designed by Sodern, consists of three parts: the sensor, the filter frame and the filter. The Solderjet Bumping is planned to be used for assembling KOVAR(29 % Ni, 17 % Co, 54 % Fe) and N-BK10 (Borosilicate-Kronglas, Schott glass) and for assembling KOVAR and KOVAR materials, chosen for this application, and creation of a strong bond between these materials, which should withstand the harsh environmental space conditions.

Short Papers
Paper Nr: 9
Title:

“Coherent Transitions” and Rabi-type Oscillations between Spatial Modes of Classical Light

Authors:

A. V. Bogatskaya, N. V. Klenov, A. M. Popov and A. T. Rakhimov

Abstract: In this paper we apply approaches and concepts from quantum mechanics to analyze the propagation of classical electromagnetic waves in the elements of integrated optical circuits. We consider here regions of transparent materials as potential wells between barriers of complex shape formed by opaque media. This allows us to build an analogy between coherent oscillations in a quantum system and the redistribution of the field strength of a classical wave in space in the framework of the slow-varying amplitude approximation for the wave equation. We also demonstrate the possibility of controlling the mode composition of a classical light in a spatially inhomogeneous waveguide structure. The proposed description is based on the analogy with Rabi-type oscillations in quantum mechanics.

Paper Nr: 10
Title:

Experimental Measurement of Angular Anisoplanatism for Sodium Laser Guide Star: Synchronized Range Gating Realization

Authors:

Xi Luo, Xinyang Li, Xiaoyun Wang and Kui Huang

Abstract: Laser Guide Star (LGS) is an ideal synthetic beacon of Adaptive Optics (AO) for compensating for the atmospheric turbulence induced wave-front distortion of the science object; however the unavoidable anisoplanatism resulting from different light experience between the LGS and the science object through turbulent atmosphere will lead to a degradation of compensation performance, especially for the angular anisoplanatism in sodium LGS AO. By using our developed Hartmann-Shack (HS) wave-front sensor with accurate range gating mechanism, the return-light spot arrays through turbulent atmosphere from the natural star and the excited sodium LGS with certain angular offsets can be synchronously collected. Different from our previously published work (Luo et al., 2018), the experimental set-up, the structural design of the range gating mechanism, and the timing design of the synchronized control are discussed emphatically in this paper. The typical experimental measurement result of the angular anisoplanatism for the sodium LGS with 10” angular offsets is just briefly presented, which is basically consistent with our previous numerical simulation result (Luo et al., 2015). The majority of Zernike-modal de-correlations between the sodium LGS and the science object occur obviously, as the sodium LGS reference moving outside of the optical path from the science object to the telescope aperture.

Paper Nr: 17
Title:

Microscale Optical Capture System for Digital Fabric Recreation

Authors:

Raúl Alcain, Carlos Heras, Iñigo Salinas, Jorge López and Carlos Aliaga

Abstract: Synthetic images are ubiquitous in the world, being extensively used in advertising, industrial design and prototyping. However, automatic digital reproduction of fabrics is still an open problem in industrial contexts, due to the inherent complexity of cloth appearance. We present a system to capture images of fabrics at micron resolution, lit from a set of collimated beams of LED luminaires distributed along the hemisphere. The system ensures plane wavefront with a 1:1 magnification while minimizing self-occlusions. It also allows for specular and diffuse light components separation through polarization, has a very accurate focusing system and a shallow depth of field for depth extraction. We demonstrate the system is suitable for later extraction of geometric and optical properties of the cloth at the fiber level, which is the main requisite for high fidelity photo-realistic cloth rendering.

Paper Nr: 25
Title:

Remote Over-saturation Amplification of Optical fiber Monitoring Pulses

Authors:

Breno Perlingeiro, Pedro T. Braga, Felipe Calliari, Guilherme P. Temporão, Gustavo C. Amaral and Jean P. von der Weid

Abstract: Optical fibers constitute a staggering portion of the physical layer underlying modern communication networks. To extend the reach of such networks around the globe, long-haul links are necessary. In this context, establishing a connection between two remote locations is only possible due to signal booster stations interspersed along the way. Supervision of such long distance links is of the utmost importance for their reliable operation. For multiplexed networks, high-ratio optical splitters are necessary to distribute the optical signal to multiple users, diminishing severely the transmitted power for each network. In this work, an automated signal boosting remote station for monitoring signals is presented. A Field Programmable Gate Array (FPGA) is part of the remote station and grants its autonomous operation. Making use of a topology capable of reaching over-saturation amplification of semiconductor optical amplifiers (SOA), a higher portion of the optical loss experienced in the splitter is precompensated in the remote node allowing for supervision reach-extension. Approximately 0.5 dB of increased dynamic range is experimentally achieved when comparing the proposed remote station with another one using the same optical amplifier. Even though the obtained extra gain is a minor improvement, the proposed topology paves the way for scalable amplification, allowing for longer reaches.

Paper Nr: 27
Title:

Light Fidelity (Li-Fi): Security and Market Sector

Authors:

Hikmatyarsyah, Sasono Rahardjo and Juliati Junde

Abstract: The increasing data traffic network is directly proportional to devices connected to the network. Visible Light Communication (VLC) systems such as Light Fidelity (Li-Fi) are not only promising solutions to overcome the limitations of Radio Frequency (RF), but will become a trend of wireless communication technology in the near future, especially indoor building solutions. VLC is inevitable from security challenges which is one of the main problems in communication systems even though the nature of the light itself cannot penetrate walls or enclosed spaces. This paper discusses the security protocol in the VLC system and describes its development especially for the indoor mechanism system. The paper also predicts the business market which will have the highest sector potential to implement the VLC system in the next few years. In conclusion, indoor buildings such as offices, malls and smart homes are the sectors that are most ready to adapt to the VLC system in the near future.

Paper Nr: 33
Title:

Study on Aging Effect of Optical Film under High Intensity of UV Exposure

Authors:

Fang-Ci Su, Hsin-Yi Tsai, Yu-Chen Hsieh, Chih-Chung Yang and Min-Wei Hung

Abstract: In the semiconductor industry, for lithography system the reflective film coated on the mirror and the anti-reflective film coated on the correction lens in the projection lens module were usually irradiated by the high intensity of I-line light, and the optical film will gradually age and become matte after using a period of time. In order to investigate the ingredient variation and aging effects of the optical film caused by i-line light, a UV light irradiation environment was built with an optical power of 80 mW. In the experiment, the reflective and anti-reflective film was coated on the BK-7 glass and irradiated by 24 to 120 hours. Then, the reflectivity/transmittance and the ingredient of optical film was measured and analyzed. The reflectivity and transmittance of optical film varied after 24 hour irradiation and decreased approximately 1.67 and 0.9 wt% after 120 hours irradiation, respectively. In addition, the results obtained from the focused ion beam (FIB) system indicated that the ingredient of oxygen of both films increased and the anti-reflective film ruptured evidently under 120 hours of irradiation. The results from the manuscript can serve as reference information for durability evaluation of optical film employed in the projection lens module in the semiconductor industry.

Paper Nr: 39
Title:

Rigorous Derivation of Temporal Coupled Mode Theory Expressions for Travelling and Standing Wave Resonators Coupled to Optical Waveguides

Authors:

Arezoo Zarif, Mohammad Memarian and Khashayar Mehrany

Abstract: Temporal coupled mode theory (CMT) has so far been applied phenomenologically in the analysis of optical cavity-waveguide structures, and relies on a priori knowledge of the to-be-excited resonator mode. Thus a rigorous derivation from Maxwell’s equations, and without any prior knowledge of the resonator type is needed. In this paper we derive temporal CMT of optical cavities coupled to waveguides. Starting from Maxwell’s equations and considering a proper expansion of the modes of the waveguide and resonator, and using mode orthogonality, the temporal CMT for this structure is obtained. We show that this formulation is general and can be applied to both traveling wave and standing wave type resonators. The results are validated against full-wave simulations.

Paper Nr: 40
Title:

A Digital in-line Holographic Microscope using Fresnel Zone Plate

Authors:

Yonghao Liang, Yilei Hua and Changqing Xie

Abstract: A digital in-line holographic microscope is presented using Fresnel zone plate. The light impinging on the Fresnel zone plate is divided into a number of diffraction orders. We use the 0rd light, which propagate along the original direction, as the reference beam. And the first order focus is used as a virtual point source after which the sample is placed. The light transmitted through the sample is scattered by the object and the structure information is carried by the light. The interference fringes created by the first and zero order diffraction are recorded by a digital camera. Afterwards, the object information is retrieved using reconstruction algorithm. With the aid of the Fresnel zone plate, an image with higher lateral resolution and lower noise could be obtained. This holographic microscope is tested with several samples and the results show that the lateral resolution is good, and for the phase object, the measured phased difference is accurate compared with the AFM test result.

Paper Nr: 44
Title:

Holistic Excitation of a Grating-coupled Waveguide at the Inner Wall of a Glass Tube

Authors:

Erika Koussi, Hugo Bruhier, Isabelle Verrier, Colette Veillas, Thomas Kampfe, Nicolas Crespo-Monteiro, Damien Jamon, Olivier Parriaux and Yves Jourlin

Abstract: This study presents a miniaturized silica tube, coated with a dielectric TiO2 sol-gel layer and a complementary positive photo resist periodically patterned in its inner walls. A cylindrical subwavelength diffraction grating is printed, after being light exposed by a specially designed radial phase mask that projects solely the ±1 diffractive orders transversally to the central tube axis. A first demonstration of the excitation of the mode in the microstructure is achieved by the holistic phenomenon and through a centred reflective conical mirror able to transpose plane to cylindrical waves and conversely. A fine spectral resonance in reflection in the near-infrared range is measured and subsequently analyzed by optical spectroscopic means. The design, fabrication, characterization of this structure are described as well as the first results of experimental resonant TE/TM reflection pick spectrum.

Paper Nr: 52
Title:

Achromatic Cascade Optical System with Hybrid Lenses for Distortion-compensated Multifocusing of Ultrashort Pulse Beams

Authors:

Jun Amako and Hidetoshi Nakano

Abstract: We report an achromatic cascade optical system for multifocusing ultrashort pulse beams in its application in high-precision materials processing. The challenge is to eliminate the beam-radius-dependent pulse broadening or pulse front distortion from the arrayed pulses. We propose the inclusion of a pair of hybrid refractive-diffractive lenses for chromatic aberration correction and dispersion management in the system. From numerical analysis, we have realized that the hybridized system has enormous potential to improve not only the spatial resolution but also the temporal resolution to their respective limits in generating arrayed pulse beams. This pulse delivery system enables high-throughput material processing using ultrashort-pulsed lasers.

Paper Nr: 54
Title:

Introducing Advanced Freeform Optic Design to Li-Fi Technology

Authors:

René Kirrbach, Benjamin Jakob and Alexander Noack

Abstract: The paper considers the potential of freeform optics for Li-Fi technology and presents design approaches for transmitter and receiver optics using ray mapping methodology and freeform Fresnel lens, respectively. Simulation results are then presented for models validation.

Paper Nr: 56
Title:

Elasticity and Depth Measurement using Both Secondary Speckle and Time Multiplexing Interference

Authors:

Ariel Schwarz, Nisan Ozana, Amir Semer, Ran Califa, Hadar Genish and Zeev Zalevsky

Abstract: In this paper, we describe a technique for elasticity and depth measurement via both secondary speckle and time multiplexing interference approach. Using external stimulation of elastic medium (in example: human tissue) by infra-sonic vibration, photons from different depths of the elastic medium were separated. In addition, this work uses a modulated laser that incorporates at the same scanning time, a speckle pattern tracking method for sensing surface tilting and interferometer method for sensing z-axis movements. In this paper, we present preliminary experiments showing the ability to separate data of light coming from different layers in the elastic medium.

Paper Nr: 63
Title:

Random Lasing Control with Optical Spatial Solitons in Nematic Liquid Crystals

Authors:

Armando Piccardi, Sreekanth Perumbilavil, Martti Kauranen, Giuseppe Strangi and Gaetano Assanto

Abstract: We discuss the synergy of reorientational self-focusing and random lasing in a dye-doped nematic liquid crystalline material. The laser emission resulting from amplification and multiple scattering inside the medium can be either modulated or triggered depending on the energy of the visible pump beam and the power of the near-infrared spatial soliton, respectively exciting the two nonlinear responses. Moreover, the presence of the self-induced waveguide improves the properties of the emitted beam, i. e., directionality and profile. Finally, the laser light can be re-directed by steering the spatial soliton with the aid of an external low-frequency electric field.

Paper Nr: 66
Title:

Thermal Analysis for Quantum Cascade Lasers using Experiments, Simulations and Structure Function Obtained by Static Measurement

Authors:

Shigeyuki Takagi, Hirotaka Tanimura, Tsutomu Kakuno, Rei Hashimoto and Shinji Saito

Abstract: In order to increase the output of quantum cascade lasers (QCLs), it is important to improve the heat dissipation. For investigating the relationship between the device structure and heat dissipation properties, three kinds of different QCL devices were prepared as follows. One is a device which has the ridge covered with SiO2 and thin Au, another is a device which has the ridge covered with SiO2 embedded with Au, and the other is a device which has the ridge covered with SiO2 embedded with Cu. The temperature distributions was measured with a thermos-viewer. In addition, relationship between structure and heat dissipation properties in these structure devices are analysed with a three-dimensional model. As a result, it was clarified from experiments and simulations to improve heat dissipation properties by embedding ridge with Au or Cu. Furthermore, the thermal properties of the QCL device was measured by the statics method to separate the thermal resistance of the ridge, that of substrate, and that of mount parts. It was shown that the thermal resistance improves by more than 2 K/W from 9.3 K/W to 6.9 K/W by embedding ridge with Au or Cu.

Paper Nr: 74
Title:

Analysis of Wavelength Effect on Birefringence Creation on PAH/PAZO Layer-by-Layer Films

Authors:

Maria Raposo, Ana M. Timóteo and Paulo A. Ribeiro

Abstract: The influence of wavelength of writing laser beam in the photoinduced birefringence dynamics on layer-by-layer (LBL) films of poly(allylamine hydrochloride) (PAH) and poly{1-(4-(3-carboxy-4-hydroxyphenylazo) benzenesulfonamido)-1,2-ethanediyl, sodium salt} (PAZO) was investigated. Results revealed that the increase of laser wavelength lead to a slower birefringence build up process, whereas the relaxation process stands approximately unchanged. The buildup celerity was shown to follow the film absorbance with wavelength. The imposition of excess energy density to the PAH/PAZO LBL film was also shown to induce morphological changes in the film surface,which are also wavelength dependent.

Paper Nr: 11
Title:

Fabrication of Aberration-corrected Diffraction Grating for Soft X-ray Grating Monochromator

Authors:

Yilei H. Li and Changqing Xie

Abstract: In this work, we present the design and fabrication of an aberration corrected diffraction grating for soft X-ray monochromator. Spherical mirrors, which induce spherical, coma and astigmatic aberration, degrade the performance of a grating monochromator. These aberrations are often corrected by aspherical mirrors. however, aspherical mirrors with high surface accuracy are very difficult to fabricate. We proposed a new diffraction grating, by carefully adjust the positions of grating lines, the wavefront of the diffracted light can be modified and the aberrations can be corrected under certain conditions and the performance of the monochromator can be improved. The aberrations of a typical Czerny-Turner monochromator are discussed in detail and the grating design method is proposed in this work. A lamina type aberration corrected reflective grating for soft X-ray is fabricated using e-beam lithography, and the detailed process is elaborated.

Paper Nr: 18
Title:

Research on Multi-wavelength and Multi-beam Illumination for Improving Object Illumination Uniformity

Authors:

Sun Quan, Ing Yu, Yang Yi, Yan Baozhu and Du Shaojun

Abstract: The imaging and tracking to the far dim objects in the air are usually difficult for detecting system to get their clear images and accurate positions, due to the objects neither emitting light nor reflecting sunlight. Using active laser illumination technology, the target will be illuminated and the echo intensity of target can be increased. The laser intensity spatial distribution on the target plane fluctuates usually remarkably due to the atmospheric turbulence and other causes, which will decrease image resolution and tracking accuracy in optical system. In this paper, we presented a method of using illumination with the supercontinuum spectrum laser beam combination to improve the effect of target illumination uniformity. As the atmosphere transmittance ratios differs with wavelength, we set up a multi-wavelength and multi-beam target illumination simulation system to represent the supercontinuum spectrum laser illumination effect. As the previous simulation results and the experimental results, which both reflect an improving effect of illumination uniformity significantly by increasing of the beam number. The illumination uniformity of single beam with multi-wavelength spectrum components was analyzed, and the simulation results of one single beam, three beams and six beams with 9 wavelength spectrum were compared, which showed that the illumination uniformity in target plane was improved with both the number of wavelength spectrum components and the number of beams increasing. It showed that multi-spectral multi-beam illumination had great advantages in improving illumination uniformity and the supercontinuum laser can be a good active illumination source.

Paper Nr: 22
Title:

Two-dimensional Laser Scanner with Low Mechanical Cross Coupling based on Piezoelectric Actuators

Authors:

Chen Wei, Luo Dong, Liang Yuanbo, Liu Peng, Chen Liangpei and Zhang Yizhou

Abstract: Traditional two-dimensional laser scanners usually employ two-degree-of-freedom flexible hinges. However, these flexible hinges suffer from mechanical cross coupling between axes, which will reduce the scanning accuracy and stability. To overcome the above disadvantages, a compact novel laser scanner based on piezoelectric actuators is presented. The scanner uses only three one-dimensional flexible hinges to achieve two-axis feature. The mechanical structure and principle are detailed. Then the capabilities of the scanner are tested by a performance test system. The test results show that the scanner has a tilt angle of 43.19 mrad for X-axis with resonance frequency at 149.21 Hz and 2.41 mrad for Y-axis with resonance frequency at 232.59 Hz. Its scanning nonlinearity is reduced from 3% to 0.5% for X-axis and from 6% to 1% after compensation. The test results and the actual scanning images prove the low mechanical cross coupling.

Paper Nr: 26
Title:

Band-limited Orthogonal Functional Systems for Optical Fresnel Transform

Authors:

Tomohiro Aoyagi, Kouichi Ohtsubo and Nobuo Aoyagi

Abstract: The fundamental formula in an optical system is Rayleigh diffraction integral. In practice, we deal with Fresnel diffraction integral as approximate diffraction formula. By optical instruments, an optical wave is subject to a band limited. To reveal the band-limited effect in Fresnel transform plane, we seek the function that its total power in finite Fresnel transform plane is maximized, on condition that an input signal is zero outside the bounded region. This problem is a variational one with an accessory condition. This leads to the eigenvalue problems of Fredholm integral equation of the first kind. The kernel of the integral equation is Hermitian conjugate and positive definite. Therefore, eigenvalues are real non-negative numbers. Moreover, we also prove that the eigenfunctions corresponding to distinct eigenvalues have dual orthogonal property. By discretizing the kernel and integral calculus range, the eigenvalue problems of the integral equation depend on a one of the Hermitian matrix in finite dimensional vector space. We use the Jacobi method to compute all eigenvalues and eigenvectors of the matrix. We consider the application of the eigenvectors to the problem of approximating a function and showed the validity of the eigenvectors in computer simulation.

Paper Nr: 31
Title:

Advances in Phase Retrieval by Transport of Intensity Equation

Authors:

Dingfu Chen, Anand Asundi, Liansheng Sui, Chongtian Huang, Chi Wang and Yingjie Yu

Abstract: There are many factors in the calculations of Transport of Intensity Equation, which may lead to the uncertainty of the retrieved phase. In this paper, effect of these parameters such as defocus distance, focus plane and magnification, on the results is studied. It is hoped that this would provide a more robust and reliable method for phase and optical height measurement. Furthermore, the effect of intensity derivatives calculated using two defocussed images as opposed to multiple images is also considered. A microlens array is chosen as the test sample in a commercial transmissive Transport of Intensity Equation system. From this study, it is concluded that the biggest factor influencing the result is the magnification, which is seen to provided totally different phase value for the same shape. Incorrect defocus distance or in-focus plane also lead to inaccurate reconstruction results while higher order differential provides better and more stable results than traditional two image differential.

Paper Nr: 42
Title:

Construction and Characterization of a Pump Source for a Microchip Laser for Space Applications

Authors:

Bruno Couto, Paulo Gordo and António Amorim

Abstract: In the context of an apparent increasing interest in remote exploration of rocky celestial bodies, a pulsed microchip laser for time-of-flight range finding applications is under development. This paper addresses the design construction and testing of the pump source for this laser unit. Considering the small mass, miniature size and high pump power the space application requires, open emitter semiconductor lasers become the only real option as a main pumping source. However, this type of geometry is limited by a beam profile with significantly different divergence values on the fast and slow axes. We endeavoured to correct this issue by collimating each of the axis independently. After a design and simulation stage, the lenses were mounted in front of the main pump source with the aid of a custom made wavefront sensor.

Paper Nr: 45
Title:

Empirical Study of Helical Bend Loss in Optical Fibers

Authors:

Ashitosh Velamuri, Ishan Sharma, Shakti Gupta and Pradeep K. Krishnamurthy

Abstract: We propose a method to estimate helical bend loss in optical fibers and extend the method to predict the loss in a different fiber. In our approach, we consider the in-plane bend loss as the reference and approximate the loss curve as an exponential function decaying with bend diameter. For in-plane bends, we compute loss over the bend diameter range of 9.5−19.5 mm at 1550 nm wavelength. For helical bends, we perform experiments for the same range of bend diameters and pitch values of 2,4,5,7 and 10 mm. We extend the exponential function approximation to the experimental measurements of helically wound fibers and obtain an empirical formula to estimate the helical bend loss. We find that for a given bend diameter, the bend loss increases initially with the pitch, attains a maximum value and then decreases below the corresponding in-plane bend loss. We extend the empirical formula developed for a single fiber with a specific refractive index to evaluate the helical bend loss in another fiber. We conduct the in-plane bend loss experiments for the new fiber and repeat the exponential fit and obtain fit coefficients. We calculate the fit coefficients for different pitch values using empirical formula and predict the helical bend loss. We compare the predicted loss with corresponding experimental measurements, which are in good agreement.

Paper Nr: 65
Title:

Occlusion-capable Head-mounted Display

Authors:

Kwangsoo Kim, Daerak Heo and Joonku Hahn

Abstract: Head-mounted display (HMD) is regarded as one of the most popular device for providing three-dimensional (3D) contents in virtual reality (VR) or augmented reality (AR). Technologies on HMD have been deeply studied because it has a potential to make the people enjoy 3D contents. In this paper, we propose the application for digital micro-mirror device (DMD) as both the filter and the combiner. DMD has a benefit that it generates many images in short time. The real background image and the image generated by the organic light-emitting diode (OLED) are watched through the DMD, and these two images are combined as one image to generate AR.

Paper Nr: 72
Title:

Implementation of a Visible Light Communication Link: Li-Fi with Smartphone Detection

Authors:

David Andrade, João P. Gomes and Paulo S. André

Abstract: The average bandwidth per user increases daily, being necessary to present solutions that can satisfy this growth. One possible solution is to explore the light emitting diodes (LED) features. Visible Light Communications (VLC) is an emerging technology that presents several advantages comparing to other alternatives that currently exist on the market. This solution can be use simultaneously for illumination and data transmission, being an economical alternative to wi-fi. In this work we proposed the use of a mobile phone camera combined with an application to attain a bitrate up to 1 kbit/s with BER lower that 10-3. The concept of colour shift multiplexing/modulation was explored showing the capacity to successfully increase the aggregate bitrate in a 3 time fold.

Area 3 - Photonics

Full Papers
Paper Nr: 5
Title:

Effect of Dispersive Reflectivity on the Stability of Gap Solitons in Dual-core Bragg Gratings with Cubic-quintic Nonlinearity

Authors:

Afroja Akter, Md. J. Islam and Javid Atai

Abstract: We consider dynamical stability of quiescent gap solitons in coupled Bragg gratings with dispersive reflectivity in a cubic-quintic nonlinear medium. It is found that there exist two disjoint families of quiescent solitons within the bandgap, namely Type 1 and Type 2 solitons. Also, in each family, there exist symmetric and asymmetric solitons. It is found that dispersive reflectivity has a stabilizing effect on asymmetric solitons. In addition, the symmetric Type 2 solitons are always unstable.

Paper Nr: 6
Title:

Bragg Grating Solitons in a Dual-core System with Separated Bragg Grating and Cubic-quintic Nonlinearity

Authors:

Nadia Anam, Tanvir Ahmed and Javid Atai

Abstract: We analyze the stability of solitons in a semilinear dual-core system where one core is linear with a Bragg grating and the other core is uniform and has cubic-quintic nonlinearity. It is found that there exist three spectral gaps in the model’s linear spectrum. The quiescent soliton solutions are found by means of numerical techniques. It is found that the soliton solutions exist only in both the upper and lower bandgaps. Two distinct and disjoint families of solitons (i.e. Type 1 and Type 2 solitons) are found in the upper and lower bandgaps that are separated by a border. Stability of solitons are analyzed numerically. The stability analysis shows that stable Type 1 solitons may only exist in a part of the upper bandgap. Type 2 solitons in both upper and lower gaps are found to be unstable.

Paper Nr: 20
Title:

Acousto-optic Time-Domain Optical Demultiplexer

Authors:

S. N. Mantsevich and V. I. Balakshy

Abstract: The design of acousto-optic (AO) time-domain demultiplexer is proposed. The characteristics of such AO device are examined experimentally. This demultiplexer combines the collinear AO tunable filter used for the optical spectrum components selection with the optoelectronic feedback circuit and self-oscillations frequency locking effect. The presented demultiplexer obtain the following characteristics: wavelength spacing between channels may be less than 1 nm, the channel passband width is 0.4 nm, the crosstalk attenuation between adjacent channels exceeds 42dB, the insertion loss is less than 2 dB.

Paper Nr: 30
Title:

Amplitude Vibration Measurement by Harmonic Frequency Analysis of a Distributed Acoustic Sensor

Authors:

Javier Preciado, David Sanahuja, Carlos Heras, Jesús Subías, Lucía Hidalgo, Iñigo Salinas, Pascual Sevillano, Juan J. Martínez and Asier Villafranca

Abstract: Distributed acoustic sensors (DAS) based in coherent optical time-domain reflectometry (C-OTDR) provide a cost-effective solution for intrusion monitoring of large civil infrastructures like pipelines, railways or motorways. Although detection of events is well demonstrated, an estimation of the amplitude of these events is difficult to achieve. We propose a new method to recover the amplitude of the vibration from the conventional C-OTDR backscattered power traces. It is based on the FFT analysis of the DAS signals. Using a discrete accelerometer as a reference, we have calibrated the response of an optical fiber DAS using known stimuli. A correlation between the amplitude of the vibration and the ratios of the amplitudes of harmonics to the fundamental of the DAS signals is demonstrated. This analysis overcomes the main issues of the amplitude measurement, related to the interaction between the stimulus and the interference pattern.

Paper Nr: 50
Title:

Fabrication and Characterization of Lead Sulphide Colloidal Quantum Dot Photodetectors for the Near Infrared

Authors:

L. Colace, A. De Iacovo, C. Venettacci and S. Bruno

Abstract: Colloidal quantum dots are attracting a lot of interest for the fabrication of optoelectronics devices. In particular, they are suitable for simple, low cost and efficient photodetectors. Here we report on our recent results on lead sulphide colloidal quantum dot photoconductors operating in the near infrared spectral range. We describe the device fabrication process and provide an exhaustive electrical and optical characterization. The photodetectors exhibit a responsivity as high as 46 A/W and specific detectivity of about 1.7·1011 cmHz1/2W-1. Performance are investigated as a function of the voltage bias, device geometry and optical power. An evaluation of the device stability over time was also carried out.

Short Papers
Paper Nr: 43
Title:

Influence of Processes of Photobleaching on Spectral Characteristics of Organic Nonlinear Optical Co-crystal 26DAP4N

Authors:

K. E. Zhevaikin, I. Y. Denisyuk, M. I. Fokina and V. E. Sitnikova

Abstract: In this paper, we used organic nonlinear optical materials based on 4-nitrophenol and 2,6-diaminopyridine co-crystals. The goal was to study the influence of photobleaching processes on spectral characteristics of mentioned co-crystals. We presented spectral characteristics of transmittance coefficients of material before photobleaching and after its exposure to light for 4 weeks. We also noted the breakdown of hydrogen bonds in a molecular complex of co-crystal under the influence of photobleaching. However, this breakdown does not lead to disruption of the integrity of the molecules that are a part of an aminopyridine-nitrophenol.

Paper Nr: 51
Title:

Lead Sulphide Colloidal Quantum Dots for Sensing Applications

Authors:

A. De Iacovo, C. Venettacci, S. A. Bruno and L. Colace

Abstract: Colloidal Quantum Dots (CQD) have been widely studied for their peculiar optical characteristics such as enhanced optical absorption and tunable absorption spectrum. Many different photodetectors have been proposed but overall performance is still poor from the point of view of the bandwidth and noise performance. Here we propose the employment of a PbS QD photoconductor as an ultra-high sensitivity fire detector, exploiting the outstanding device responsivity at low optical powers. Moreover, we demonstrate the outstanding flexibility of CQD based devices, employing our detectors also as simple pollution gas sensors for NO2 detection.

Paper Nr: 62
Title:

A Sensor for the Optical Detection of Dangerous Road Condition

Authors:

Armando Piccardi and Lorenzo Colace

Abstract: We present the design, realization and characterization of a sensor for the optical detection of hazardous road condition. The device exploits the radiation from a incoherent source to detect the polarized components of the light scattering from a rough surface and calculate a signal dependent on the surface state. We propose two distinct geometries, working with forward and backward scattering components, assessing the device performance in terms of reliability and compactness. In both cases, the sensor allows to discriminate potentially dangerous states like the presence of water (either wet surface or covered by a layer) or ice on an asphalt sample, in opposition to the dry surface representing a safe condition.

Paper Nr: 73
Title:

Combined Video Analysis of ICG and 5-ALA Induced Protoporphyrin IX and Hemoglobin Oxygen Saturation in near Infrared

Authors:

T. A. Savelieva, D. M. Kustov, P. V. Grachev, V. I. Makarov, E. E. Osipova and V. B. Loschenov

Abstract: Due to the high recurrence rate after the glial brain tumor removal, methods of intraoperative navigation have a high relevance, providing the most complete removal of tumor tissues with maximum preservation of healthy ones. In this work a combined visualization method is proposed with an assessment of fluorescence and diffuse reflectance images. Fluorescence intensity of 5-ALA-induced protoporphyrin IX allows visualization of tumor cells, distribution of indocyanine green fluorescence helps to visualize the vascular system of the tumor, and parallel mapping of the degree of oxygenation demonstrate the hypoxic regions. The images were obtained in the near infrared range of the optical spectrum in order to maximize the optical probing depth in the window of biological transparency.

Paper Nr: 23
Title:

Residual Stress Analysis of Aluminum-doped Zinc Oxide Films under Laser-Induced Recovery Process

Authors:

Yu-Chen Hsieh, Ching-Ching Yang, Chih-Chung Yang, Yu-Hsuan Lin, Kuo-Cheng Huang and Wen-Tse Hsiao

Abstract: In this study, a low-temperature annealing technique using an ultraviolet laser was proposed for inducing the crystallization of transparent conductive aluminum-doped zinc oxide (AZO) films. The technique was used in conjunction with a galvanometer scanner to adjust the laser energy density and scanning speed, thereby inducing the amorphous crystallization of thin films. X-ray diffraction was used to analyze the structural properties of annealed thin films. Analysis with different galvanometer scanning speed during annealing and laser pulse repetition rates during annealing revealed that the two diffraction peaks (i.e., the (002) and (103) peaks) of the zinc oxide thin films became more noticeable as the laser pulse repetition rate increased. When the galvanometer scanning speed during annealing was set to 400 mm/s and 600 mm/s, the full width at half of the maximum (FWHM) of the AZO thin films decreased while the annealing frequency increased. By contrast, when the annealing speed was 800 mm/s, increasing the annealing frequency caused the FWHM to decrease and then increase. An analysis of the residual stress of the annealed thin film confirmed that when the annealing speed was reduced from 800 mm/s to 400 mm/s, increases in laser pulse repetition rate resulted in increased residual stress.

Paper Nr: 37
Title:

Modeling and Analysis of Double Layer Motheye Anti Reflective Coatings on Organic Light Emitting Diode

Authors:

Chaya B. M., Sharon P. C., Vinith G. P. and Narayan K.

Abstract: In this work modeling of double layer motheye anti-reflective coating (DLAR) on organic light emitting diode (OLED) is presented. Finite difference time domain method (FDTD) and Fresnel reflection theory is used to study the reflection and transmission of light of Organic Light Emitting Diode (OLED) using Anti-reflective coatings (ARC). The double layer motheye anti-reflective coatings are incorporated on the surface of glass substrate of an OLED. This is done to reduce the losses existing in OLEDs substrate-air interface. The refractive index (RI) of the top and bottom layer of ARC is engineered and the thickness of the top and bottom layer anti-reflective coatings is modelled using Fresnel’s reflection theory. The effect of double layer motheye ARC on OLED for enhanced far field intensity is analysed. It is found that the far field electric intensity of DLAR based OLED has a significant enhancement compared to OLED with Single layer Antireflective coatings on the glass substrate.

Paper Nr: 38
Title:

Long-Range (>100km) Distributed Vibration Sensor based on Φ-OTDR Technique with Spread Amplification and Detection of Probe Pulses

Authors:

David Sanahuja, Javier Preciado, Jesús Subías, Carlos Heras, Lucía Hidalgo, Iñigo Salinas, Pascual Sevillano, Juan J. Martínez and Asier Villafranca

Abstract: This paper presents a set of results to demonstrate a long-range (>100km) distributed vibration sensor (DAS) based on the Coherent Optical Time Domain Reflectometry (Φ-OTDR) technique using distributed amplification of the probe pulses and detection of the backscattered traces, which demonstrates great capability to achieve long-range distances with great sensitivity. In this case, optical amplifiers have been placed along the sensing optical fiber, each one followed by a detection stage. Results for some traces detected in each of the spans along the sensing fiber, and some measurements of stimuli produced by a vibration at the end of each of the sections of the sensing fiber, are showed here. This work, framed in the project SACOH (Long-range Distributed Vibration Sensing by Coherent Rayleigh Backscattering), has been carried out in collaboration between the University of Zaragoza and the company APL (Aragón Photonics Labs).

Paper Nr: 59
Title:

New Photonic Materials based on Ag Nanoparticles Modified with Stilbene Dyes and Its Peculiar Behavior Studied with SERS

Authors:

Alexey N. Smirnov, Olga V. Odintsova and Elena V. Solovyeva

Abstract: In the recent years, there has been a growing interest in development of smart photoactive materials with variable properties. This work presents the SERS study of behaviour of organometallic composites obtained by modification of Ag nanoparticles in hydrosols with several amino derivatives of stilbene. The feasibility of bifunctional stilbenes to be the molecular linkers of Ag nanoparticles is discussed. The hot spots activity of such modified Ag nanoparticles is considered. Two exciting but not fully understood finding were made: i) tertiary amines can be used as the effective molecular linkers; ii) the structure of central fragment between two benzyl rings has a strong influence on the modifier ability to incorporate the Ag nanoparticles into agglomerates with hot spots. The limitations consisting in the pH value and the presence of chloride ions are described for a potential application of the developed hot spots substrates.