# PHOTOPTICS 2017 Abstracts

## Area 1 - Lasers

Full Papers
Paper Nr: 48
Title:

### Generation of Femtosecond Pulses in 1 μm Spectral Range by Dispersion Managment with Asymptotically Single-mode Hybrid Fiber

Authors:

#### S. S. Aleshkina, M. V. Yashkov, A. K. Senatorov, L. D. Iskhakova, M. M. Bubnov, A. N. Guryanov and M. E. Likhachev

Abstract: A novel technique for suppression of unwanted modes in the hybrid fiber with anomalous dispersion near 1 µm has been proposed and realized. For this aim a special absorbing layer was placed to the position of the hybrid mode electric field minimum. As a result all other mode has excessive loss in the spectral region near 1.06 µm. On the contrary the optical loss of the hybrid mode almost does not change. Realized fiber was used for high quality pulse compression down to duration of 440 fs and energy of about of 20 pJ. Intra-cavity dispersion management has allowed us to realize a master-oscillator with output pulse energy up to 0.55 nJ and pulse duration below 700 fs.

Paper Nr: 63
Title:

### Wavelength Tunable Passively Q-Switched Alexandrite Laser with Direct Diode-Pumping at 635 nm

Authors:

#### Ufuk Parali, Gabrielle Thomas, Ara Minassian, Xin Sheng and Michael J. Damzen

Abstract: We report on a wavelength tunable passively Q-switched Alexandrite laser directly red-diode-pumped at 635 nm. Passive Q-switching was achieved with a semiconductor saturable absorber mirror (SESAM) and wavelength tuning with a birefringent tuner. The pulse repetiton rate was variable on the pump power and wavelength and a maximum 27 kHz rate was achieved in fundamental TEM00 mode. The maximum average output power obtained was 41 mW. The Q-switched wavelength tuning band was studied between 740 nm and 755 nm. To the best of our knowledge, this is the first time that tunable TEM00 passive Q-switched operation of a diode-pumped Alexandrite laser has been achieved. The results obtained in this study can be significantly further optimised for performance. A new cavity configuration for this optimisation is described. Future work is expected to lead to the development of higher power, more efficient tunable passive Q-switched (and potentially passive mode-locked) diode-pumped Alexandrite laser sources in the near-infrared band and also ultraviolet region through frequency conversion.

Short Papers
Paper Nr: 18
Title:

### Spontaneous Emission of a Dressed Atomic System in a Strong Light Field

Authors:

#### A. V. Bogatskaya and A. M. Popov

Abstract: New approach to the study of the spontaneous emission of an atomic system driven by a strong light field is developed. This approach is based on the accurate consideration of quantum system interaction with vacuum quantized field modes in the first order of perturbation theory, while the strong light field is considered classically. The proposed approach is applied to study the dynamics of field-driven atomic systems. Among them are Rabi oscillations in two-level system, resonant and nonresonant Raman and Rayleigh scattering, interference stabilization of Rydberg atoms. It is demonstrated that analyzing the spontaneous emission allows to study the specific features of quantum systems dressed by the field.

Paper Nr: 53
Title:

### Beam Combining of SOA-based Bidirectional Tunable Fiber Compound-ring Lasers with External Reflectors

Authors:

#### Muhammad A. Ummy, Simeon Bikorimana and Roger Dorsinville

Abstract: A simple, stable and inexpensive dual- output port widely tunable semiconductor optical amplifier-based fiber compound-ring laser structure is demonstrated. This unique nested ring cavity enables high optical power to split into different branches where amplification and wavelength selection are achieved by using low-power SOAs and a tunable filter. Furthermore, two Sagnac loop mirrors which are spliced at the two ends of the ring cavity not only serve as variable reflectors but also channel the optical energy back to the same port without using any high power combiner. More than 98% coherent beam combining efficiency of two parallel nested fiber ring resonators is achieved over the C-band tuning range of 30 nm. Optical signal to noise ratio (OSNR) of + 45 dB, and optical power fluctuation of less than ± 0.02 dB are measured over three hours at room temperature.

Posters
Paper Nr: 37
Title:

Authors:

#### James Beil, Rebecca Swertfeger, Stephen Misak, Zihe Gao, Kent D. Choquette and Paul O. Leisher

Abstract: The beam propagation factor, M2, exists as one of very few measures of a laser’s performance, when really a more detailed analysis of the application and laser are necessary for judgement in most cases. In free-space optical communications, a crucial figure of merit is the proportion of diffraction-limited power in the farfield. A calculated structure has been made with a higher proportion of diffraction-limited power in the farfield than another calculated structure with a much better M2. This calculated structure has an M2 of 19, with 89% of its power within the diffraction limit in the far-field, compared to another calculated structure with M2 of 1.7 that has 86% of its power within the diffraction limit in the far-field.

Paper Nr: 59
Title:

### Investigating the Modal Dependencies of Beam Quality - Via Spectrally-resolved Imaging of the Mode Structure in Diode Lasers

Authors:

#### Stephen M. Misak, James A. Beil, Rebecca B. Swertfeger and Paul O. Leisher

Abstract: Laser beam quality is an important factor for free-space communication and other high power applications. To achieve the power requirements for such applications, there is a trade-off with the M2 Beam Quality factor. While direct diode lasers offer higher efficiency in a smaller footprint compared to solid-state and fiber laser systems, beam quality is poor due to multi-mode operation. M2 measurements compliant with ISO 11146 standards require numerous measurements, especially for multimode lasers. It is possible to use faster, modal decomposition methods for measuring M2 by employing a spectrometer to spatially separate the modes of a laser. This work presents a custom Echelle Grating Spectrometer for spatially separating laser modes. This tool provides the basis for an alternative method of M2 measurements via Modal Power Distribution analysis.

Paper Nr: 60
Title:

### Broadband Lasing Characteristics of a Chirped InAs/InP Quantum-Dash Laser

Authors:

#### E. Alkhazraji, M. Talal Ali Khan and M. Z. M. Khan

Abstract: We investigate the temperature dependent spectral characteristics of an InAs multi-stacked quantum-dash-inwell laser. The multi-stack active medium optical transitions are dispersed by varying the thickness of AlGaInAs barrier layers. The analysis is carried out via a Fabry-Perot 700 μm long-cavity laser with a ridge width of 2 μm at different temperatures. A lasing bandwidth of >40 nm is observed at room temperature with total optical power of >150 mW. Moreover, broadening of lasing spectrum is observed with increasing the temperature, due possibly to a thermionic assisted emission and to optical pumping, enabling a full exploitation of the inhomogeneous optical transitions within the active region which indicates an increase in the available states in the active region. Therefore, proper optimization of the multi-stack active medium is required to fully utilize these optical transitions while maintaining high quantum efficiency, and proper bandgap engineering the device structure.

## Area 2 - Optics

Full Papers
Paper Nr: 10
Title:

### Fluorescence Enhancement of Europium Ions in a Scattering Matrix

Authors:

#### Mitsunori Saito and Takahiro Koketsu

Abstract: Microlasers are usually composed of organic dyes that emit fluorescence with a high efficiency. Those dyes, however, lose their fluorescence function in a short time because of optically- or thermally-induced bleaching. This degradation is particularly serious with microdevices, since a high-powered beam is focused into a small volume of the device. The problem of the device degradation can be solved, if organic dyes are replaced by fluorescent lanthanide ions (europium, erbium, neodymium, etc.) that have a superior durability against optical and thermal hazards. The lanthanide ions, however, have a smaller absorption cross-section than organic dyes, and hence, a pump light for exciting the ions is absorbed insufficiently inside a microdevice. A long optical path is therefore required to enhance the excitation efficiency. Polyethylene glycol is a useful solvent for dispersing europium ions, since it turns to a translucent matrix by solidification. In this translucent matrix, pump light (396 nm wavelength) is scattered heavily, which leads to extension of the optical path and enhancement of the absorbance. Consequently, fluorescence of the europium ions (613 nm) becomes twofold stronger in the solid phase than the liquid phase.

Paper Nr: 11
Title:

### Reduction of Optical Rotation and Scattering in a Cholesteric Liquid Crystal Layer

Authors:

#### Mitsunori Saito and Junki Fujiwara

Abstract: Cholesteric liquid crystal usually exhibits an optical rotation owing to its chirality. In the infrared region, however, the optical rotation power disappears, since the light wavelength is too long to recognize the refractive-index change of the nanometer-sized chiral structure. Consequently, the cholesteric liquid crystal exhibits a polarization-independent refractive index in the long-wavelength infrared range. The effective refractive index takes a value between the ordinary and extraordinary indices regardless of the polarization direction. The refractive index decreases to the ordinary index, when a phase transition takes place by application of an electric voltage (the electro-optical effect). This polarizer-free device operation, however, used to be limited to the wavelength range beyond 4 μm, since the optical rotation remained in the short wavelength range. In addition, a heavy scattering occurred during the phase transition process. In this study, experiments were conducted to examine how the chiral pitch and the thickness of the liquid crystal layer affected these optical characteristics. When a liquid crystal with a chiral pitch of 5 μm was enclosed in a cell with a 3 μm gap, both the rotation power and scattering loss were reduced successfully in a wide spectral range extending to 2 μm wavelength.

Paper Nr: 12
Title:

### Whispering Gallery Mode Emission of a Cylindrical Droplet Laser

Authors:

#### Mitsunori Saito and Takuya Hashimoto

Abstract: A cylindrical droplet laser was fabricated in a silicone rubber by using a polyethylene-glycol solution of rhodamine 6G. The silicone rubber provided a simple molding process for enclosing the droplet, since silicone oil solidified at room temperature by only adding a curing agent. Polyethylene glycol dissolved a large amount of dye molecules, yielding a fluorescent solution whose refractive index (1.46) was higher than that of the silicone rubber (1.40). Consequently, some fluorescence rays circulated in the cylindrical droplet owing to the total internal reflection on the side surface (the whispering gallery mode). Other fluorescence rays made round trips in the radial or axial directions of the cylindrical droplet (the radial and axial modes) being reflected at the side or bottom surfaces. When the droplet was excited by a green laser pulse (wavelength: 527 nm, pulse duration: 10 ns), these emission modes competed with one another to induce a stimulated emission. In a droplet with 2.0 mm diameter and 1.4 mm height, the whispering gallery mode conquered the other emission modes, exhibiting a non-linear peak growth and a peak-width narrowing when the excitation energy exceeded 20 μJ (the threshold energy of the stimulated emission).

Paper Nr: 13
Title:

### Mueller Matrix Polarimetry by Means of Azimuthally Polarized Beams and Adapted Commercial Polarimeter

Authors:

#### Juan Carlos Gonzalez de Sande, Gemma Piquero and Massimo Santarsiero

Abstract: A simple method for Mueller matrix polarimetry is proposed. The experimental set up is based on using an azimuthally polarized input beam, which presents all possible linearly polarized states across its transverse section, and an adapted commercial light polarimeter for analyzing the polarization state of the output beam. It will be shown that by measuring the Stokes parameters at only three different positions across the output beam section, the complete Mueller matrix of linear deterministic samples can be easily determined.

Paper Nr: 19
Title:

### The Quasi-Triangle Array of Rectangular Holes with the Completely Suppression of High Order Diffractions

Authors:

#### Lina Shi, Hailiang Li, Ziwei Liu, Tanchao Pu, Nan Gao and Changqing Xie

Abstract: We propose the quasi-triangle array of rectangular holes with the completely suppression of high order diffractions. The membrane with holes can be free-standing and scalable from X-rays to far infrared wavelengths. Both numerical and experimental results demonstrate the completely suppression of high order diffractions. The desired diffraction pattern only containing the 0th and +1st/-1st order diffractions results from the constructive interference of lights from different holes according to some statistical law distribution. The suppression effect depends on the number of holes. Our results should be of great interest in a wide spectrum unscrambling for any wavelength range.

Paper Nr: 23
Title:

### High Order Diffraction Suppression of the Membrane with Hexagonal Hole Array

Authors:

#### Ziwei Liu, Lina Shi, Tanchao Pu, Changqing Xie, Hailiang Li and Jiebin Niu

Abstract: We propose the array of hexagonal holes with the completely suppression of the 2nd, 3rd, and 4th order diffractions. The membrane with holes can be free-standing and scalable from X-rays to far infrared wavelengths. We numerically and experimentally demonstrate that the 2nd, 3rd and 4th order diffractions near the 1st order diffraction are completely suppressed. The hexagonal hole with some size results in a desired diffraction pattern. Our results should be of great interest in a wide spectrum unscrambling for any wavelength range.

Paper Nr: 29
Title:

### Extremely Nondegenerate Two-photon Processes in Semiconductors

Authors:

#### David J. Hagan, Himansu S. Pattanaik, Peng Zhao, Matthew Reichert and Eric W. Van Stryland

Abstract: Direct-gap semiconductors show enhanced two-photon absorption and nonlinear refraction for the extremely non-degenerate case, i.e. for two light waves of very different wavelength, as compared to the degenerate case. We have verified this through measurements of non-degenerate two-photon absorption and nonlinear refraction in several direct-gap semiconductors. We have demonstrated application towards mid-infrared detection and imaging, as well as 2-photon gain in the mid infrared. We also show how semiconductor quantum wells may be employed to engineer even larger enhancements of these effects.

Paper Nr: 64
Title:

### Far L-band Single Channel High Speed Downstream Transmission using Injection-locked Quantum-dash Laser for WDM-PON

Authors:

#### M. Talal A. Khan, E. Alkhazraji, A. Ragheb, H. Fathallah and M. Z. M. Khan

Abstract: We demonstrate an externally modulated single channel 64 Gbit/s DP-QPSK transmission based on injectionlocked Fabry-Pérot broadband quantum-dash laser at far L-band ~1621 nm wavelength. A receiver sensitivity of -16.7 dBm has been observed after 10 km SMF transmission, with power penalty of ~2 dB, under the FEC threshold. We also propose that these novel quantum-dash laser diode could be a route towards next generation 100Gbit-PONs as a unified upstream and downstream transmitters.

Paper Nr: 68
Title:

### High Brightness Multi-Mode Fiber Lasers - A Novel Sources for in-Band Cladding Pumping of Singlemode Fiber Lasers

Authors:

#### Leonid V. Kotov, Oleg I. Medvedkov, Mikhail M. Bubnov, Denis S. Lipatov, Alexei N. Guryanov and Mikhail E. Likhachev

Abstract: A novel design of multi-mode Er-doped fiber lasers operated in the spectral region of 1530-1600 nm have been proposed and realized. The lasers efficiency exceed 35-42% (depending on the wavelength), while maximum output power is limited on the level of 60 W only by pump power available in the experiment. The developed multi-mode laser can be used as an efficient high-power and high-brightness pump source for Erdoped (pump at 1530-1535 nm) and Tm-doped (pump at 1560-1600 nm) singlemode fiber lasers. Utilization of the same concept to the Yb-doped lasers could strongly accelerate output power growth of single-mode lasers in the 1 μm region as well.

Paper Nr: 76
Title:

### Direct Observation of the 2D Gain Profile in High Power Tapered Semiconductor Optical Amplifiers

Authors:

#### Rebecca B. Swertfeger, James A. Beil, Stephen M. Misak, Jeremy Thomas, Jenna Campbell, Daniel Renner, Milan Mashanovitch and Paul O. Leisher

Abstract: A novel experimental approach to permit direct observation of the 2D gain profile in high power tapered semiconductor optical amplifiers and integrated MOPA devices is reported. A two-dimensional simulation of the photon, carrier, and gain distributions inside the tapered amplifier demonstrate gain saturation effects that could be measured by directly viewing the spontaneous emission profile inside of the cavity. Tapered lasers with a built-in window on the back of the device are fabricated and a SWIR microscope camera is used to measure the spontaneous emission profile under operation at varying injection levels. The effect of gain saturation due to stimulated emission is clearly observed and in close agreement with the theoretical model.

Paper Nr: 93
Title:

### On the Luminescence of (Ba0.5Sr0.5)2SiO4:Eu3+ upon X-ray Exposure

Authors:

#### Max-Fabian Volhard and Thomas Jüstel

Abstract: Eu2+ doped ortho-silicates are widely applied as luminescent materials in phosphor converted light emitting diodes (pcLEDs) (Park et al. 2003; Jüstel et al. 2012), due to their high quantum yield, strong absorption, short decay time, and long-term stability upon blue light excitation. The optical properties of (Ba1-x/2Sr1-x/2)2SiO4:Eux upon x-ray radiation are, however, much less known and were thus analysed in this work. It turned out that the activator ions in Eu3+ activated ortho-silicates are reduced to Eu2+ upon excitation by high energy radiation (> 5.0 eV). This reduction process can be monitored by the fading of the red line emission of Eu3+ in the range between 590 and 710 nm, originating from the [Xe]4f6-[Xe]4f6 transitions of Eu3+. At the same time, a novel green broad emission band caused by the interconfigurational transition [Xe]4f7-[Xe]4f65d1 shows up (fig. 1). This spectral change is a function of the irradiation period and can be quantified by the colour point shift of the emitted spectrum as well (fig. 2).

Short Papers
Paper Nr: 25
Title:

### Endogenous Fluorescence Analysis under Deep UV Excitation to Discriminate Human Brain Tumor Tissue - Difference between Glioblastoma and Healthy Control Tissue

Authors:

#### F. Poulon, F. Jamme, A. Ibrahim, C. Métais, P. Varlet, M. Juchaux, B. Devaux, M. Refregiers and D. Abi Haidar

Abstract: In order to build a multimodal nonlinear endomicroscope to image brain border during operation, our group is building an optical database on brain biopsy tissues analysis collected with excitation panning from deep UV to near infrared. This paper focuses on the results from deep UV excitation of endogenous fluorescence from glioblastoma and control human brain samples. The samples were imaged and spectrally analysed. The excitation wavelengths were tuned from 275 nm to 340 nm. Two promising indicators to discriminate tumorous tissue from the control were found. A preliminary correspondence between fluorescence images and histological H&E staining open a huge door to confirm results with a medical expertise.

Paper Nr: 27
Title:

### Viewing Angle Enhanced Point Light Source Display using Additional Light Sources

Authors:

#### Nomin-Erdene Dalkhaa, Gerelmaa Byambatsogt, Densmaa Batbayar and Ganbat Baasantseren

Abstract: A Viewing angle (VA) of Point Light Source (PLS) display, which is one type of Integral Imaging (InIm) display, is low. We proposed to enhance a VA of PLS Display. The new method used nine additional light sources to increase the VA 2.83 times larger than a conventional method along horizontal and vertical directions. These additional light sources will increase the angle of the ray that gathered by the elemental lens. From the experimental results, the VA of the proposed method is 2.55 times larger than the conventional method.

Paper Nr: 32
Title:

### Development of Instant Measuring Model for Oxygen Permeability and Water Content of Hydrogel Contact Lens

Authors:

#### Chih-Wei Hung, Kuo-Cheng Huang, Hsin-Yi Tsai, Yu-Hsuan Lin and Patrick Joi-Tsang Shum

Abstract: The diffusion coefficient D, gas solubility k of material and the thickness of lens t were used to evaluate the oxygen permeability Dk/t of contact lenses (CLs). However, the nominal value Dk/t is usually not consistent with the actual oxygen permeability of wearing CL. As the oxygen travel through the hydrogel, it need to be carried by water molecules in the lens material; thus, the higher the water content (WC) of the material, the higher the Dk/t value. In order to obtain the WC and Dk/t of wearing CL, we create a testing platform to simulate the wearing status of CL. When the light traveled through the lens, we found that the attenuation in green light is smoother than other wavelengths. Moreover, the WC is higher, its dewatering rate at room temperature is lower, and the light attenuation is relatively smaller. Comparing with the other CL of similar WC, the Dk/t of CL is higher if it has higher dehydration. In the study, we evaluated the WC and Dk/t of hydrogel CL based on the light attenuation in eight minutes. The attenuation degree of light after traveling through the CL can be used to estimate the Dk/t of hydrogel CL.

Paper Nr: 42
Title:

### Suppression of Zeroth-Order Diffraction in Phase-Only Spatial Light Modulator via Destructive Interference with a Correction Beam

Authors:

#### Wynn Dunn Gil D. Improso, Giovanni A. Tapang and Caesar A. Saloma

Abstract: We suppress the unwanted zeroth order diffraction (ZOD) contributed by the dead areas of a spatial light modulator with a correction beam that is independently created from the desired target. We use the Gerchberg- Saxton algorithm to generate the phase of the correction beam profile that would match correctly with that of the ZOD. The correction beam intensity is regulated using a coefficient to match also with that of the ZOD. Numerical simulation reveals a ZOD suppression that is as high as -99% but only -32% has been achieved so far experimentally.

Paper Nr: 44
Title:

### Combined High-Resolution Imaging and Spectroscopy System - A Versatile and Multi-modal Metrology Platform

Authors:

#### Tobias Hegemann, Fabian Bürger and Josef Pauli

Abstract: Multi- and hyperspectral measurement methods are a versatile approach to analyzing and understanding material properties. Especially imaging techniques allow for a precise sensing of surface properties. This paper presents a novel and multi-purpose metrology platform for high-resolution spectral measurements. The system is able to acquire multispectral images with six different spectral channels as well as hyperspectral point measurements and images. This is realized with a combined measurement head that includes a gray value camera as well as two spectrometers ranging from 190nm to 1,700nm. A three axis Cartesian robot with nanometer-precision allows the analysis of large samples with a size up to 40  10  10 cm and a weight of up to 25kg. Approaches to automatically focus both the camera and the spectrometers are presented. The calibration process between the camera and the spectrometers, which is necessary to acquire the full spectral information corresponding to each pixel of the camera image, is described. Example images and measurements are discussed to show the potential of the metrology platform.

Paper Nr: 47
Title:

### Quantum-enhanced Metrology without Entanglement based on Optical Cavities with Feedback

Authors:

#### Lewis A. Clark, Adam Stokes, M. Mubashir Khan, Gangcheng Wang and Almut Beige

Abstract: There are a number of different strategies to measure the phase shift between two pathways of light more efficiently than suggested by the standard quantum limit. One way is to use highly entangled photons. Another way is to expose photons to a non-linear or interacting Hamiltonian. This paper emphasises that the conditional dynamics of open quantum systems provides an interesting additional tool for quantum-enhanced metrology. As a concrete example, we review a recent scheme which exploits the conditional dynamics of a laser-driven optical cavity with spontaneous photon emission inside a quantum feedback loop. Deducing information from second-order photon correlation measurements requires neither optical non-linearities nor entangled photons and should therefore be of immediate practical interest.

Paper Nr: 73
Title:

### Synchronization between Two Fixed Cavity Mode Locked Lasers

Authors:

#### Shree Krishnamoorthy, Satyajit Mayor and Anil Prabhakar

Abstract: An active mode locked fibre ring laser is designed as a slave laser, driven by a commercial Ti:Sapphire laser acting as a master. The master-slave synchronization was stabilized for frequency detuning, but the output pulse width of the slave laser was observed to increase. The increase in pulse width was asymmetric about the ring cavity resonance frequency, a consequence of an asymmetry in the detuning range of the higher order cavity modes. We find that the detuning range decreases as the square of the mode number, in agreement with theory.

Paper Nr: 86
Title:

### Optimization of Transfer Times in Pinned Photodiodes

Authors:

#### Lutz Girgenrath, Martin Hofmann, Ralf Kühnhold and Holger Vogt

Abstract: An implantation scheme which enhances the readout speed of a silicon pinned photodiode (PPD) with large pixel length is presented. The basic PPD structure was developed for Time-of-Flight (TOF) distance measurement applications by the Fraunhofer IMS in Duisburg, Germany, and was fabricated in a standard 0.35 μm CMOS process. The optimized design of this PPD introduces the possibility to improve the electron readout speed by changing the n-well configuration with a second well implantation. The local increase in doping concentration creates a designated electron path which utilizes the reset voltage of the readout node. This behaviour is shown by simulation and measurement results are presented.

Paper Nr: 89
Title:

### Frequency Stabilization of an Adaptive Self-phase-conjugated Passively Q-switched Laser using Volume Bragg Grating on the Photo-thermo-refractive Glass

Authors:

#### S. A. Ivanov, A. P. Pogoda, N. V. Nikonorov, A. V. Fedin and A. A. Sergeev

Abstract: In conclusion, we successfully demonstrated laser frequency stabilization of an adaptive self-phase-conjugated passively Q-switched laser by mean of the transmitting volume Bragg grating on the photo-thermo-refractive glass. Application of such grating inside the cavity provides desired pulse to pulse frequency stability and reduce bandwidth of the radiation from 18 to 4 pm with outstanding output parameters such as pulse energy of 100mJ, peak power of 10MWt and beam quality of M2=1.15. We assume that the key factor of wavelength stabilization in our case is angular selectivity of the grating. But this kind of selection operates only with feedback mirror. These results have shown that transmitting volume Bragg gratings on photo-thermo-refractive glass are great candidate for stabilization of pulsed laser systems.

Paper Nr: 92
Title:

### Terahertz Transmission Through Patterened Vanadium Oxide Thin Films on Dielectric Substrates

Authors:

#### M. Akkaya, Y. Demirhan, H. Yuce, G. Aygun, L. Ozyuzer, C. Sabah and H. Altan

Abstract: Patterned and unpatterned films of vanadium oxide grown on dielectric substrates such as fused silica and sapphire were grown and analyzed by varying the temperature using terahertz time domain spectroscopy. After investigating the critical transition temperature near 340K, a well-known cross-shaped pattern was studied to observe any resonances upon transmission. Due to the poor conductivity of the films the frequency selective nature of the structure was not observed, however an etalon effect could be seen in the sapphire substrate as opposed to the fused silica substrate above the critical temperature. Dependence of the refractive index difference between substrates upon transmission of the THz pulse is likely in explaining this observed difference.

Posters
Paper Nr: 20
Title:

### Attachable Micro-endoscopy System to Conventional Microscope for Live Mouse Organ Imaging using 4f Configuration

Authors:

#### Yoon Sung Bae, Jae Young Kim and Jun Ki Kim

Abstract: The Micro-endoscopic technology combined with optical imaging system is essential for minimally invasive optical diagnosis and treatment in small animal disease models. Thus, the high resolution optical probe is required to achieve high resolution imaging. However, the optical imaging system requires highly precise and advanced technologies which are the main reasons for increasing system cost. Advancements in micro-optics and fiber optics technology have paved way in supporting compatibility among optical components. By providing compatibility between endoscopic system and existing conventional imaging equipment such as macro- or micro-scope, we could achieve in not only carrying out the high quality micro-endoscopic image procedure, but also reducing prices of the imaging system. The proposed system could be widely useful in the field of further biological study of animal disease model.

Paper Nr: 21
Title:

### Wide Broadband ASE Source based on Thulium-doped Fibre for 2 μm Wavelength Region

Authors:

#### M. A. Khamis and K. Ennser

Abstract: This paper investigates the generation of the amplified spontaneous emission (ASE) from thulium-doped silica fibre pumped at 1570 nm. The developed model provides the ASE spectral power at short and long wavelength bands by using two different thulium doped fibre types with optimized fibre length. Shorter wavelengths in the emission band can be accessed with a short thulium fibre, whereas longer wavelengths can be obtained using a long thulium fibre. Our findings reveal that, in contrast to a 100 nm (1800nm-1900nm) and 70 nm (1900nm-1970nm) broadband source at short and long wavelength bands, a broader spectrum source can be achieved at about 170 nm (1800nm-1970nm) by a combined of the two ASE spectra via a wideband 50:50 coupler. As a result, the proposed ASE source configuration doubles the bandwidth of the conventional single fibre based light source.

Paper Nr: 31
Title:

### Laser Micro-Structuring on Glass Substrates with Compensation Function for Multi-wavelength Mixed Laser Diode Module

Authors:

#### Yi-Cheng Lin, Chih-Chung Yang, Kuo-Cheng Huang and Wen-Tse Hsiao

Abstract: A glass substrate has excellent optical transmittance for the visible spectrum (400–700 nm). This study used three type glass (D263TTM, EAGLE XG○,R, and BK7) for laser micro-structuring in the light compensation technique applied to a multi-wavelength mixed light module. An ultraviolet laser system combined with a high-speed galvanometric scanner was used to fabricate microstructures on the specimen surface. The light compensation chromaticity properties of the microstructures on glass substrates depended on the laser machining conditions. The characteristics of the machined glass were systematically analyzed using a spectrophotometer and charge-coupled device camera. The experimental results demonstrate that the microstructures affected chromaticity under different laser micro-structuring pitches.

Paper Nr: 34
Title:

### Precision Lighting of LED Array using an Individually Adjustable Color Temperature and Luminous Flux Technology

Authors:

#### Min-Wei Hung, Wen-Ning Chuang, Cheng-Ru Li, Kuo-Cheng Huang and Yu-Hsuan Lin

Abstract: This paper presents a novel white light LED array equipped with a 3-pulse-width-modulation (PWM) control module that could separately adjust either the color temperature or luminous flux without influence on the other. An optical measurement system was set up to provide the complete information of color temperature, illuminance and spectrum of the LED array for analysis. The radiometry quantity of spectral data was converted into photometry quantity. The average percent deviations of color temperatures with a fixed illuminance, and illuminances with a fixed color temperature were estimated, respectively. Comparing with the existing commercial products, the developed LED array has better adjustability, stability and precision. The proposed innovations represent a novel solution for white light LED lighting technology and related applications.

Paper Nr: 38
Title:

### Partially Coherent Linearly Polarized Sources with Inhomogeneous Azimuth

Authors:

#### Juan Carlos González de Sande, Rosario Martínez-Herrero, Gemma Piquero and David Maluenda

Abstract: A new model of physically realizable electromagnetic source is proposed. The source is partially coherent and non-uniformly totally polarized. The coherence and polarization characteristics of this new source are analyzed. The spatial coherence area of the source can be easily modified at will. The state of polarization is linear across the transverse plane of the source with an azimuth that varies from point to point in a different way depending on the selected values of the parameters that define the source.

Paper Nr: 69
Title:

### Spectral Selective High Emissivity Pattern for Applications in near Infrared

Authors:

#### Enrique Carretero, Rafael Alonso and Cristina Pelayo

Abstract: In this work, we develop some high emissivity patterns for the near infrared range, between 1200 and 2500nm. These patterns were made by means of the magnetron sputtering technique, and they achieve their functionality by using the optical interference phenomenon so that their superficial reflectance is diminished. This is how we manage to produce surfaces that have a very low reflectance and high spectral emissivity in the abovementioned range. Such patterns can be used for the calibration of temperaturemeasuring systems based on photodiodes detecting near infrared radiation.

Paper Nr: 71
Title:

### Compensation Filters for Visualization of White Leds through the Ceramic Glass in Induction Cooktops

Authors:

#### Enrique Carretero, Rafael Alonso and Cristina Pelayo

Abstract: White LEDs visualization in induction cooktops is hindered by the non-uniformity in wavelength of the transmission of the ceramic glass used as the cooking surface, as it modifies the chromaticity of the LEDs. In this work, a compensation filter is developed by thin-film interference filter deposition techniques, which has a transmission spectrum that allows for the preservation of the light source intrinsic chromaticity. This permits a perfect visualization of white LEDs across ceramic glasses.

Paper Nr: 80
Title:

### Design the Structure of Vertical Multilayer Hybrid Silicon Waveguide to Work in Anomalous Dispersion Region

Authors:

#### Zengzhi Huang, Shuai Yuan and Jinsong Xia

Abstract: In order to decrease the dispersion of the silicon vertical slot waveguide, we propose a vertical multilayer hybrid silicon waveguide. The optical mode distribution of the multilayer waveguide is simulated by a finite element method. By a proper design of the waveguide parameters, the dispersion of waveguide can in the range of ±300 ps/nm/km in 1510-1590 nm, with one zero-group-dispersion point in the C band. This waveguide can be an alternative in on-chip nonlinear application, such as all optical signal processing.

Paper Nr: 81
Title:

### UV Pulsed Laser Irradiation Effect on Spectral Properties of Borosilicate and Phosphate Glasses with CuCl Nanocrystals

Authors:

#### Anastasiia Babkina, Ksenya Trots, Elena Kolobkova and Nikolai Nikonorov

Abstract: The results of the study of the pulsed UV laser radiation effect on the spectral properties of the borosilicate and the phosphate glasses doped with the copper chloride nanocrystals with the mean size of 26-70 Å are discussed. The changes of the exciton absorption spectra of the CuCl nanocrystals with various mean sizes induced by different duration of the laser exposure are studied. The effect of the phosphate glass transmission reduction in the visible region upon pulsed UV laser irradiation is obtained for the first time. The nature of the transmission reduction is discussed. The assumption is made that the transmission reduction is carried out through the formation of the color centers consisted of the Cun (n>13) clusters which have the absorption bands in the visible region. In conclusion the presence of the irreversible photochromism in the phosphate glass is stated.

Paper Nr: 91
Title:

### Fluorine Phosphate Glasses Doped with Cadmium Sulfide and Selenide Quantum Dots with High Quantum Efficiency at Room-temperature

Authors:

#### E. V. Kolobkova, Zh. Lipatova, M. S. Kuznetsova and N. Nikonorov

Abstract: The results of the study of the luminescent properties of the CdS(Se) quantum dots (QDs) with the mean size of 2-4 nm synthesized in the fluorine phosphate glass are discussed. The changes of the photoluminescence absolute quantum yield (PL AQY) magnitude of the CdS(Se) QDs with various mean sizes induced by the heat treatment are studied. It was found that the PL AQY of the CdSe QDs increases monotonically to a maximum and then fells down. PL AQY magnitudes for glasses doped with CdS QDs demonstrate weak dependence on the size. It was found that CdS(Se) QDs represents a series of excellent emitters in the 600-750 nm spectral region. PL AQY in the glasses can reach 50-65%, which is equal to the value in the colloidal nanocrystals and higher than it was reported earlier for the silicate glasses. The glass matrix protects the QDs from external influence and their optical properties remain unchanged for a long time.

## Area 3 - Photonics

Full Papers
Paper Nr: 16
Title:

### Moving Bragg Grating Solitons in a Grating-assisted Coupler with Cubic-Quintic Nonlinearity

Authors:

#### Md. Jahirul Islam and Javid Atai

Abstract: We analyze the existence and stability of moving Bragg grating solitons in a semilinear coupled system where one core is equipped with a Bragg grating and has cubic-quintic nonlinearity and the other is linear. The system's linear spectrum contains three bandgaps, namely the upper, lower and central gaps. The bandgap edges shift with the soliton velocity ($s$) and group velocity mismatch term ($c$) for a given coupling coefficient ($\kappa$), and result in change in the spectral widths. Two families of moving Bragg grating solitons (referred to as Type 1 and Type 2) are found that fill the upper and lower gaps only. No moving solitons are found in the central gap. The border separating the two families depends on both $c$ and $s$, and is determined numerically. We carried out systematic numerical stability analysis of the moving solitons and identified non-trivial stability borders in their parametric plane. The analysis also reveals that vast areas of stable Type 1 solitons exist in the system's parametric plane and that all Type 2 solitons are unstable.

Paper Nr: 17
Title:

### Effect of Dispersive Reflectivity on the Dynamics of Interacting Solitons in Dual-Core Systems with Separated Bragg Grating and Nonlinearity

Authors:

#### Tanvir Ahmed and Javid Atai

Abstract: The interactions of in-phase and p-out-of-phase quiescent Bragg grating solitons in a dual-core system where one core has Kerr nonlinearity and other is linear and has a Bragg grating with dispersive reflectivity are systematically investigated. The effect of dispersive reflectivity on the outcomes of the interactions is analyzed. It is found that above a certain value of dispersive reflectivity solitons develop sidelobes. The presence of sidelobes has a significant effect on the outcomes of the interactions. In the absence of sidelobes, in-phase soliton-soliton interactions may result in several outcomes such as merger into a quiescent soliton, symmetric or asymmetric separation of solitons or destruction of both solitons. However, the interaction of solitons in the presence of sidelobes produces other outcomes such as repulsion of solitons or formaion of a temporary bound state followed by separation of two solitons. p-out-of-phase solitons generally repel each other. However, in the presence of sidelobes, interactions of p-out-of-phase solitons may lead to the formation of temporary bound state and subsequent generation of two separating solitons.

Paper Nr: 51
Title:

### Mature 25Gb/s Silicon Photonic Platform towards Multi-Layer Circuits for High Integration Level Aplications

Authors:

#### C. Kopp, B. Szelag, D. Fowler, C. Dupre, K. Hassan and C. Baudot

Abstract: Silicon photonics is definitely a key technology in next-generation communication systems from Long-Haul networks to short reach data interconnects. To address 25 Gb/s and above applications, we present our R&D platform that uses a CMOS foundry line. The fabrication process is following a modular integration scheme which leads to a flexible platform, allowing various device combinations. Moreover this platform is associated to a device library in a PDK which includes specific photonic features and which is compatible with commercial EDA tools. Based on the maturity of this platform to build high-speed optical transceivers, we present our strategy to anticipate the next integration disruptive level by implementing multi-layer photonic circuits. Such a technology represents a new paradigm for the design of very high integration circuits that we consider first for optical interposer, and finally for optical network on chip with the convergence of photonics and electronics.

Paper Nr: 65
Title:

### Low-loss 1310nm/1550nm Integrated Silicon Duplexer based on a Directional Coupler

Authors:

#### Daivid Fowler, Bertrand Szelag, Vincent Hugues, Christian Sillans, Stéphane Bernabe and Christophe Kopp

Abstract: We describe the design, fabrication and measurement of an integrated silicon photonics O-band/C-band duplexer. The duplexer is based on a directional coupler and is designed to be polarisation insensitive at 1550nm in order to be used in conjunction with a broadband integrated edge coupler. The measured insertion losses are <1.3dB with a -1dB bandwidth of ~80nm.

Paper Nr: 70
Title:

### Fabrication of Microfluidic Channels by Femtosecond Laser Micromachining and Application in Optofluidics

Authors:

#### João M. Maia, Vítor A. Amorim, D. Alexandre and P. V. S. Marques

Abstract: Micromachining with femtosecond laser can be exploited to fabricate optical components and microfluidic channels in fused silica, due to internal modification of the glass properties that is induced by the laser beam. In this paper, we refer to the formation of microfluidic channels, where an optimization of the fabrication procedure was conducted by examining etch rate and surface roughness as a function of the irradiation conditions. Microfluidic channels with high and uniform aspect ratio and with smooth sidewalls were obtained, and such structures were successfully integrated with optical components. The obtained results set the foundations towards the development of new optofluidic devices.

Short Papers
Paper Nr: 58
Title:

### Acousto-optic Spectrum Analyzer - The New Type of Optoelectronic Device

Authors:

#### Sergey Mantsevich, Vladimir Balakshy and Yury Kuznetsov

Abstract: The new optoelectronic system combining calcium molybdate collinear acousto-optic cell and positive electronic feedback is proposed and examined both experimentally and theoretically. The feedback signal is formed at the cell output due to the optical heterodyning effect with the use of an unconventional regime of collinear cell operation. It is shown that the feedback circuit parameters enable controlling spectral characteristics of the acousto-optic cell, resulting in enhancing the maximal spectral resolution and the accuracy of optical wavelength determination. This system may be treated as the optical radiation spectrum analyzer, as the spectrum of electric signal in the feedback circuit is related with the light spectrum on the system input.

Paper Nr: 72
Title:

### Dispersion-scan Measurements of the Multiplate Continuum Process

Authors:

#### Miguel Canhota, Rosa Weigand and Helder Crespo

Abstract: Multiplate continuum (MPC) is a recent supercontinuum generation technique for spectral broadening of ultrashort laser pulses. In this work, we report the first direct temporal characterization of ultrashort laser pulses generated by the MPC process, without any further pulse manipulation apart from dispersion compensation, using the dispersion scan technique.

Paper Nr: 75
Title:

### Integrated Optical Devices - Fabrication of Multimode Interference Devices in Fused Silica by Femtosecond Laser Direct Writing

Authors:

#### Vítor A. Amorim, João M. Maia, D. Alexandre and P. V. S. Marques

Abstract: 1xN (N=2, 3, 4) MMI power splitters were fabricated in a fused silica substrate by laser direct writing, using a focused 515 nm amplified femtosecond laser beam, and characterized at 1550 nm. To accomplish this, several low loss waveguides were fabricated side by side to form a multimode waveguide with the output in a polished facet of the substrate, while a single low loss waveguide was fabricated to inject light in the centre of the multimode waveguide. The performance of the fabricated devices was optimized by testing three different designs.

Paper Nr: 84
Title:

### Hybrid Numerical Simulation of Fluid Flow and Light Distribution in a Bubble Column Photobioreactor

Authors:

#### Christopher McHardy, Giovanni Luzi, Jose Rodriguez Agudo, Antonio Delgado and Cornelia Rauh

Abstract: Cultivation of phototrophic microorganisms occurs often in closed photobioreactors (PBR). Thereby, the distribution of light inside PBR is a key factor for phototrophic growth and reactor productivity. To predict local light intensities, it is often assumed that the absorption rate is constant in space, and scattering by microorganisms is negligible. The present contribution aims to present a hybrid model to simulate fluid flow characteristics and its impact on light fields in a bubble column PBR. First, numerical simulations of bubble column flow have been performed. Afterwards, the computed local air volume fractions have been used to obtain local radiation characteristics of the gassed suspension, and polychromatic light fields were computed and compared to the optically homogeneous case.

Paper Nr: 94
Title:

### Optics-inspired Computing

Authors:

Abstract: We show that dispersive propagation of light has properties that can be exploited for extracting features from the waveforms. This discovery is spearheading development of a new class of digital algorithms for feature extraction from digital images with unique and superior properties compared to conventional algorithms. In certain cases, these algorithms have the potential to be an energy efficient and scalable substitute to synthetically fashioned computational techniques in practice today.

Posters
Paper Nr: 24
Title:

### Highly Sensitive Pressure Measurement based on Multimode Fiber Tip Fabry-Perot Cavity

Authors:

#### Wei ping Chen and Dong ning Wang

Abstract: In this work, a highly sensitive pressure measurement device based on multimode fiber filled with ultraviolet adhesive is presented. The experimental results show that the device has a high gas pressure sensitivity of -40.94nm/MPa, a large temperature sensitivity of 213 pm/°C within the range from 55 to 85°C, and a relatively temperature cross-sensitivity is 5.2kPa/°C. The fiber device is miniature, robust and low cost, in a reflection mode of operation, and has high potential in monitoring environment of high pressure.

Paper Nr: 26
Title:

### CdSe/ZnS (Core/Shell) Quantum Dots Multi-wallled Carbon Nanotubes (MWCNTs) on a Stainless Steel as a Photoanode in Solar Cells

Authors:

#### Junthorn Udorn, Hayashi Sachio, Shengwen Hou, Chaoyang Li, Akimitsu Hatta and Hiroshi Furuta

Abstract: Multi-walled carbon nanotube (MWCNT) forests grown on a stainless steel substrate were used as a photoanode in CdSe/ZnS (core/shell) quantum dot (QD) sensitized solar cells (QDSSCs). QD-treated MWCNTs on the conductive metal stainless substrate showed a higher power conversion efficiency (PCE) of 0.014% than those grown on a doped silicon substrate with a PCE of 0.005% under AM 1.5 sunlight intensity (100 mW/cm2). This higher efficiency can be attributed to the lower sheet resistance of 0.0045 Ω/sq for the metal substrate than the value of 259 Ω/sq for doped silicon. Additionally, the relationship between the reflectance of as-grown CNT and PCE is also examined. QDSSC fabricated from CNT of lower reflectance of 1.9 % at a height of 25 μm showed a better efficiency because the lower reflectance indicates the scattering of light repeatedly into deeper CNT forest resulting in higher absorption which indicates a higher surface area of CNTs to adsorb much amount of QDs on CNT forests, resulting in the higher PCE.

Paper Nr: 36
Title:

### Transmission and Thermal Emission in the NO2 and CO Absorption Lines using Macroporous Silicon Photonic Crystals with 700 Nm Pitch

Authors:

#### D. Cardador, D. Segura, D. Vega and A. Rodríguez

Abstract: Macroporous silicon photonic crystals with a cavity in the middle of their structure have been studied in both, transmission and emission. The initial transmittance of the photonic crystals was increased form 4%-6% up to the value of 25%-30% by performing a rear attach of the samples of approximately 160 µm. The use of wafers with 700 nm of pitch allowed us to fabricate the optical response of the photonic crystals in the ranges of 6.4 µm and 4.6 µm, where different gases have their absorption frequency –such as NO2 or CO. The fabricated samples have been also heated in order to evaluate their viability to be used as selective emitters for gas sensing purposes. Results show a good agreement in the position of the respective peak compared to the transmission spectrum. However, further studies have to be done to place the base of the peak as close as possible to the 0% of emission in order to have a better selective emitter. This work is a starting point for gas detection devices using macroporous technology in the mid-infrared, which includes ammonia, formaldehyde, carbon monoxide or nitrous oxide, among others.

Paper Nr: 61
Title:

### Improved Light Extraction Efficiency of Organic Light Emitting Diode using Photonic Crystals

Authors:

#### Chaya B. M., Venkatesha M., Ananya N. and Narayan K.

Abstract: In this work modelling of two dimensional of a fluorescence based Organic Light Emitting Diode (OLED) using plastic as flexible substrate is presented. The Finite Difference Time Domain (FDTD) mathematical modelling has been used to analyse the light extraction efficiency from fluorescence based Organic Light Emitting Diode (OLED). The OLED structure has been simulated by using 2D Hexagonal photonic crystal lattice. The Finite Difference Time Domain (FDTD) method is used to model and simulate the OLED structure. An enhancement of Internal Quantum Efficiency (IQE) and Light Extraction Efficiency (LEE) has been achieved by inserting Photonic Crystal above the emissive layer. The improvement in the extraction efficiency of OLED structure is achieved by increasing the radiative decay rate and by optimizing the angular distribution of light through the substrate.

Paper Nr: 77
Title:

### Fast Polarization Switch for Polarization-based Quantum Communication

Authors:

#### Vinicius M. Lima, Gustavo C. Amaral, Felipe Calliari, Guilherme P. Temporão, Jean Pierre von der Weid, Joaquim D. Garcia and João Pedro Garcia

Abstract: We present a complete optoelectronic unit for polarization visualization, switching and control. The system is based on a Field Programmable Gate Array (FPGA) unit and comprises: an acquisition unit containing an analog polarimeter and digital-to-analog converters; an FPGA capable of implementing an optimal algorithm for three-stage arbitrary polarization tracking; and an electronic driver with analog-to-digital converters capable of interfacing with Lithium-Niobate-based Polarization Controllers. The results, determined via simulation of real-parameter devices, show that fast polarization switch is achievable.

Paper Nr: 87
Title:

### PMMA/MEH-PPV Photoluminescent Polymer Blend as a Long Time Exposure Blue-light Dosimeter

Authors:

#### José Roberto Tozoni, Alexandre Marletta, Adryelle do Nascimento Arantes and Luana Rodrigues de Oliveira

Abstract: In the present paper the photoemission intensity versus excitation exposure time of host/guest photoluminescent polymer blend has been investigated. The polymer blend was composed by poly(methyl methacrylate) (PMMA) as a host, and Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEHPPV) as a guest. The photoluminescent blend was characterized by optical absorbance and steady-state photoluminescence spectroscopy. The PMMA/MEH-PPV blend film presented high homogeneity and high photoemission intensity. Moreover, the PMMA/MEH-PPV blend film photodegradation in function of sample exposure time to the blue-light excitation curve presented long biexponential time decay. These results suggest that the PMMA/MEH-PPV blend film could be used as a long time exposure blue-light dosimeter.