# PHOTOPTICS 2016 Abstracts

## Area 1 - Photonics

Full Papers
Paper Nr: 2
Title:

### Waveguide Evanescent Field Microscopies for Application in Cell- and Bacteria- Biophysics

Authors:

#### Silvia Mittler

Abstract: Two evanescent field microscopy technologies based on glass slab waveguides with permanent coupling gratings are presented: waveguide evanescent field fluorescence microscopy (WEFF) and waveguide evanescent field scattering microscopy (WEFS). The technologies are briefly described: the experimental setup is based on a conventional inverted microscope. A comparison to TIR and TIRF microscopy is given. The advantages of the waveguide method are clearly addressed. Various examples from for WEFF and WEFS microscopy are given. For WEFF: static distance mapping with a multimode waveguide, dynamic solubilisation studies of cell plasma membranes and the kinetic response of osteoblasts to trypsin. For WEFS: bacteria sterilization as well as cell adhesion and granularity studies. The latest development is a mass producible all-polymer-waveguide-chip to bring the technology to the interested scientific community.

## Area 2 - Lasers

Full Papers
Paper Nr: 7
Title:

### Electron Beam Sustained Plasma as a Medium for Amplification of Electromagnetic Radiation in Subterahertz Frequency Band

Authors:

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

Abstract: It is demonstrated that low-temperature weakly-ionized nonequilibrium plasma created by a high-energy electron beam in gases (gas mixtures) with Ramsauer minimum in a transport cross section and effective attachment of slow electrons can be used as a medium for amplification and generation of electromagnetic radiation in subterahertz frequency band. Analysis of the electron energy distribution function (EEDF) in Xe – F2 mixture is performed. Energy interval with growing EEDF is found to exist in such a mixture. Such an interval provides the existence of population inversion of the electron spectrum in continuum and is responsible for positive value of a gain factor of microwave radiation. A gain factor depending on an amplified radiation frequency and plasma parameters is analysed.

Paper Nr: 8
Title:

### Interference Stabilization and Possibility of Amplification and Lasing in Plasma Channel Formed in Gas by Intense Femtosecond Laser Field

Authors:

#### A. V. Bogatskaya, E. A. Volkova and A. M. Popov

Abstract: The effect of interference stabilization of Rydberg atoms in high-intensity laser field is proposed to create the plasma channel with population inversion between set of Rydberg states and the ground state for conversion of the input laser energy into the VUV and XUV frequency band. Furthermore, there is a possibility to create a population inversion between high-lying Rydberg states which can be used for lasing and amplification in the IR, mid-IR and sub-terahertz frequency band.

## Area 3 - Optics

Full Papers
Paper Nr: 18
Title:

### Spectral and Lifetime Measurements of the Endogenous Fluorescence Variation of Freshly Resected Human Samples over Time - Measuring Endogenous Fluorescence Changes at Different Moment after Tumor or Epileptic Cortex Excision

Authors:

#### M. Zanello, A. Ibrahim, F. Poulon, P. Varlet, B. Devaux and D. Abi Haidar

Abstract: Analysis of human tissue endogenous fluorescence is becoming a new modality of medical imaging. Its capacities represent the missing link between macroscopic radiological tools such as MRI and CT-scan and the surgeon view during surgical procedures. However, numerous aspects of this signal are not well known. Time dependence is one of these aspects. The aim of this work is to investigate the autofluorescence changes with time. Five ex vivo human samples were studied. Spectral and lifetime measurements were acquired each hour. Fluorescence intensity decreased slightly with time. This decrease existed for healthy and tumoral samples and did not affect the differences between them: higher fluorescence intensity for control samples compared to tumor samples. Lifetime values showed a slight decrease too for both type of tissue. This work is the first report of fresh human brain samples multimodal autofluorescence analysis with time.

Paper Nr: 26
Title:

### Design and Fabrication of Optical Devices based on New Polyfunctional Photo-thermo-refractive Glasses

Authors:

#### Nikolay Nikonorov, Vladimir Aseev, Victor Dubrovin, Alexander Ignatiev, Sergey Ivanov, Yevgeny Sgibnev and Alexander Sidorov

Abstract: Novel optical elements and devices (holographic volume Bragg gratings, gradient optical elements, optical and plasmonic waveguides, hollow structures, thermo-and biosensors, phosphors for LEDs, down-converters for solar cells) have been designed and fabricated based on new polyfunctional photo-thermo-refractive glasses. Some technologies (photo-thermo-induced crystallization, holograms recording, laser treatment, ion exchange, chemical etching) have been used. Shown that photo-thermo-refractive glasses can be used as a basic optical material for many photonics applications with the characteristics comparable with other commercially available materials.

Paper Nr: 39
Title:

### Development of an Accurate Laser Power Testing Kit for Safety Assessment of Commercial Laser Pointers in Thailand

Authors:

#### Kanokwan Nontapot and Narat Rujirat

Abstract: Recent advances in laser technology have enabled low-cost, more powerful, and more visible wavelengths of laser pointers. Large numbers of these high power lasers have found their way into people’s lives and are being used by people who may be unaware of potential eye injury, resulting in increased reports of retinal injuries. Therefore, many countries have issued restrictions or regulations, on the power limit of laser pointers used for demonstration purposes. At present, there are none of these regulations on the sale and use of laser pointers in Thailand. In this research, an accurate, inexpensive, user friendly, laser pointer power testing kit will be built for the measurement of optical power emitted from handheld lasers. The setup consists of a thermopile power meter, optical bandpass filters, lens mounts, lens tube, and iris. Output power of about 20 laser pointers randomly purchased from various sources will be determined, including evaluation of measurement uncertainty. The safety level with respect to the limits imposed by the US Code of Federal regulations will be also discussed.

Paper Nr: 69
Title:

### Tolerance to in-Band Crosstalk of Virtual Carrier-assisted Direct Detection Multi-Band OFDM Systems

Authors:

#### Bruno R. Pinheiro, João L. Rebola and Adolfo V. T. Cartaxo

Abstract: The tolerance to in-band crosstalk of virtual carrier (VC)-assisted direct detection (DD) multi-band orthogonal frequency division multiplexing (MB-OFDM) system is assessed numerically through Monte-Carlo simulation and considering a single interferer. The influence of the virtual carrier-to-band power ratio (VBPR) and the virtual carrier-to-band gap (VBG) of the interferer on the in-band tolerance is also studied. We show that, for interferers with the same VBG as the selected signal, the increase of the VBPR of the interferer leads to lower optical signal-to-noise ratio (OSNR) penalties. The increase of the VBG of the interferer with central frequency different from the selected signal also leads to lower OSNR penalties. When the central frequencies of the interferer and selected bands are the same, the variation VBG of the interferer can lead to 11 dB less tolerance to in-band crosstalk of the VC-assisted DD OFDM system.

Paper Nr: 73
Title:

### An Intelligent Speckle Reduction Algorithm for Optical Coherence Tomography Images

Authors:

#### Saba Adabi, Silvia Conforto, Anne Clayton, Adrian G. Podoleanu, Ali Hojjat and Mohammad R. N. Avanaki

Abstract: Optical Coherence Tomography (OCT) offers three dimensional images of tissue microstructures. Although OCT imaging offers a promising high resolution method, due to the low coherent light source used in the configuration of OCT, OCT images suffers from an artefact called, speckle. Speckle deteriorates the image quality and effects image analysis algorithm such as segmentation and pattern recognition. We present a novel and intelligent speckle reduction algorithm to reduce speckle based on an ensemble framework of Multi-Layer Perceptron (MLP) neural networks. We tested the algorithm on images of retina obtained from a spectrometer-based Fourier-domain OCT system operating at 890 nm, and observed considerable improvement in the signal-to-noise ratio and contrast of the images.

## Area 4 - Photonics

Full Papers
Paper Nr: 77
Title:

### Design and Test of SiPM Structures in CMOS Technology

Authors:

#### N. D'Ascenzo, V. Saveliev and Q. Xie

Abstract: In this paper we report our results on the influence of STI guard ring structures on the design and performances of SiPM with n+p microcells. Two types of SiPM detection structures were designed and fabricated in standard CMOS technology production line. A key-point of our study is the mathematical modelling and simulation of the structure using the well-estabilished CMOS technology simulation frameworks and models. We analyse the electric field and ionization coefficients of the designed structures at breakdown voltage. In addition, experimental characterization of the fabricated SiPM including current characteristics, CV characteristics was measured and analysed in order to identify the best structure for a correct CMOS implementation of the SiPM with STI guard rings.

Short Papers
Paper Nr: 9
Title:

### Performance Analysis of 1310/1490 Nm Demultiplexer based on Multimode Interference Coupler for PON

Authors:

#### Devendra Chack, V. Kumar and Dev Prakash Singh

Abstract: The design and analysis of a 1310/1490-nm demultiplexer based on Multimode Interference (MMI) coupler for Passive Optical Networks (PON) has been studied in this paper. Numerical simulations with finite difference Beam Propagation Method (BPM) have been utilized to optimize the operation of the proposed demultiplexer. The device has been designed with optimized width and MMI length and its analysis has been done based on extinction ratio and Insertion loss. Restricted interference has been used to reduce the size of the device. The device has been solely designed using 1310 nm as upstream and 1490 nm as downstream of data for Passive Optical Network communication system.

Paper Nr: 12
Title:

### Dynamics of Interacting Bragg Grating Solitons in a Semilinear Dual-core System with Cubic-quintic Nonlinearity

Authors:

#### Md Jahirul Islam and Javid Atai

Abstract: The interaction dynamics of in-phase Bragg grating gap solitons in a semilinear dual-core optical waveguide, where one core has cubic-quintic nonlinearity and equipped with Bragg grating and the other is linear, are investigated. The model supports two disjoint families of Bragg grating solitons (referred as Type 1 and Type 2). It is found that the interactions of two stable in-phase ($\Delta\theta=0$) quiescent solitons result in several outcomes. The possible interaction outcomes between two solitons may include symmetric or asymmetric separation, merger into one quiescent or moving soliton, destruction of one or both solitons and the formation of three solitons. It is found that the outcomes of the interactions are dependent upon the strength of quintic nonlinearity ($q$), initial separation ($\Delta x$) of the solitons, coupling-coefficient ($\kappa$) between the cores and the group velocity term ($c$) in the linear core.

Paper Nr: 13
Title:

### Effect of Dispersive Reflectivity on the Stability of Gap Solitons in Systems with Separated Bragg Grating and Nonlinearity

Authors:

#### Tanvir Ahmed and Javid Atai

Abstract: The existence and stability of quiescent solitons in a dual core optical medium, where the one core has only Kerr nonlinearity while the other has Bragg grating and dispersive reflectivity are investigated. Three spectral gaps are identified in the systems linear spectrum, in which both lower and upper band gaps overlap with one branch of the continuous spectrum for all values of normalized group velocity $c$ in the linear core; and, the central band gap remains a genuine bandgap. Soliton solutions exist only in the lower and upper gaps. In the absence of dispersive reflectivity, stable solitons are only found in the upper bandgap. However, introduction of dispersive reflectivity significantly alters the stability characteristics of solitons and results in the stabilization of solitons in a portion of the lower bandgap.

## Area 5 - Optics

Short Papers
Paper Nr: 15
Title:

### Laser-based Soldering Technique for Hermetical Sealing of the Calibration Target for the Exomars’ Raman Instrument

Authors:

#### Thomas Burkhardt, Michael Seifert, Pol Ribes, Nicolas Lange, Guillermo Lopez-Reyes, Andoni Moral-Inza and Antonio Sansano

Abstract: We propose the laser-based Solderjet Bumping as a full inorganic joining technique for the hermetical sealing of a possible calibration target container for the ExoMars Raman Laser Spectrometer. This technique allows the adhesive free bonding in a flux free and localized soldering process. We show a finite elements analysis based optimization of a soldering adapted design for the calibration target container. Current experimental results document hermetical sealing of a stainless steel tube with BK7 and D263 windows with a helium leakage rate down to 5·10-6 mbar·l·s-1.

## Area 6 - Lasers

Short Papers
Paper Nr: 20
Title:

### Hi-Bi Sagnac Interferometer Application for Wavelenght Tuning in CW and Actively Q-switched Erbium Fiber Laser

Authors:

#### Manuel Durán-Sánchez, Ricardo I. Álvarez-Tamayo, Olivier Pottiez, Baldemar Ibarra-Escamilla, Evgeny A. Kuzin and Antonio Barcelata-Pinzón

Abstract: An experimental analysis for the use of a Sagnac interferometer with high birefringence fiber in the loop as generated laser wavelength tuning device in a ring cavity Erbium-doped fiber laser in continuous wave and pulsed actively Q-switched regimes is presented. The maximal tuning range of ~26.72 nm depends on the Sagnac interferometer wavelength spectrum period of ~30.32 nm. The wavelength tuning of the generated laser line is performed by wavelength displacement of Sagnac interferometer spectrum by temperature variations applied on the fiber loop. Experimental results of the laser spectrum in continuous wave and actively Q-switched operations, and Q-switched pulses characteristics are shown.

## Area 7 - Optics

Short Papers
Paper Nr: 32
Title:

### Optimizing Energy Absorption for Ultrashort Pulse Laser Ablation of Fused Silica

Authors:

#### Nicolas Sanner, Maxime Lebugle, Nadezda Varkentina, Marc Sentis and Olivier Utéza

Abstract: We investigate the ultrafast absorption of fused silica irradiated by a single 500 fs laser pulse in the context of micromachining applications. As the absorption of the laser energy is rapid (~fs), the optical properties of the material evolve during the laser pulse, thereby yielding a feedback on the dynamics of absorption and consequently on the amount of energy that is absorbed. Through complete investigation of energy absorption, by combining “pump depletion” and “pump-probe” experiments in a wide range of incident fluences above the ablation threshold, we demonstrate the existence of an optimal fluence range, enabling to turn transiently the material into a state such that each photon is optimally utilized for ablation.

Paper Nr: 35
Title:

### Proposed Resource Allocation Schemes for Rainy Free Space Optical Network

Authors:

#### Abdallah S. Ghazy, Hossam A. I. Selmy and Hossam M. H. Shalaby

Abstract: Free space optical (FSO) connections present promising solution for the limited access issue of the last mile networks. However, several factors contribute to significant FSO link performance degradation. One of Most serious conditions is the influence of the rain, that frequently appear, thus making the implementation of strongly connected FSO networks a demanding issue. Dynamic FSO networks is attractive ones over the robust static ones, i.e, partial and full relayed networks, for this demanding issue. In this paper two new resource allocation Schemes are proposed for cooperative-dynamic FSO networks, as attractive solution for both atmospheric variation and high cost of robust static network problems. Each Scheme is formulated as integer linear multi-objective optimization problem (ILP-MOP), where reliability-fairness, capacity and bit-error rate functions are targeted. And each scheme is composed of lexicographic, lex-max-min and lex-min-max criteria. Each ILP-MOP is solved using exhaustive search method to obtain the guaranteed optimal solution(s). The simulation results is used to reveal that two schemes are more reliable-fairness and cost efficient than the robust static topology, specially at sever weather conditions. Also, the results show the two schemes have different behavior, where one prioritize the reliability-fairness over capacity utilization and the another does the opposite.

## Area 8 - Photonics

Short Papers
Paper Nr: 37
Title:

### Phosphor in Glass based on High Refractive Index Glasses for LEDs

Authors:

#### Vladimir Aseev, Anastasiya Bibik, Yuliya Tuzova, Elena Kolobkova, Ksenia Moskaleva and Nikolay Nikonorov

Abstract: Composite “phosphor-in-glass” based on high refractive index lead-silicate glass and YAG:Ce and SiAlON powder has been developed and synthesized. Glass composition optimization in the order to reduce scattering at glass/phosphor interfaces has been performed. Samples of composite light-converting materials for white LEDs were prepared by sintering glass powders and phosphor at 600 °С. Spectral, luminescent and structural properties of the obtained composites have been investigated. White LEDs based on the composite glass phosphor materials obtained have been tested. The color temperature of the probe LED was found to be 4370 K with the luminous efficacy 58lm/W.

## Area 9 - Optics

Short Papers
Paper Nr: 40
Title:

### Light Amplification and Nonlinear Microscopy by Stimulated Raman Scattering

Authors:

#### M. A. Ferrara, A. D'Arco, M. Indolfi, N. Brancati, L. Zeni and L. Sirleto

Abstract: The Stimulated Raman Scattering has important connections with nanophotonics and biophotonics. Concerning nanophotonics, one of the most recent challenges is the investigation of ‘nonlinear optical phenomena at nanoscale’. Among them, stimulated Raman scattering is one of the most interesting, due to its significant implications from both fundamental and applicative point of view. In this paper, comparison among experimental investigations of stimulated Raman scattering in amorphous silicon nanoparticles and in silicon micro- and nano-crystals, at the wavelengths of interest for telecommunications, are reported. In addition, concerning biophotonics, first, the implementation of femtosecond Stimulated Raman Spectroscopy (f-SRS), as a single point of scanning microscopy, is described. Then, the integration of f-SRS in a laser scanning microscope and label free imaging of polystyrene-beads are demonstrated.

Paper Nr: 41
Title:

### Improving the Point Spread Function of an Aberrated 7-Mirror Segmented Reflecting Telescope using a Spatial Light Modulator

Authors:

#### Mary Angelie Alagao, Mary Ann Go, Maricor Soriano and Giovanni Tapang

Abstract: We reduce the aberrations in a segmented reflecting telescope composed of seven identical concave mirrors by correcting the point spread functions (PSFs) using a a spatial light modulator. We first calculate and compare the PSF of a segmented reflecting telescope and a monolithic reflecting telescope, both having the same aperture diameter. We simulate the aberrations using the Zernike polynomials and add these to the PSF of the segmented mirror. Using the Gerchberg-Saxton (GS) algorithm, we retrieve the phase information used to correct for these aberrations. Results show an improvement in the imaging resolution of the telescope due to the correction phase applied.

Paper Nr: 45
Title:

### Analysis of Multicore Fibre Transmission with Space Coding Scheme

Authors:

#### Makoto Tsubokawa

Abstract: We analysed the space coding scheme applied to the space division multiplexing transmission in two types of multicore fibres with different intercore crosstalk. Rather than the usual optical multiple-input and multiple-output processing, simple space coding based on optical code division multiplexing was used to achieve separate detection of the desired signals. The signal to interference-and-noise ratio has a positive value when the relative phase drift between the optical signals in different cores is suppressed to values typically less than ~p/10. Although a complete solution of the phase drift control problem was not achieved, this scheme suggests that real-time MCF transmissions are possible.

Paper Nr: 46
Title:

### On the Use of OCT to Examine the Varnish Layer of Paintings Cleaned with an Er:YAG Laser

Authors:

#### Adele DeCruz, Joseph A. Izatt and Derek Nankivil

Abstract: Optical Coherence Tomography (OCT) was used to visualize and quantify the varnish layer of paintings. And to verify the success of efforts by conservators to remove the varnish using laser ablation. An Er:YAG laser (λ = 2.94μm) with a repetition rate of 15Hz and an optical power of 1mW was used to remove the varnish. A spectral domain OCT system with a Michelson topology was constructed using a broadband super-luminescent diode (λ = 840±25nm). The OCT system provided an 8μm resolution, and a field of view of 5x5mm. Samples, including pigment, varnish and substrate, approximately 1mm2 in size, were removed from the oil painting, San Giorgio Maggiore by Martin Rico (1833-1908). Varnish thickness obtained from OCT was validated by similar measurements obtained from SEM analysis. Other paintings, including a late 18th century landscape, signed Thomas Gainsborough, were imaged with OCT to compare neighboring regions before and after laser treatment and to examine the layering of the artist’s signature in an effort to determine its authenticity. In conclusion, the non-invasive OCT technique is an efficient tool for measurement of varnish layer thickness, for imaging over-paint under varnish layers, and for assessing the effectiveness of laser assisted varnish removal.

Paper Nr: 50
Title:

### Low Order Aberrations Compensation by Direct Adjustment of the Reflective Beam Shaper in Slab Laser

Authors:

#### Liu Wenguang, Zhou Qiong, Wang Gang, Xie Kun, Yan Baozhu and Xi Fengjie

Abstract: A direct method for compensation of low order aberrations with large PV value was presented in this paper. In which, the relationship between the optical layout parameters and the output aberration coefficients were derived by ray matrix method. Then, the adjustment parameters calculated by the equations were used to change the optical layout parameters to compensate the low order aberrations with defocus and astigmatism. The effectiveness of this method was verified by simulations based on the optical models built in a optical design software. It shows that the low order aberrations can be accurately compensated to a level below 0.5λ by the direct method.

## Area 10 - Photonics

Short Papers
Paper Nr: 62
Title:

### Near-infrared Silicon Schottky Photodiodes based on Non-metallic Materials

Authors:

#### Maurizio Casalino, Mariano Gioffrè, Mario Iodice, Sandro Rao and Giuseppe Coppola

Abstract: In this work we have investigated the performance of Schottky photodetectors based on materials non-conventionally used to detect near-infrared wavelengths. In the proposed devices the absorption mechanism is based on the internal photoemission effect. Both three-dimensional (sputtered erbium and evaporated germanium) and two-dimensional materials (graphene) have been considered and their performance compared. Our insights show that silicon Schottky photodetectors have the potentialities to play a key role in the telecommunications opening new frontiers in the field of low-cost silicon photonics.

Paper Nr: 64
Title:

### Performance Analysis of Photonically Generated Microwave Signal using a Dual-parallel Dual-drive Mach-Zehnder Modulator in Dispersive Media

Authors:

#### Amitesh Kumar, Vishnu Priye and Kowshik Moyya

Abstract: Dispersion is one of the potential limiting parameter for generation of microwave signal using photonic methods. In this paper, we analyse theoretically, the influence of fiber dispersion parameter on the photonically generated microwave/millimeter wave signal using dual-parallel dual-drive LiNbO3 Mach- Zender modulators. Intensity at the output of photodetector having, eight and sixteen times frequency of microwave drive signal and harmonic suppression versus modulation index (ß) and filter attenuation is discussed and it has been found that dispersion plays a major role on generation and transmission of microwave signal in optical domain.

## Area 11 - Optics

Short Papers
Paper Nr: 66
Title:

### NUMERICAL ANALYSIS OF A NEW POLYMER PHOTONIC CRYSTAL FIBER FOR SENSING APPLICATIONS

Authors:

#### Issam Haddouche and Cherbi lynda

Abstract: In this paper a new sensor design based on the enhancement of the evanescent field of the propagating modes is presented, the sensor is a modified Photonic Crystal Fiber (PCF) with Teflon AF used as a background material. Assessment of the sensor's performance is made by calculating Confinement loss of the waveguide. Full-Vector Finite Element Method is used throughout the analysis. Results show a remarkable enhancement in the evanescent field for this sensor compared with standard PCF waveguide.

Paper Nr: 68
Title:

### Testing of Micro-optics using Digital Holographic Interferometric Microscopy

Authors:

#### Varun Kumar and Chandra Shakher

Abstract: Digital holographic interferometric microscopy (DHIM) is used as metrological tool for the testing of micro-optics. The paper presents the measurement of sag height (h), radius of curvature (ROC), and shape of micro-lens. The advantage of using the DHIM is that the distortions due to aberrations in the optical system are avoided by the interferometric comparison of reconstructed phase with and without the object.

Paper Nr: 70
Title:

### Light Properties Improvement of Light Emitting Woven Textiles with Optical Fibres for Photodynamic Therapy

Authors:

#### Yesim Oguz, Cedric Cochrane, Vladan Koncar and Serge Mordon

Abstract: For an efficient and less painful photodynamic therapy (PDT), a light emitting fabric (LEF) was woven from plastic optical fibres (POF) aiming at the treatment of dermatologic diseases such as Actinic Keratosis (AK). The traditional PDT treatments applied with external light sources deliver a non-uniform light distribution on the skin surface due to the anatomical particularity of the human body (head vertex, hand, etc.). Therefore a successful PDT obligates a homogenous and reproducible light delivery. With this purpose, plastic optical fibres (POF) have been woven in textile in order to create macro-bendings and thus emit out the injected light directly to the skin. To improve the light intensity and light emitting homogeneity of the LEF, Doehlert Experimental Design is applied. Fifteen experiments performed to analyze the response surface. Light properties of the prototypes were evaluated. The proposed models fitted well with the experimental data and enabled the optimal set up the warp yarns tensions. This study showed that RSM was a suitable tool to optimize the models of light diffusion properties.

Paper Nr: 71
Title:

### Investigation on Compressed Wavefront Sensing in Freeform Surface Measurements

Authors:

#### Eddy Chow Mun Tik, Xin Wang, Ningqun Guo, Ching SeongTan and Kuew Wai Chew

Abstract: In this paper, conventional modal wavefront reconstruction is compared with compressed wavefront sensing to reconstruct freeform surface profiles using the Shack-Hartmann wavefront sensor. The modal wavefront reconstruction represents the phase or the wavefront in the Zernike domain. The compressed wavefront sensing method based on the sparse Zernike representation (SPARZER) represents the phase slopes in the Zernike domain. The effectiveness of compressed wavefront sensing in freeform surface profile measurements is investigated.

Paper Nr: 72
Title:

### Enhancing the Performance of Random Lasers - Effects of Localised Surface Plasmons and Resonance Energy Transfer

Authors:

#### Judith M. Dawes, Wan Zakiah Wan Ismail, Ewa M. Goldys and David W. Coutts

Abstract: We investigate the effect of different gain media and different scattering media in random lasers. We demonstrate an increase in the emission intensity and efficiency of random lasing by incorporating gold rather than dielectric alumina nanoparticles. There is a trade-off between enhancing the random laser performance due to the localised surface plasmon resonance field effects and reduction in performance due to fluorescence quenching by the gold nanoparticles. We use fluorescence resonant energy transfer between dye molecules to extend the wavelength range of emission.

Paper Nr: 90
Title:

### Depth Resolution in Coherent Hemodynamics Spectroscopy

Authors:

#### Angelo Sassaroli, Xuan Zang, Kristen Tgavalekos and Sergio Fantini

Abstract: Coherent hemodynamics spectroscopy (CHS) is a novel method based on the frequency-resolved study of induced hemodynamic oscillations in living tissues. Approaches to induce hemodynamic oscillations in human subjects include paced breathing and cyclic thigh cuff inflation. Such induced hemodynamic oscillations result in coherent oscillations of oxy-, deoxy-, and total hemoglobin concentrations in tissue, which can be measured with near-infrared spectroscopy (NIRS). The novel aspect of CHS is to induce hemodynamic oscillations at multiple frequencies in order to obtain frequency-resolved spectra of coherent hemodynamics. A dedicated mathematical model recently developed by our group, can translate the phase and amplitude spectra of these hemodynamic oscillations into physiological parameters such as capillary and venous transit times, and the autoregulation cutoff frequency. A typical method used in near-infrared tissue spectroscopy to measure oscillations of hemoglobin concentrations is based on the modified Beer-Lambert law, which does not allow for the discrimination of hemodynamic oscillations occurring in the scalp from those occurring in the brain cortex. In this work, we show preliminary results obtained by using diffusion theory for a two-layered medium, so that the hemodynamic oscillations obtained for the first and second layer are assigned to hemodynamic oscillations occurring in the scalp/skull and brain cortex tissues, respectively.

## Area 12 - Lasers

Short Papers
Paper Nr: 93
Title:

### Watt-level Flat Supercontinuum Source Pumped by Noise-like Pulse from an All-fiber Oscillator

Authors:

#### He Chen, Shengping Chen, Zongfu Jiang and Jing Hou

Abstract: We demonstrate Watt-level flat visible supercontinuum (SC) generation in photonic crystal fibers, which is directly pumped by broadband noise-like pulses from an Yb-doped all-fiber oscillator. The novel SC generator is featured with elegant all-fiber-integrated architecture, high spectral flatness and high efficiency. Wide optical spectrum spanning from 500 nm to 2300 nm with 1.02 W optical power is obtained under the pump power of 1.40 W. The flatness of the spectrum in the range of 700 nm~1600 nm is less than 5 dB (including the pump residue). The exceptional simplicity, economical efficiency and the comparable performances make the noise-like pulse oscillator a competitive candidate to the widely used cascade amplified coherent pulse as the pump source of broadband SC. To the best of our knowledge, this is the first demonstration of SC generation which is directly pumped by an all-fiber noise-like pulse oscillator.

## Area 13 - Optics

Short Papers
Paper Nr: 97
Title:

### Using Sum-Frequency Generation (SFG) to Probe Electric-Fields within Organic Field-Effect Transistors

Authors:

#### Douglas J. C. Gomes, Silvia G. Motti and Paulo B. Miranda

Abstract: Organic Field-Effect Transistors (OFETs) have attracted much research interest due to their potential for unique applications, such as flexible electronics. The operation of OFETs depends on the charge accumulation at the interface between an organic semiconductor and a dielectric material, induced by the voltage applied at the gate electrode. Direct measurements of the electric-field distribution in an operating device are useful for proposing and validating theoretical models for OFET operation. Here we propose using the second-order nonlinear optical process of Sum-Frequency Generation vibrational spectroscopy (SFG spectroscopy) to probe the presence of an electric-field in the dielectric layer of OFETs, in a noninvasive, non-destructive and remote fashion. The OFETs were fabricated with a dielectric layer consisting of poly(methyl-methacrylate) – PMMA, and an active layer based on poly(3-hexyl thiophene) – P3HT, and SFG spectra were acquired from the channel region of operating OFETs. It was observed the appearance of vibrational bands due to carbonyl groups (~ 1720 cm-1) of the PMMA layer, whose ?(2) were induced by the electric-field within the dielectric, similarly to a reversible poling of polymers. This phenomenon opens up the possibility of mapping the spatial charge distribution in the conducting channel using SFG microscopy in operating devices.

Posters
Paper Nr: 5
Title:

### Analysis on Output Polarization Characteristics of Fiber Comb Filters based on Polarization-Diversity Loop Structure

Authors:

#### Songhyun Jo, Kyoungsoo Park, Sung Wook Choi, Seul Lee Lee, Jun Hyeog Jeong, Jihoon Kim and Yong Wook Lee

Abstract: The output states of polarization (SOP’s) were investigated within the bandwidth of a filter channel (0.8 nm) for a variety of optical fiber comb filters based on polarization-diversity loop structure including a zeroth-order comb filter, first-order Lyot-type and Solc-type comb filters, and a second-order Solc-type comb filter. The output SOP’s (SOPout’s) of the filters were calculated at a flat-top band operation mode of each filter for four different input SOP’s (SOPin’s) except for the zeroth-order filter. It was found that the SOPout of each filter had unique dependence on wavelength. Specifically, the SOPout’s of first-order and second-order comb filters vary periodically with spectral periods of a channel bandwidth (0.8 nm) and its half (0.4 nm), respectively. If an output linear polarizer is located at the output port of each filter, the specific portion of transmission spectra can be passed or rejected, and the rejected band can be continuously tuned in a limited wavelength range by controlling the SOPin. Moreover, the SOPin can be figured out by analyzing the location of the spectral dip at the output transmission spectra obtained above by using the output polarizer.

Paper Nr: 10
Title:

### Two-photon Excitation of Hydrogen Atom by Sub-Femtoseconds Electromagnetic Pulses

Authors:

#### V. A. Astapenko and S. V. Sakhno

Abstract: The development of methods of generation of ultrashort pulses (USP) of femto- and attosecond duration ranges with controlled parameters necessitates the theoretical study of features of their interaction with a matter. Among such features that do not exist in case of “long” pulses should first of all be the nonlinear dependence of the photoprocess probability W on the USP duration as well as the dependence on the carrier phase with respect to the pulse envelope. It should be noted that if the dependence of the probability W on the phase manifests itself either only for very short pulses, when wt < 1 (w is carrier frequency of the pulse, t its duration), or in case of a nonlinear photoprocess, the function W(t) can differ from a linear function in the limit wt > 1 too for fields of moderate strength, when the perturbation theory is applicable. The present work is dedicated to the theoretical analysis of two-photon excitation of hydrogen atom in a discrete energy spectrum by ultrashort electromagnetic pulses of femto- and subfemtosecond ranges of durations. As examples, excitation of hydrogen atom from the ground state to excited states with a zero orbital moment is considered.

## Area 14 - Photonics

Posters
Paper Nr: 21
Title:

### New Materials for Photon Counting Avalanche Photodiodes

Authors:

#### Josef Blazej

Abstract: The experimental results acquired on avalanche photodiodes based on III-V semiconductor materials and operated as single photon counters with picosecond timing resolution are reported. The semiconductor structures fabricated on the basis of GaAs, GaP and GaAsP have been operated in a Geiger mode and employed in a photon counting experiment at the wavelengths from near ultraviolet to near infrared. The dark count rates, photon counting sensitivity and timing resolution have been measured for the experimental diode samples.

Paper Nr: 24
Title:

### Influence of 532 and 355 nm Nanosecond Laser Pulses on Photodestruction of Silver Nanoparticles in Photo-thermo-refractive Glasses

Authors:

#### Alexander Ignatiev, Dmitry Ignatiev, Dmitry Klyukin, Nikolay Nikonorov, Rustam Nuryev and Alexander Sidorov

Abstract: In this research we investigate an influence of wavelength of nanosecond laser radiation on the process of silver nanoparticles photodestruction in photo-thermo-refractive glass. Second and third harmonic of nanosecond YAG:Nd laser have been applied to irradiate photo-thermo-refractive silicate glasses with silver nanoparticles and different halogenides (F, Cl, Br) as dopants. Optical spectroscopy and X-ray diffraction analysis have revealed a presence of core/shell nanoparticles Ag/AgBr and Ag/Na0.8Ag0.2Cl. Irradiation of samples by third harmonic at 355 nm wavelength causes a red shift of surface plasmon resonance band (35 nm) whereas nanosecond laser radiation at 532 nm does not cause significant shift of the surface plasmon resonance band. Such a difference is caused by mechanisms involved in the photodestruction process.

## Area 15 - Optics

Posters
Paper Nr: 30
Title:

### Optimization of Non-diffractive Beam Propagation in Random Media Formed by Annular Beam

Authors:

#### Ziqi Peng and Tatsuo Shiina

Abstract: Light is quite difficult to propagate a long distance in random media such as human tissue or atmospheric dense cloud because of its scattering and absorption. For optical sensing, it is important to increase propagation efficiency which means expanding the sensing range. An annular beam can transform its waveform into a non-diffractive beam due to its propagation in a long distance. In our previous work, we found the annular beam also had non-diffractive effect when it propagated in diluted milk solution of a few tens centimetres at the concentration of less than 1%. In this study, to clear up how to control and optimize the non-diffractive effect of the annular beam in random media, numerical calculation of propagation characteristics of annular beam in air was estimated. The narrow annular beam with a small diameter would generate a high intensity non-diffractive beam at a short distance. We also had three sets of experiments of annular beam propagation in random media with the same view point as the calculation, but its propagation characteristics was evaluated by milk concentration. They showed the same variation of a non-diffractive beam with the result of numerical calculation in air. These results provide us a hint of optimization for annular beam propagation in random media.

## Area 16 - Lasers

Posters
Paper Nr: 34
Title:

### Nanosecond Pulse Generation near 1.55 Micron in the All-Fiber Figure-Eight Mode-Lock Laser with Passive Nonlinear Loop Mirror

Authors:

#### Svetlana S. Aleshkina, Mikhail M. Bubnov and Mikhail E. Likhachev

Abstract: Figure-eight mode-lock all-fiber laser based on a passive nonlinear loop mirror emitting nanosecond pulses at wavelength near 1.55 µm has been realized for the first time. Influence of the total laser dispersion on output characteristics of the laser has been studied. It is revealed that the main problem of utilization fibers with anomalous dispersion inside the passive nonlinear loop mirror is generation of low-energy optical solitons accompanied with nanosecond pulse break up. Solutions of this problem are discussed and stable laser schemes (i.e. all-polarization maintaining) are realized.

## Area 17 - Optics

Posters
Paper Nr: 36
Title:

### A Concept of Ultraviolet Lithography System and Design of its Rear Part using Artificial Intelligence for Starting Design

Authors:

#### Irina Livshits and Nenad Zoric

Abstract: This paper describes a concept for designing a projection lens in lithographic optical system for 365 nm. Our approach for meeting this objective is to use the starting design obtained by artificial intelligence mode in Synopsys software. The proposed method describes the steps of getting a desired starting point of the optical system and the optimization problems in the optical system with a high numerical aperture.

Paper Nr: 51
Title:

### Design and Analysis of a New Device for Low-Order Wavefront Aberrations Measurement

Authors:

#### Zhou Qiong, Liu Wenguang, Wang Gang, Yan Baozhu, Xi Fengjie and Jiang Zongfu

Abstract: For a high energy laser, thermally induced wavefront distortions include a large proportion of low-order aberrations with large peak-valley (PV) value.In this paper we design a Low-Order Wavefront Aberration Detector which can detect the large peak-valley value of low-order phase aberrations. Different from Shack–Hartmann Wavefront Sensor, this device includes one sepcial diaphragm, six sets of optical focusing system and six displacement detectors. The length of Low-Order Wavefront Aberration Detector can be controlled within 200mm. the minimum low-order aberration coefficient of LOWAD is less than 0.5λ which is determined by the inherent aberration distribution of optical focusing system. And we can choose reasonable position sensitve detector or four-quadrant photo-detector to detect relatiove displacement of each focal point, and thus the measurement sensitivity of LOWAD is less than 0.1λ and the measurement capability is more than 80λ. The new wavefront measurement device can be used to direct measure low-order aberrations for laser beam with large transverse area and do not need beam contracting system, and the size and cost is greatly below Shack–Hartmann Wavefront Sensor.

## Area 18 - Photonics

Posters
Paper Nr: 53
Title:

### Application of the Hamiltonian Formulation to Nonlinear Light-envelope Propagations

Authors:

#### Guo Liang, Qi Guo and Zhanmei Ren

Abstract: A new approach, which is based on the new canonical equations of Hamilton found by us recently, is presented to analytically obtain the approximate solution of the nonlocal nonlinear Schrödinger equation (NNLSE). The approximate analytical soliton solution of the NNLSE can be obtained, and the stability of the soliton can be analytically analysed in the simple way as well, all of which are consistent with the results published earlier. For the single light-envelope propagated in nonlocal nonlinear media modeled by the NNLSE, the Hamiltonian of the system can be constructed, which is the sum of the generalized kinetic energy and the generalized potential. The extreme point of the generalized potential corresponds to the soliton solution of the NNLSE. The soliton is stable when the generalized potential has the minimum, and unstable otherwise.

## Area 19 - Optics

Posters
Paper Nr: 54
Title:

### A Method to Improve the Precision of Interferometric Phase-recognization under Open-loop PZT Drive

Authors:

#### Liangen Yang, Xuanze Wang, Bingkang Liu, Zhongsheng Zhai and Tao He

Abstract: For the monochromatic light interferometry under open-loop PZT drive, a high precision method for phase recognization that satisfies the four steps phase-shift algorithm is proposed. The total idea of the phase recognization method is as follows. Firstly, two pixels with suitable phase-difference are selected from the interference field and the interference equations of the two pixels´ gray values are established in one driven cycle of PZT. Secondly, the parameters of interference equations can be obtained by using ellipse fitting algorithm. Thirdly, the point-to-point step length of PZT drive and sequence phases can be determined through reverse calculation of sequence phases. Finally, in order to calculate initial phase of every pixels four interference grayscale images that meet the four steps phase-shift algorithm are designed and calculated through Lagrange parabolic interpolation. The experimental results have shown that this method decreases the requirement for hardware, environment and needs less interference grayscale images than traditional methods. The method can meet the high precision demands of surface topography measurement and has high processing speed.

Paper Nr: 58
Title:

### A Portable, Low-cost System for Optical Explosive Detection based on a CMOS Camera

Authors:

#### Ross N. Gillanders, Iain A. Campbell, Fei Chen, Paulina O. Morawska, Ifor D. W. Samuel and Graham A. Turnbull

Abstract: Humanitarian demining requires a variety of methods and instrumentation for effective mine clearance, since a wide range of materials are used in mine manufacturing. However, landmines release vapours over time that can be detected, for example, by sniffer dogs. Optical sensor systems are especially suited to this application due to the potential for lightweight, portable, low-cost systems that nevertheless have fast response times and ppb-level sensitivity to explosive vapours. In this paper we present a system for detection based on a low-cost Raspberry Pi platform with an integrated CMOS camera. The conjugated polymers Super Yellow and Polyfluorene are excited by an LED, and the quenching effect by DNB vapour is monitored by the camera to indicate the presence of explosives. The system shows potential as a user-friendly, lightweight platform for explosive vapour sensing.

Paper Nr: 65
Title:

### Imaging Characteristics of the Axicon Imaging System

Authors:

#### Zhongsheng Zhai, Qinghua Lv, Xuanze Wang, Liangen Yang, Zhongbao Xu and He Tao

Abstract: The depth of an image system can be extended by an axicon which can generate line focus. According to physical optical theory, the diffracting patterns of the defocus point spread function (PSF) for the imaging system with axicon are analyzed through the generalize pupil function. The expressions of the PSF for the imaging system illuminated by white light are described as the superposition of the intensities in individual monochromatic patterns. Experimental results show that the central portion contains the most energy of the diffraction pattern from the PSF produced by the white light, and the contrast of secondary outside circular rings decreased rapidly. Furthermore,the central spot radius varied slowly with the increase of defocus parameter, and the depth of field of the imaging system is effectively extended with a shortcoming that the images need further processing.

Paper Nr: 75
Title:

### Design of Amorphous Silicon Photonic Crystal-based M-Z Modulator Operating at 1.55 µm

Authors:

#### Sandro Rao, Maurizio Casalino, Giuseppe Coppola, Rifat Kisacik, Tolga Tekin and Francesco G. Della Corte

Abstract: The design of an amorphous silicon-based Mach–Zehnder electro-optic modulator including two guiding p-i-n structures integrated inside a two-dimensional (2-D) photonic crystal (PhC) working at 1.55 µm, is reported. Electrically induced free carrier dispersion effect in this photonic material with a very cost-effective technology, is investigated for modulation. Our numerical analysis, performed by a time-domain (FDTD)-based software, proves that the voltage-length product can be remarkably reduced by taking advantage of both the strong PhC confinement and the wide refractive index tunability of amorphous silicon.

Paper Nr: 78
Title:

### Noise Influence on Low Contrast Image Correction for Soft X-Ray Projection Microscopy

Authors:

#### Erdenetogtokh Jamsranjav, Tatsuo Shiina, Kenichi Kuge, Atsushi Ito and Yasuhito Kinjo

Abstract: Soft X-ray projection microscopy has been developed for high magnified imaging of hydrated biological specimens because water window region is available. The projection microscopy is a simple optical layout and has advantages over other types of microscopes particularly for biological specimens because of its wide viewing area, easy zooming function and easy extension to CT. However the projection image is blurred by the diffraction of X-rays, resulting in the deterioration of the spatial resolution. In this study, the blurred images have been corrected by an iteration procedure, i.e., Fresnel and inverse Fresnel transformations are repeated. The correction was found to be not effective for every image, especially for images with low contrast. A contrast enhancement method prior to the iteration procedure was installed to make the iteration procedure more effective, but it was not enough yet due to the influence of background noise. We evaluated dependency between the background noise level and iteration effect in the cases with or without the contrast enhancement prior to the iteration procedure by simulation. We also demonstrated upper limits of the background noises which chromosome images are effectively corrected by the iteration procedure.

Paper Nr: 79
Title:

### Radio over Fiber Systems for Small Cell Wireless Communications

Authors:

#### Ajung Kim, K. Cho and J. Choi

Abstract: We established a radio over fiber system applicable to broadband wireless communications for small cell applications and to mobile fronthaul network segment in cloud-radio access networks (RAN). Optical radio signals are transmitted over a fronthaul fiber using orthogonal frequency division multiplexing (OFDM) techniques and subcarrier frequency division multiple access (SC-FDMA). System parameters are evaluated for various subcarrier modulations and the results of link performance measurements are analyzed.

Paper Nr: 85
Title:

### In-line Modal Couplers based on Multicore Fibers

Authors:

#### Youngbo Shim, Ju Il Hwang, Sang Gwon Song and Young-Geun Han

Abstract: We propose an in-line modal coupler based on a multicore fiber (MCF) which can be readily fabricated by using the adiabatic tapering method. The intermodal coupling of the in-line modal coupler apparently generated the transmission oscillation of the center core and the multiple side core modes depending on the waist diameter. The reduction of the waist diameter of the adiabatically tapered MCF could dramatically change its sensitivities to strain, temperature, and ambient index. We believe that experimental results are very useful to fabricate the in-line modal coupler based on the MCF and to improve the performance of the fiber-optic sensors by controlling the waist diameter of the adiabatically tapered MCF.

## Area 20 - Photonics

Posters
Paper Nr: 91
Title:

### Improvement of Perovskite Solar Cells Photovoltaic Performance by Localized Surface Plasmon Effect of Silver-alumina Core-shell Nanoparticles

Authors:

#### Marziyeh Yaghubinia, Majid Ebnali, Mahmoud Zendehdel and Mohammadreza Yaghoubinia

Abstract: Perovskite solar cells are new generation of nanostructure-based solar devices that could reach to highest efficiency records between third generation solar cells. In present project, for the first time, enhancement of the photovoltaic performance of planner perovskite solar cells is achieved by using localized surface Plasmon (LSP) effect of silver-alumina core-shell nanoparticles as a dopant in the perovskite layer. Photovoltaic performances of the devices are evaluated by FE-SEM, IV measurement, cyclic voltammetry, UV-Vis spectroscopy and electrochemical impedance spectroscopy. The results show significant increase of the overall efficiency and short-circuit current density of the devices by using LSP effect of Ag-Al2O3 nanoparticles.

Paper Nr: 99
Title:

### MMI Fiber Optic Refractometer with Universal pH Indicator Coating

Authors:

#### Adolfo Rodríguez-Rodríguez, René Domínguez-Cruz, Daniel May-Arrioja, Ignacio Matías-Maestro, Carlos Ruiz-Zamarreño and Francisco Arregui

Abstract: In this paper we show the preliminary results about fabrication of an optical fiber refractometer based on multimode interference effects (MMI) provided with Universal pH Indicator coating. The layer, deposited by coating dip-coating technique, allows increase the refractometer sensitivity which is around 344.5054 nm/RIU in a range of 1.333 to 1.4223. Highly repetitive and reversible refractometer have been achieved using a simple fabrication process. The device shown offers the possibility to be used as instrument to identify substances included aggressive liquids as gasoline.