PHOTOPTICS 2021 Abstracts

Area 1 - Lasers
Short Papers
Area 2 - Optics
Full Papers Short Papers
Area 3 - Photonics
Full Papers Short Papers

Area 1 - Lasers

Short Papers
Paper Nr: 12
Title:

Evaluation of Thermal Resistance of Surface-emitting Quantum Cascade Laser using Structural Function and 3D Thermal Flow Simulation
Authors:

Shigeyuki Takagi, Hirotaka Tanimura, Tsutomu Kakuno, Rei Hashimoto, Kei Kaneko and Shinji Saito
Abstract: We analysed the thermal characteristics of a surface-emitting quantum cascade laser (QCL), which is expected to increase output and improve beam quality, on the basis of structural functions and 3D thermal flow simulation. The surface-emitting QCL has a device size of 3 mm x 3 mm and has a photonic crystal for extracting laser light vertically from the QCL. The structural function indicating the heat capacity and thermal resistance of the surface-emitting QCL was measured by the static method, and the total thermal resistance including the mount was about 4.7 K/W. On the other hand, the thermal resistance calculated from the 3D thermal flow simulation of the surface-emitting QCL was 4.55 K/W, showing the results of the two methods to be in good agreement. It was shown that the structural function and the 3D simulation are effective for the thermal analysis of surface-emitting QCLs.
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Paper Nr: 27
Title:

Formation of Hybrid Resonators in the Semiconductor Circular Ring Laser Diode and Its Output Characteristics
Authors:

Chun T. Tsen, Ming C. Shih and Wen H. Lan
Abstract: We present the study of the emission characteristics of a semiconductor circular ring laser diode with a Y-junction output coupler. Instead of laser output from Y-junction coupling terminal, a confined laser beam output was also observed at non-waveguide region due to optical nonlinearity effect of the multi-quantum wells active median. It showed that except for the circular ring resonator mode, much complicate modes were excited from both output terminals. A hybrid resonator formed by conjugated reflection is suggested to explain the features of output characteristics. In addition, L-I and spectrum characteristics of both output terminals of these hybrid resonators were analysed to explore the detailed mechanism of these hybrid resonator.
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Area 2 - Optics

Full Papers
Paper Nr: 6
Title:

Numerical Simulated Concept and Mechanical Proof of Concept for a Transmission OCT (tOCT)
Authors:

Andreas Drauschke, Katharina Dettelbacher, Michaela Kienberger, Sarah Nagl and Christian Milz
Abstract: Optical coherence tomography is a very powerful tool in imaging methods, but its practical use is limited due to the shallow scan depth. A concept draft of a transmission OCT is presented, which eliminates the greatest limitation of the OCT – the small penetration depth. The functional principle, based on the basic structure of a Mach–Zehnder interferometer, is developed in a numerical simulation in OpticStudio. The numerical setup includes beam expander and beam compressor systems to maximize the contrast generated in the interference pattern and the design of an A–scan to realize a depth scan. As the result, the numerical simulation of the complete setup is presented and the concept is then demonstrated in a simplified mechanical setup without an A–scan.
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Paper Nr: 8
Title:

Moving Solitons in Coupled Bragg Gratings with a Uniform and a Nonuniform Bragg Gratings
Authors:

Md. B. Hossain and Javid Atai
Abstract: We consider the dynamics of moving solitons in a dual-core nonlinear system which consists of a uniform Bragg grating coupled with a nonuniform Bragg grating where nonuniformity is provided by dispersive reflectivity. It is found that moving solitons fill the entire bandgap. We also consider the effect of the dispersive reflectivity on the stability of the moving solitons.
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Paper Nr: 19
Title:

Strong Modulation of Absorption and Third-Harmonic Generation in Resonant Metasurfaces based on VO2
Authors:

Margherita Marni and Domenico de Ceglia
Abstract: Control of linear and nonlinear optical signals is of key importance in a variety of applications, including signal processing, optical computing and energy harvesting, to name just a few. Optical modulation and switching, and more generally tunability in photonic devices, are usually achieved in the visible and near-infrared range by carrier injection, chemical or mechanical activation, or by deploying materials with large electro-optic or optical nonlinear coefficients. However, these mechanisms are inherently weak and therefore require intense control signals in order to produce significant modulation effects. Here we adopt a nanophotonic solution in which a resonant film of a volatile phase-change material, vanadium dioxide, is inserted between an array of antennas and a metallic backplane. Our design takes advantage of (i) the large refractive-index change of VO2 at its insulator-to-metal transition and (ii) the field enhancements available when the Fabry-Pérot resonance of the film and the plasmonic resonance of the antennas are exited. In response to the VO2 phase transition, not only does our metasurface provide a strong and broadband modulation of linear absorption and reflection but it also shows a drastic variation of third-harmonic generation, with a conversion-efficiency contrast higher than three orders of magnitude.
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Paper Nr: 24
Title:

Nanosphere Photolithography: The Influence of Nanopore Arrays Disorder on Extraordinary Optical Transmission
Authors:

Andrei Ushkov, Olivier Dellea, Isabelle Verrier, Thomas Kampfe, Alexey Shcherbakov, Jean-Yves Michalon and Yves Jourlin
Abstract: We analyze both experimentally and numerically the influence of nanopore arrays disorder on extraordinary optical transmission in samples, fabricated via nanosphere photolithography. Two measures of disorder are considered, the correlations between them are discussed using experimental and numerical data. We propose a theoretical model which takes explicitly the disorder into account, and show how the concurrence between nanopore depth and disorder level defines the quality of EOT excitation. Simulated spectra are in a good agreement with experimental ones. Our results reveal the possibilities of NPL for EOT-based applications and pave the way toward plasmonic devices with a polycrystalline design.
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Paper Nr: 25
Title:

A Study on Enhanced Fluorescence Signal-to-noise by using the Stray Light Shutter for Quantitative PCR Chip
Authors:

Liang-Chieh Chao, Chun-Han Chou, Hsin-Yi Tsai, Kuo-Cheng Huang and Dar-Bin Shieh
Abstract: Quantitative polymerase chain reaction (qPCR) is the most important inspection technique for virus, especially for coronavirus disease, in this year. The qPCR chip and device were planned to develop because of the characteristics of fast inspection time, high accuracy and small system volume. Therein, the fluorescence intensity was the important signal in qPCR device, which represented the positive or negative reaction after the DNA was amplified and bound on the fluorescence dye, but the fluorescence signal was easily to be affected by the excitation and scattered light. The mini spectrometer was employed to receive the fluorescence intensity in PCR chip in this study, and the optical simulation was progressed, and the stray light shutter (SLS) was added to improve the signal-to-noise ratio (SNR) of fluorescence. The analysis results showed that the SNR of fluorescence can be enhanced from 3.14 to 16.78 by using the SLS with shape of extend component aperture, which the protruding structure was at the direction away from center. The results from this manuscript can provide the important reference information to the developer of qPCR chip, whom can obtain the high SNR fluorescence signal in qPCR inspection process for disease.
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Short Papers
Paper Nr: 7
Title:

High Uniformity Design of UV LED Illuminators for Exposure Equipment
Authors:

Chun-Han Chou, Yu-Hsuan Lin, Hsin-Yi Tsai, Ray-Ching Hong and Yi-Yung Chen
Abstract: We have presented the optical system design of control uniformity illumination system for stepper lithography. The illumination system acted a key factor in the lithography, because the output light source quality affected the exposure resolution and yield rate of products. The illumination system was composed by seven lens, imaging field was 12.6mm, chief ray angle was less than 0.4 degrees, distortion was less than 0.47% and numerical aperture was 0.1644. the irradiance flux of target area average was about 20 mW/cm2. The system’s uniformity deviation was less than ± 3 percentages. Each UV-LED of illumination system was individually controlled. It could make the imaging plane always have high uniformity to overcome the problem of light source attenuation.
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Paper Nr: 10
Title:

2D and 3D Measurement Algorithms for Real Front and Back Curved Surfaces of Contact Lenses
Authors:

Kentaro Saeki, Decai Huyan, Akira Nakamura, Shin Kubota, Kenji Uno, Kazuhiko Ohnuma and Tatsuo Shiina
Abstract: The 2D and 3D measurement algorithms for real front and back curved surfaces of contact lenses (CL) were developed. The purpose of 2D algorithm is to evaluate spherical lenses. We adopted the algorithm to be incident the probe light vertically along the curved surfaces of CLs under the condition that the difference of curvature radii between the front and back surfaces is small enough within numerical aperture (N.A.) of the optical probe. The vertical incidence against the curved surface is judged by using the intensity balance between OCT interference signals from both front and back surfaces of CL. As a result, the lens shape matched with the design value and RMSE of the thickness was 5.33 μm. Also, regarding the curvature radii, compatibility between this OCT device and the conventional device was indicated. In the 3D algorithm, we conducted a basic experiment using some special lenses in order to develop non-cylindrical lens measurement. By moving a 2-axis (vertical and horizontal) Micro Electro Mechanical System (MEMS) mirror with phase difference of 90,̊ it was designed to conduct circular scanning while maintaining vertical incidence of probe beam on the front surface of CL. The shape and the curvature radius was evaluated with simulation data under the same conditions. As a result, although it has an error against the design value, the result and the simulation result matched well.
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Paper Nr: 11
Title:

A Novel Approach for Experimental Earthquake Engineering Utilizing Mirror Reflections of Point Clouds Collected by Laser Scanner
Authors:

Shakhzod Takhirov, Mukhady Israilov and Sultan Kudratov
Abstract: A laser scanner is an optical instrument that emits laser beams toward objects surrounding the scanner and measures the location of the objects’ points in space. As a result, it collects the so-called point clouds. In experimental earthquake engineering, the laser scanners have been used in many applications. In quasi-static testing, they used for four-dimensional tracking of the test specimen's condition in three spatial coordinates and time. When a single scanner is used, the object's rear surface is in shadow zone and as such, the points of the rear surface are not collected. To acquire the point cloud of the object's rear side two commonly used options are utilized. In Option 1, several scanners working in parallel can be deployed. In Option 2, the same scanner can be moved to other positions to cover the shadow zones. Option 1 represents an expensive option that requires an investment in two or more scanners, finding a way of triggering them simultaneously, and time required for registration of the point clouds collected by several scanners. The main shortcoming of Option 2 is that is does not allow simultaneous scans from both sides and registration of the laser scans from many different points can be time consuming. To overcome shortcomings of these two options, this paper introduces a novel approach (Option 3) of using several mirrors strategically placed in respect to a single scanner to cover the shadow zones with a single scanner and from the same position. To ensure cost-effectiveness of the approach, this research was focused on the utilization of affordable and commonly used rear-reflective mirrors. This paper investigates the point clouds obtained from the mirror reflections and quantifies the quality of these data by estimating accuracy and reliability of the reflected point cloud data. The theoretical estimates were verified by laser scanning of sample test specimens.
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Paper Nr: 14
Title:

Performance Analysis of PAM4 Signal Transmission in Inter-datacenter Multicore Fiber Links Impaired by Inter-Core Crosstalk
Authors:

Rafael A. Dias, João L. Rebola and Adolfo T. Cartaxo
Abstract: In this work, we propose to use four-level pulse amplitude modulation (PAM4) and multicore fibers (MCFs) to support very high capacity inter-datacenter connections. The limitations imposed by inter-core crosstalk (ICXT) on the performance of 112 Gb/s up to 80 km-long optically amplified PAM4 inter-datacenter links with intensity-modulation and direct-detection (IM-DD) and full chromatic dispersion compensation in the optical domain are analyzed through numerical simulation. We show that those PAM4 inter-datacenter links achieve an outage probability (OP) of 10−4 with a maximum ICXT level of -13.9 dB for high skew-symbol rate products and require an ICXT level decrease of about 8.1 dB to achieve the same OP for low skew-symbol rate products. Due to using full dispersion compensation, the OP is not much affected by increasing the MCF length, from 10 km, where electrical noise significantly contributes to the performance degradation, to 80 km, where signal-amplified spontaneous emission beat noise is dominant. For an OP of 10−4, the maximum acceptable ICXT level shows only a 1.4 dB variation with the MCF length increase.
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Paper Nr: 15
Title:

Sparse Image Reconstruction for the SPIDER Optical Interferometric Telescope
Authors:

Luke Pratley and Jason D. Mcewen
Abstract: The concept of a recently proposed small-scale interferometric optical imaging device, an instrument known as the Segmented Planar Imaging Detector for Electro-optical Reconnaissance (SPIDER), is of great interest for its possible applications in astronomy and space science. Due to low weight, low power consumption, and high resolution, the SPIDER telescope could replace the large space telescopes that exist today. Unlike traditional optical interferometry the SPIDER accurately retrieves both phase and amplitude information, making the measurement process analogous to a radio interferometer. State of the art sparse radio interferometric image reconstruction techniques have been gaining traction in radio astronomy and reconstruct accurate images of the radio sky. In this work we describe algorithms from radio interferometric imaging and sparse image reconstruction and demonstrate their application to the SPIDER concept telescope through simulated observation and reconstruction of the optical sky. Such algorithms are important for providing high fidelity images from SPIDER observations, helping to power the SPIDER concept for scientific and astronomical analysis.
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Paper Nr: 17
Title:

Boundary Burr Phenomenon for Long-path Time Domain OCT
Authors:

Tatsuo Shiina
Abstract: Long-path OCT measurement system has been developed for industrial use. We aim to measure time change of the concentration and refractive index of the target solution with a certain volume. As the fundamental experiment, we put the glass plate in the solution to obtain the glass position and its thickness, and got the interesting result. That is, the vibration mitigating waveform like a diffraction pattern by a knife-edge was observed. The OCT measurement consists of inline signals from the back-reflected (scattered) light, the diffraction pattern by a knife-edge is appeared on a screen. Although this phenomenon causes the boundary burr on the target detection, while the diffraction pattern has the information of the refractive index difference of the target. In this study, the characteristics of the boundary burr phenomenon is examined. Its origin is considered experimentally and analytically.
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Paper Nr: 22
Title:

Short-reach 200 Gb/s SDM Network Employing Direct-detection and Optical SSBI Mitigation
Authors:

Tiago F. M., Tiago F. Alves and Adolfo T. Cartaxo
Abstract: We propose a new transmission scheme for direct-detection (DD) short-reach networks based on transmitting the carriers and the data signals in separated cores of a multicore-fibre (MCF). With this scheme, a low complexity signal-signal beat interference (SSBI) mitigation approach is proposed at the receiver side, which may be required to compensate electronically the chromatic dispersion of the singlemode fibre. The performance of a 200 Gb/s binary NRZ signal in a MCF short-reach network employing the proposed transmission scheme is assessed by numerical simulation. The combined effect of the skew and the laser phase noise on the system performance is evaluated. It is shown that the SSBI mitigation technique enables distances up to 180 m when dispersion is not compensated, showing the potential to be implemented in intra data-centre (DC) networks, when the signal mean optical power is much higher than the carrier mean optical power, and when the SSBI estimation is not corrupted by electrical noise. The results also show that in systems with full dispersion compensation, a significant performance improvement is achieved by the proposed SSBI mitigation approach, enabling higher connection lengths.
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Paper Nr: 28
Title:

Measuring Centers of Special Targets in Digital Still Images and Movie Frames: Approach and Evaluation
Authors:

Shakhzod Takhirov
Abstract: Digital cameras are undergoing explosive developments. As a result, high-resolution digital cameras have become very affordable, especially with the latest growth in smart phone technologies. Hence, the usage of existing measuring technologies and the development of new measuring technologies utilizing digital cameras is in high demand. This paper utilizes special black and white patterns, the so-called targets, to measure the relative displacement between two points. The paper introduces a new approach in measuring the location of their centers that is based on best fitting the transition zones to straight lines. The intersection of these lines produces the location of the center with sub-pixel accuracy. A special experimental rig was designed and built to evaluate the approach and compare the measurements to those obtained by a conventional position transducer connected to a data acquisition system. In the first part of the paper, the accuracy of the position transducer and the experimental setup is discussed. It is shown that the accuracy of the setup is much greater than the measurement expected from the digital images. Based on this, it was used as a reference system to evaluate the approach. In the second half of the paper, the approach is evaluated based on monitoring two targets. One of them is fixed and serves as a reference point, whereas another one is floating. The latter can move along the linear bearing system axis, which is orthogonal to the axis of the camera lens. The displacements of the floating target in respect to the fixed target were measured by a position transducer connected to a data acquisition system. The relative displacement of the floating target is captured by the digital camera and is based on the current location of the floating and fixed targets. This paper shows adequate accuracy of the approach and provides recommendations on the ways of keeping it at high accuracy for practical applications in experimental earthquake engineering.
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Area 3 - Photonics

Full Papers
Paper Nr: 5
Title:

Feature Extraction and Neural Network-based Analysis on Time-correlated LiDAR Histograms
Authors:

Gongbo Chen, Pierre Gembaczka, Christian Wiede and Rainer Kokozinski
Abstract: Time correlated single photon counting (TCSPC) is used to obtain the time-of-flight (TOF) information generated by single-photon avalanche diodes. With restricted measurements per histogram and the presence of high background light, it is challenging to obtain the TOF information in the statistical histogram. In order to improve the robustness under these conditions, the concept of machine learning is applied to the statistical histogram. Using the multi-peak extraction method, introduced by us, followed by the neural-network-based multi-peak analysis, the analysis and resources can be focused on a small amount of critical information in the histogram. Multiple possible TOF positions are evaluated and the correlated soft-decisions are assigned. The proposed method has higher robustness in allocating the coarse position (± 5 %) of TOF in harsh conditions than the case using classical digital processing. Thus, it can be applied to improve the system robustness, especially in the case of high background light.
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Paper Nr: 9
Title:

Effect of Phase Mismatch between the Bragg Gratings on the Stability of Gap Solitons in Semilinear Dual-core System
Authors:

Shuvashis Saha and Javid Atai
Abstract: The existence and stability of quiescent gap solitons are studied in a semilinear dual-core optical system, in which Bragg gratings (BGs) are written on the both cores with a phase shift and one core has the Kerr nonlinearity, while other one is linear. When the relative group velocity c in the linear core is zero, three separate band gaps are observed through the spectrum analysis, including one central band gap surrounded by upper and lower band gaps. Three band gaps are entirely filled with the stationary soliton solutions. However, in case of c is non-zero, only central band gap contains the stationary solution. Numerical techniques are used to find the stability of the quiescent gap solitons in terms of their frequency detuning.
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Short Papers
Paper Nr: 3
Title:

Metrology and Standardization of High Speed Pluggable Optical Interconnects
Authors:

Robert Ferguson, Irshaad Fatadin, Ka-Ming Liu, Irene Barbeito, Christian Hart, Richard Pitwon and David Robinson
Abstract: This paper describes research carried out under EURAMET project 14IND13 on the characterization of short- range optical interconnect technology. This paper aims to disseminate to the wider communications sector the primary importance of metrology and the need for standards associated with these emerging technologies. The focus of the research is the functional performance of embedded polymer waveguides. The results of various crucial parameters are described and their relevance and influence upon existing national and international standards discussed.
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Paper Nr: 16
Title:

Junction Temperature Measurement in Optically-Controlled Power Mosfet
Authors:

Sandro Rao, Elisa D. Mallemace, G. Cocorullo, L. Dehimi and Francesco G. Della Corte
Abstract: The temperature-dependent optical properties of silicon carbide (SiC), such as refractive index and reflectivity, have been used for a direct monitoring of the junction temperature of a power MOSFET. In particular, the optical response of a 4H-SiC MOSFET-integrated Fabry-Perot cavity to temperature changes has been investigated through parametric optical simulations at the wavelength of 450 nm. The reflected optical power exhibited oscillatory patterns caused by the multiple beam interference for which the MOSFET epilayer, between the gate-oxide and the doped 4H-SiC substrate, acts as a Fabry-Perot etalon. These results were used to calculate the refractive index change and, therefore, the optical phase shift of ∆φ= π/2 corresponding to a temperature variation that can be considered as a warning for the device “health”. In practical applications, the periodic monitoring of the optic spectrum at the interferometric structure output gives an essential information about the device operating temperature condition that, for high power operations, may lead to device damages or system failure.
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