[Editor's Pick] Current Optics and Photonics Vol. 8 no. 6 (2024 December)_2nd Binary-optimization-based Multilayers and Their Practical Applications Geon-Tae Park, Rira Kang, Byunghong Lee, and Sun-Kyung Kim* Current Optics and Photonics Vol. 8 No. 6 (2024 December), pp. 545-561 DOI: https://doi.org/10.3807/COPP.2024.8.6.545 Fig. 1 Workflow of binary-optimization-based multilayer design and its applications. (a) Schematic of the iterative optimization cycle, composed of four primary steps [53]. (b) (i) Schematic of antireflective coatings (ARC) applied to a lens, designed to minimize reflectance at the target wavelength λ0 over a wide range of incident angles θ. (ii) Illustration of transparent radiative coolers (TRCs) for energy-saving windows, engineered to reflect ultraviolet and near-infrared light while transmitting visible light, and maintaining high emissivity within the atmospheric window. The red line represents the target transmittance spectrum, and the blue line represents the target emissivity spectrum for an ideal transparent radiative cooler. (iii) Schematic of bandpass filters for thermophotovoltaics (TPVs), designed to enhance the efficiency of the photovoltaic (PV) cell by selective emission. The red dashed line represents the spectral irradiance of a blackbody IBB, and the blue solid line represents the external quantum efficiency (EQE) multiplied by the intensity of blackbody radiation (IBB). The green solid line shows the target spectrum of a selective emitter with unit emissivity. Keywords: Binary optimization, Machine learning, Multilayer, Optical coating, Optical design OCIS codes: (200.0200) Optics in computing; (220.0220) Optical design and fabrication; (310.0310) Thin films; (310.1210) Antireflection coatings; (310.6845) Thin film devices and applications Abstract Multilayers composed of two or more materials enable the regulation of transmission, reflection, and absorption spectra across one or multiple bands. While analytic formulas based on well-established interference conditions, such as those employed in single-, double-, and triple-layer antireflective coatings and distributed Bragg reflectors, have provided suitable solutions for traditional optical coatings, they are limited in achieving the intricate spectral characteristics required by multifunctional optical coatings. To overcome this limitation, a variety of machine learning-based design algorithms have been rigorously studied. Among these, binary optimization has proven particularly effective for designing multilayer optical coatings. This approach transforms a given multilayer into a binary vector with multiple bits, where each bit represents one of the constituent materials, and quickly identifies an optimal figureof-merit by analyzing the interactions among the elements of the binary vector. In this review article, we elucidate the principles of binary optimization and explore its applications in the design of multilayers for antireflective coatings for high-numerical-aperture lenses, transparent radiative coolers for energysaving windows, and bandpass filters for thermophotovoltaics. Furthermore, we address the limitations, challenges, and perspectives of machine learning-based optical design to guide directions for future research in this field. [Editor's Pick] Current Optics and Photonics Vol. 8 no. 6 (2024 December)_1st A Tutorial on Inverse Design Methods for Metasurfaces Jin-Young Jeong† , Sabiha Latif† , and Sunae So* Current Optics and Photonics Vol. 8 No. 6 (2024 December), pp. 531-544 DOI: https://doi.org/10.3807/COPP.2024.8.6.531 Fig. 1 Schematic illustration of an overview of inverse design metasurfaces using machine learning and optimization methods. Keywords: Inverse design, Machine learning, Metasurface, Optimization algorithm OCIS codes: (150.1135) Algorithms; (240.0240) Optics at surfaces Abstract This paper provides a tutorial on inverse design approaches for metasurfaces with a systematic analysis of the fundamental methodologies and underlying principles for achieving targeted optical properties. Traditionally, metasurfaces have been designed with extensive trial-and-error methods using analytical modeling and numerical simulations. However, as metasurface complexity grows, these conventional techniques become increasingly inefficient in exploring the vast design space. Recently, machine learning and optimization algorithms have emerged as powerful tools for overcoming these challenges and enabling more efficient and accurate inverse design. We begin by introducing the fundamentals of optical simulations used for forward modeling of metasurfaces and their relevance to inverse design. Next, we explore recent advancements in applying machine learning techniques such as neural networks, Markov decision processes, and Monte Carlo simulations, as well as optimization algorithms, including automatic differentiation, the adjoint method, genetic algorithms, and particle swarm optimizations, and show their potential to revolutionize the metasurface design process. Finally, we conclude with a summary of key findings and insights from this review. [하이라이트 논문] 한국광학회지 Vol. 35 No.6 (2024 December) Recent Trends in Bioinspired Camera Systems for Intelligent Robotics 지능형 로봇을 위한 생체모사형 카메라 연구 최신 지견 장진영1ㆍ장세희1ㆍ송영민1,2,3† 한국광학회지 Vol. 35 No.6 (2024 December) pp. 265-375 DOI: https://doi.org/10.3807/KJOP.2024.35.6.265 Fig. 1 (a) Photograph of the tunable hemispherical electronic eye camera system. (b) Photographs of the photodiode array imaged through a lens at different magnifications (left: smaller radius of curvature, right: larger radius of curvature). (c) Image demonstration of a test pattern (left: flat detector, right: detector shape matched to the Petzval surface). (a)–(c) are reprinted from I. Jung et al. Proc. Natl. Acad. Sci. 2011; 108; 1788-1793. Copyright © 2011, National Academy of Sciences [2] . (d) Optical layout showing a monocentric imager designed with a single ball lens. (e) Photographs of the five-gore structure before mounting and curved device positioned in a hemispherical fixture. (d) and (e) are reprinted from T. Wu et al. Microsyst. Nanoeng. 2016; 2; 16019. Copyright © 2016, T. Wu et al. [3] . (f) Photograph of the phototransistor array on a planar substrate. The inset shows an exploded schematic view of a phototransistor structure. (f) is reprinted from C. Choi et al. Nat. Commun. 2017; 8; 1664. Copyright © 2017, C. Choi et al. [6] . (g) Curvature forming method using two axisymmetric models of a spherical wrapping process. (h) Photograph of a curved complementary metal oxide semiconductor (CMOS) image sensor. (g) and (h) are reprinted with permission from Guenter et al. Opt. Express 2017; 25; 13010-13023. Copyright © 2017, Optical Society of America [8]. Keywords: 생체모사형 카메라, 이미지 센서, 비전 시스템 OCIS codes: (040.1490) Cameras; (110.0110) Imaging systems; (220.0220) Optical design and fabrication 초록 지능형 로봇 시대가 도래함에 따라 이미지 센서 또는 카메라 모듈에도 각 수요처에 따른 제품군의 다양화 필요성이 대두되고 있다. 이와 동시에 초소형/저전력 구동부터 하드웨어 레벨 물체 인식까지, 기존 카메라에서 구현하기 어려운 성능에 대한 수요도 늘고 있다. 한편 인간의 눈을 비롯한 자연계 동물의 눈 구조 및 기능의 우수함과 다양성은 미래 비전 시스템 개발에 큰 영감을 준다. 특히 동물의 서식지 및 생활 환경에 적응하기 위해 생태학적으로 진화한 눈에는 기존의 카메라에서 볼 수 없던 기능이 다수 존재하기 때문에, 최근 이를 모방하기 위한 연구가 활발히 이루어지고 있다. 이러한 생체모사형 카메라의 분야는 크게 렌즈 광학계, 이미지 센서, 나노포토닉 구조, 뉴런/시냅스 모사로 나눌 수 있으며, 최근에는 이를 모두 통합하여 하나의 완성된 비전 시스템을 만들기 위한 시도가 이루어지고 있다. 본 리뷰에서는 세부기술별로 나누어 연구 동향을 살피기보다는, 기술의 발전 방향에 따른 생체모사형 카메라 연구의 흐름을 추적하고자 한다. Abstract With the advent of the intelligent robotics era, there is an increasing demand for a variety of image sensors and camera modules to meet the needs of various applications. At the same time, demand is growing for performance such as ultra-compact size, low-power operation, and hardware-level object recognition that is difficult to achieve with existing cameras. The superior structures and functionalities of natural eyes, including those of humans and other animals, provide significant inspiration for the development of next-generation artificial vision systems. In particular, the unique characteristics of animal eyes, which have evolved ecologically to adapt to specific habitats and environments, exhibit functionalities beyond those found in conventional cameras. Consequently, research aiming to mimic these natural optical systems has become very active. Bioinspired cameras can generally be categorized into lens optics, image sensors, nanophotonic structures, and neuron/synapse mimics. Recently, there have been attempts to integrate all these components into a complete vision system. This review aims to trace trends in bioinspired cameras, focusing not on the technical aspects of individual components but on overall directions in technological advancement. [하이라이트 논문] 한국광학회지 Vol. 35 No.5 (2024 Ocotber) Soliton Mode-locking and Numerical Analysis of Yb3+-doped Potassium Double Tungstate Lasers in Compact Laser Cavity Geometries Yb3+ 도핑된 칼륨 이중 텅스테이트 결정을 이용한 소형 공진기에서의 솔리톤 모드 잠금 레이저 구현 및 수치 해석 김덕우 ㆍ고광훈ㆍ이상민† 한국광학회지 Vol. 35 No.5 (2024 October) pp. 241-249 DOI: https://doi.org/10.3807/KJOP.2024.35.5.241 Fig. 1 Schematic of experimental setup. LD, polarization maintaining fiber-coupled laser diode; COL, fiber collimator (NA = 0.50); HWP, half-wave plate; Lens, pump focusing lens with a focal length of 50 mm; M 1,2 , concave mirrors with a radius of curvature of 50 mm; OC, output coupler; CM, GTI chirped mirror; C, laser crystal. Keywords: 펨토초 레이저, 모드 잠금, 이터븀 OCIS codes: (140.3580) Lasers, solid-state; (140.3615) Lasers, ytterbium; (140.4050) Mode-locked lasers; (140.7090) Ultrafast lasers; (190.5530) Pulse propagation and temporal solitons 초록 본 연구에서는 Yb3+ 이온이 도핑된 세 종류의 이중 텅스텐 결정, Yb:KGdW, Yb:KYW 및 Yb:KLuW을 사용하여 1039 nm의 중심파장 영역에서 반복율이 405 MHz인 연속파 모드 잠금된 소형 고체 레이저를 구현하였다. 모드 잠금을 위한 광스위칭 소자로 반도체 포화 흡수체 거울을 사용하였고, 모드 잠금 상태들은 세 결정 모두에서 수 시간 이상 Q-스위칭 불안정성 없이 안정적으로 동작하였다. 특히 Yb:KGdW 결정을 이용한 레이저는 최고 출력 125 mW에서 108 fs의 펄스폭을 갖는 펄스를 방출하였다. 또한 표준 분할 단계 푸리에 방법을 이용하여 공진기의 군지연 분산 및 자체 위상 변조를 고려한 Haus Master 방정식을 수치 해석으로 풀고, 그 결과를 실험결과와 비교 및 분석하였다. Abstract In this study, we demonstrate compact mode-locked laser operations using three different kinds of Yb3+-doped potassium double tungstate laser crystals, Yb:KGdW, Yb:KYW and Yb:KLuW, operating near 1040 nm at a repetition rate of 405 MHz. We utilized a semiconductor saturable absorber mirror (SESAM) as a mode locker, successfully maintaining mode-locked states for several hours without any Q-switching instabilities for all types of laser crystals. Notably, the Yb:KGdW mode-locked laser produces the shortest pulse with a duration of 108 fs, delivering 125 mW of output power. Additionally, we conducted a numerical analysis by solving the Haus Master equation, which incorporates the effect of group delay dispersion and self-phase modulation, using the standard split-step Fourier method. [Editor's Pick] Current Optics and Photonics Vol. 8 no. 5 (2024 October) Cell Death Inhibition Effect of Antioxidant Activity by 630 and 850 nm LEDs in RAW264.7 Cells Hee Eun Kim, Eun Young Kim>, Jin Chul Ahn*, and Sang Joon Mo** Current Optics and Photonics Vol. 8 No. 5 (2024 October), pp. 441-455 DOI: https://doi.org/10.3807/COPP.2024.8.5.441 Fig. 1 Photographs showing the lighting conditions during exposure of RAW264.7 cells to red (left) and near-infrared (right) LED lights. LED devices for a cell culture plate with an output irradiance of 10 mW/cm2 light at a distance of 5 cm. To cool the LED board, a cooling fan is installed to control temperature rise. Keywords: Antioxidant activity, Cell death, Light-emitting diode, RAW264.7 cell OCIS codes: (000.1430) Biology and medicine; (170.0170) Medical optics and biotechnology; (170.1420) Biology; (170.1610) Clinical applications Abstract This study objective was to evaluate the effects and mechanisms of low-level laser therapy in H2O2-induced cell death in mouse macrophage RAW264.7 cell. After irradiation with 630 and 850 nm wavelength diode lasers with an intensity of 10 mW/cm2 in RAW264.7 cells treated with 0.7 Mm H2O2, the effects and mechanisms of the two wavelengths on cell death inhibition were evaluated using MTT assay, ROS staining, TUNEL assay, flow cytometry analysis, and Western blot analysis. As a result, 630 or 850 nm light-emitting diodes (LED) were irradiated for 10 or 40 minutes to increase cell viability with H2O2 by about 1.7- or 1.6-fold, respectively. In addition, irradiation with two LEDs showed significant ROS scavenging effects, and TUNEL-positive cells were significantly reduced by 45.7% (630 nm) and 37.8% (850 nm) compared to cells treated with H2O2 alone. The Bax/Bcl-2 ratio of cells irradiated with both LEDs was significantly lower than that of cells treated with H2O2 only, and the expression of procaspase-3 and cleaved PARP was also significantly expressed in the direction of suppressing cell death. In conclusion, ROS scavenging activity by both LEDs irradiation leads to the expression of cell death pathway proteins in the direction of inhibiting cell death. [하이라이트 논문] 한국광학회지 Vol. 35 No.4 (2024 August) Hyperlens and Metalens-based Biomedical Imaging 하이퍼렌즈 및 메타렌즈 기반 바이오메디컬 이미징 박혜미1,2 *ㆍ조용재1 *ㆍ김인기1,2† 한국광학회지 Vol. 35 No.4 (2024 August) pp. 135-142 DOI: https://doi.org/10.3807/KJOP.2024.35.4.135 Fig. 1 Examples of metamaterials operating at various wavelengths. The working mechanism and operation wavelength vary depending on the materials and structures. (a) V-shaped antenna metamaterial fabricated on a silicon wafer. Reprinted with permission from N. Yu et al. Science 2011; 334; 333-337. Copyright © 2011, The American Association for the Advancement of Science [7] . (b), (c) Scanning electron microscope images of square-shaped crystalline silicon metamaterials. Reprinted with permission from H. Liang et al. Nano Lett. 2018; 18; 4460-4466. Copyright © 2018, American Chemical Society [8] . (d) Chiral metamaterial fabricated by electron beam lithography. Scale bar: 500 nm. Reprinted with permission from [9] Copyright © 2007, Optical Society of America. (e) Fishnet structure metamaterial fabricated by nanoimprint lithography. Reprinted with permission from W. Wu et al. Appl. Phys. A 2007; 87; 143-150. Copyright © 2007, Springer-Verlag [10] . (f) Scanning electron microscope images of hyperbolic metamaterials composed of silver/germanium multilayers, shown with two, three, and four pairs of layers, respectively. Reprinted with permission from X. Yang et al. Nat. Photonics 2012; 6; 450-454. Copyright © 2012, Springer Nature Limited [11] . Keywords: 바이오 메디컬 이미징, 하이퍼렌즈, 메타렌즈, 메타물질 OCIS codes: (160.3918) Metamaterials; (170.3880) Medical and biological imaging; (220.0220) Optical design and fabrication 초록 바이오 메디컬 이미징 기술은 생물학적 연구 및 의료 기술에 사용되는 이미징 기법으로서 생물학적 과정, 구조 및 상태를 탐구하는 데 필수이 며, 질병의 조기 진단과 치료법 개발에도 중요한 역할을 하고 있다. 그중에서도 특히 빛을 이용한 광학 이미징 기술은 생물학 연구에서 가장 많이 활용되고 활발하게 연구되고 있다. 광학 이미징 기술의 발전에 가장 큰 걸림돌이 되고 있는 것은 해상도 및 빛의 투과 깊이 한계 등의 문제 인데, 최근에는 메타물질을 이용하여 이를 해결하고자 하는 연구가 활발해지고 있는 추세이다. 메타물질은 나노구조체의 규칙적인 배열을 통해 빛의 성질을 자유롭게 조절하는 물질로서, 이미징 분야에서는 이미 혁신적인 도구로 자리잡고 있다. 이 글에서는 메타물질을 활용한 광학 이미징 기술의 작동 원리와 주요 응용 사례에 대해 자세히 소개하고자 한다 Abstract Biomedical imaging technologies refer to imaging techniques used in biological research and medical technology that are essential for exploring biological processes, structures, and conditions. They also play a crucial role in the early diagnosis of diseases and the development of treatments. Optical imaging technologies, in particular, are the most widely used and actively researched in biological studies. The major obstacles to technological advancement are the limitations in resolution and light penetration depth. Recently, many technologies have been studied to overcome these limitations using metamaterials. These are materials that can freely manipulate the properties of light through the regular arrangement of nanostructures and have established themselves as innovative tools in the imaging field. This article aims to provide a detailed introduction to the working principles and key applications of these technologies. [Editor's Pick] Current Optics and Photonics Vol. 8 no. 4 (2024 August) Utilizing Optical Phantoms for Biomedical-optics Technology:Recent Advances and Challenges Ik Hwan Kwon1†, Hoon-Sup Kim1†, Do Yeon Kim1,2†, Hyun-Ji Lee1,3†, and Sang-Won Lee1,3,4 * Current Optics and Photonics Vol. 8 No. 4 (2024 August), pp. 327-344 DOI: https://doi.org/10.3807/COPP.2024.8.4.327 Fig. 1 Phantoms of optical coherence tomography (OCT) for image calibration and functional quality test. (a) The OCT image and graphs of a single-layer phantom. The nano phantom consists of ultra violet (UV)-curing epoxy and nano-shells to compare the performance of the four OCT systems. Reprinted with permission from A. Fouad et al. Biomed. Opt. Express [1]. Copyright © 2014, Optica Publishing Group. (b) Schematic and OCT images of multi-layer phantoms. Reprinted with permission from A.Agrawal et al. Biomed. Opt. Express [3]. Copyright © 2013, Optica Publishing Group. (c) Wave propagation pattern of phantom from optical coherence elastography. Reprinted from S. Song et al. J. Biomed. Opt. 2013; 18; 21509. Copyright © 2013, SPIE [60]. (d) Spectroscopic OCT image and map of spectroscopic metrics of the phantom. See the main text for details. Reprinted with permission from V. Jaedicke et al. Biomed. Opt. Express [37]. Copyright © 2013, Optica Publishing Group. Keywords: Calibration, Evaluation, Optical phantom, Tissue-mimic OCIS codes: (120.4800) Optical standards and testing; (170.0110) Imaging systems; (170.0170) Medical optics and biotechnology; (170.3890) Medical optics instrumentation;(220.0220) Optical design and fabrication Abstract Optical phantoms are essential in optical imaging and measurement instruments for performance evaluation, calibration, and quality control. They enable precise measurement of image resolution, accuracy, sensitivity, and contrast, which are crucial for both research and clinical diagnostics. This paper reviews the recent advancements and challenges in phantoms for optical coherence tomography, photoacoustic imaging, digital holographic microscopy, optical diffraction tomography, and oximetry tools. We explore the fundamental principles of each technology, the key factors in phantom development, and the evaluation criteria. Additionally, we discuss the application of phantoms used for enhancing opticalimage quality. This investigation includes the development of realistic biological and clinical tissuemimicking phantoms, emphasizing their role in improving the accuracy and reliability of optical imaging and measurement instruments in biomedical and clinical research. [하이라이트 논문] 한국광학회지 Vol. 35 No.3 (2024 June) Fabrication and Optical Characterization of Highly Dy3+-ion Incorporated Alumino-borosilicate Glasses for Magneto-optical Applications at 1550 nm 1550 nm 자기광학 응용을 위한 고농도 Dy3+ 이온이 함유된 알루미노보로실리케이트 유리의 제조 및 자기광학 특성 분석 카다탈라 린가나ㆍ류용탁ㆍ박영욱ㆍ유봉안ㆍ김복현1† 한국광학회지 Vol. 35 No.3 (2024 June) pp. 115-120 DOI: https://doi.org/10.3807/KJOP.2024.35.3.115 Fig. 1 Highly Dy3+-ion incorporated alumino-borosilicate glass samples fabricated by melt quenching process using an electric furnace (glass sample size: 10 × 10 × 15 mm3). Keywords: 알루미노보로실리케이트 유리, 디스프로슘 이온(Dy3+), 광특성, 자기광학 효과, 베르데 상수 OCIS codes: (160.2750) Glass and other amorphous; (160.5690) Rare-earth-doped materials; (230.2240) Faraday effect; (210.3810) Magneto-optic systems; (160.4760) Optical properties 초록 자기광학(magneto-optical, MO) 효과가 우수한 광학소재는 자기장센서, 광전류센서, 광 고립기(optical isolator), 그리고 광서큘레이터와 같은 다양한 응용 분야에서 활용될 수 있어 많은 관심을 받고 있다. 본 연구에서는 일반적인 유리용융법을 사용하여 Dy3+ 이온이 고농도로 함유된 알루미노보로실리케이트(alumino-borosilicate, ABS) 광학유리를 제조하고, Dy3+ 이온 농도에 따른 ABS-Dy 유리의 열 특성, 광 특성 및 자기광학 특성을 분석하였으며 1550 nm 파장 대역에서 유리의 MO 특성을 패러데이 회전각 측정을 통하여 분석하였다. 패러데이 회전 각은 유리의 Dy3+ 이온 농도가 증가함에 따라 선형적으로 증가하는 것으로 나타났으며, 특히 Dy2O3 함량이 30 mol%인 유리는 −6.86 rad/ (T·m) 가량의 높은 베르데 상수를 갖는 것으로 확인되었다. 또한 제조된 ABS-Dy 유리는 128 ℃ 이상의 우수한 열안정성(∆T = Tx − Tg)과 파장 대역이 각각 490–710, 1390–1560, 1800–2400 nm일 때 70% 이상의 높은 광투과특성을 보여주었다. 이상의 높은 베르데 상수와 우수한 열안정성은 본 연구에서 제안한 ABS-Dy 유리가 1550 nm MO 소자용 광학소재로 사용 가능함을 시사한다. Abstract Magneto-optical (MO) materials have attracted much attention, since they can be utilized for various optical applications, such as magnetic field sensors, optical current sensors, optical isolators, and optical circulators. In this study, alumino-borosilicate (ABS) glasses with high concentrations of Dy3+ ions were fabricated by a conventional melt-quenching technique, and the dependence of their thermal, optical, and magneto-optical properties on Dy3+-ion concentration was investigated. The MO property of the glasses was investigated by measurement of Faraday rotation at 1550 nm. The Faraday rotation angle increased linearly with the increase of Dy3+-ion concentration in the glasses. A very high Verdet constant of −6.86 rad/(T·m) was obtained for glass with a Dy 3+ -ion concentration of 30 mol%. In addition, the ABS-Dy glasses showed good thermal stability of greater than 128 ℃ against crystallization, and high optical transmission of 70% in the visible to near-infrared windows of 480–720, 1390–1560, and 1800–2400 nm. Due to the high Verdet constant and good thermal stability, the ABS-Dy glasses in this study could be candidate optical materials for MO device applications at 1550 nm. [Editor's Pick] Current Optics and Photonics Vol. 8 no. 3 (2024 June) Fabrication of Phase Plate to Simulate Turbulence Effects on an Optical Imaging System in Strong Atmospheric Conditions Han-Gyol Oh1,2, Pilseong Kang1, Jaehyun Lee1, Hyug-Gyo Rhee1,2 *, Young-Sik Ghim1,2 **, and Jun Ho Lee3 Current Optics and Photonics Vol. 8 No. 3 (2024 June), pp. 259-269 DOI: https://doi.org/10.3807/COPP.2024.8.3.259 Fig. 1 Schematic diagram of (a) effect of turbulence layer (atmosphere) in the telescope, (b) adaptive optics (AO) system using an optical phase plate (OPP) as the turbulence layer. Keywords: Adaptive optics, Air disturbance, Fabrication, Optical phase plate OCIS codes: (010.1330) Atmospheric turbulence; (220.1080) Active or adaptive optics; (220.4610) Optical fabrication Abstract Optical imaging systems that operate through atmospheric pathways often suffer from image degradation, mainly caused by the distortion of light waves due to turbulence in the atmosphere. Adaptive optics technology can be used to correct the image distortion caused by atmospheric disturbances. However, there are challenges in conducting experiments with strong atmospheric conditions. An optical phase plate (OPP) is a device that can simulate real atmospheric conditions in a lab setting. We suggest a novel two-step process to fabricate an OPP capable of simulating the effects of atmospheric turbulence. The proposed fabrication method simplifies the process by eliminating additional activities such as phase-screen design and phase simulation. This enables an efficient and economical fabrication of the OPP. We conducted our analysis using the statistical fluctuations of the refractive index and applied modal expansion using Kolmogorov’s theory. The experiment aims to fabricate an OPP with parameters D/r0 ≈ 30 and r0 ≈ 5 cm. The objective is defined with the strong atmospheric conditions. Finally, we have fabricated an OPP that satisfied the desired objectives. The OPP closely simulate turbulence to real atmospheric conditions. [Editor's Pick] Current Optics and Photonics Vol. 8 no. 2 (2024 April) Quantifying Aberrations on Object Plane Using Zernike Polynomials Yohan Kim1 *, Theo Nam Sohn2, Cheong Soo Seo1, and Jin Young Sohn1 Current Optics and Photonics Vol. 8 No. 2 (2024 April), pp. 151-155 DOI: https://doi.org/10.3807/COPP.2024.8.2.151 Fig. 1 Optical layout of 1.5× magnification WiseScope. LED, light-emitting diode; PBS, polarizing beam splitter. Keywords: Focus measure, Optical aberration, Wavefront error, Zernike polynomials OCIS codes: (010.7350) Wave-front sensing; (080.1010) Aberrations (global); (100.2550) Focalplane-array image processors; (110.0110) Imaging systems; (120.4640) Optical instruments Abstract Optical systems often suffer from optical aberrations caused by imperfect hardware, which places significant constraints on their utility and performance. To reduce these undesirable effects, a comprehensive understanding of the aberrations inherent to optical systems is needed. This article presents an effective method for aberration detection using Zernike polynomials. The process involves scanning the object plane to identify the optimal focus and subsequently fitting the acquired focus data to Zernike polynomials. This fitting procedure facilitates the analysis of various aberrations in the optical system. 12345
[Editor's Pick] Current Optics and Photonics Vol. 8 no. 6 (2024 December)_2nd Binary-optimization-based Multilayers and Their Practical Applications Geon-Tae Park, Rira Kang, Byunghong Lee, and Sun-Kyung Kim* Current Optics and Photonics Vol. 8 No. 6 (2024 December), pp. 545-561 DOI: https://doi.org/10.3807/COPP.2024.8.6.545 Fig. 1 Workflow of binary-optimization-based multilayer design and its applications. (a) Schematic of the iterative optimization cycle, composed of four primary steps [53]. (b) (i) Schematic of antireflective coatings (ARC) applied to a lens, designed to minimize reflectance at the target wavelength λ0 over a wide range of incident angles θ. (ii) Illustration of transparent radiative coolers (TRCs) for energy-saving windows, engineered to reflect ultraviolet and near-infrared light while transmitting visible light, and maintaining high emissivity within the atmospheric window. The red line represents the target transmittance spectrum, and the blue line represents the target emissivity spectrum for an ideal transparent radiative cooler. (iii) Schematic of bandpass filters for thermophotovoltaics (TPVs), designed to enhance the efficiency of the photovoltaic (PV) cell by selective emission. The red dashed line represents the spectral irradiance of a blackbody IBB, and the blue solid line represents the external quantum efficiency (EQE) multiplied by the intensity of blackbody radiation (IBB). The green solid line shows the target spectrum of a selective emitter with unit emissivity. Keywords: Binary optimization, Machine learning, Multilayer, Optical coating, Optical design OCIS codes: (200.0200) Optics in computing; (220.0220) Optical design and fabrication; (310.0310) Thin films; (310.1210) Antireflection coatings; (310.6845) Thin film devices and applications Abstract Multilayers composed of two or more materials enable the regulation of transmission, reflection, and absorption spectra across one or multiple bands. While analytic formulas based on well-established interference conditions, such as those employed in single-, double-, and triple-layer antireflective coatings and distributed Bragg reflectors, have provided suitable solutions for traditional optical coatings, they are limited in achieving the intricate spectral characteristics required by multifunctional optical coatings. To overcome this limitation, a variety of machine learning-based design algorithms have been rigorously studied. Among these, binary optimization has proven particularly effective for designing multilayer optical coatings. This approach transforms a given multilayer into a binary vector with multiple bits, where each bit represents one of the constituent materials, and quickly identifies an optimal figureof-merit by analyzing the interactions among the elements of the binary vector. In this review article, we elucidate the principles of binary optimization and explore its applications in the design of multilayers for antireflective coatings for high-numerical-aperture lenses, transparent radiative coolers for energysaving windows, and bandpass filters for thermophotovoltaics. Furthermore, we address the limitations, challenges, and perspectives of machine learning-based optical design to guide directions for future research in this field. [Editor's Pick] Current Optics and Photonics Vol. 8 no. 6 (2024 December)_1st A Tutorial on Inverse Design Methods for Metasurfaces Jin-Young Jeong† , Sabiha Latif† , and Sunae So* Current Optics and Photonics Vol. 8 No. 6 (2024 December), pp. 531-544 DOI: https://doi.org/10.3807/COPP.2024.8.6.531 Fig. 1 Schematic illustration of an overview of inverse design metasurfaces using machine learning and optimization methods. Keywords: Inverse design, Machine learning, Metasurface, Optimization algorithm OCIS codes: (150.1135) Algorithms; (240.0240) Optics at surfaces Abstract This paper provides a tutorial on inverse design approaches for metasurfaces with a systematic analysis of the fundamental methodologies and underlying principles for achieving targeted optical properties. Traditionally, metasurfaces have been designed with extensive trial-and-error methods using analytical modeling and numerical simulations. However, as metasurface complexity grows, these conventional techniques become increasingly inefficient in exploring the vast design space. Recently, machine learning and optimization algorithms have emerged as powerful tools for overcoming these challenges and enabling more efficient and accurate inverse design. We begin by introducing the fundamentals of optical simulations used for forward modeling of metasurfaces and their relevance to inverse design. Next, we explore recent advancements in applying machine learning techniques such as neural networks, Markov decision processes, and Monte Carlo simulations, as well as optimization algorithms, including automatic differentiation, the adjoint method, genetic algorithms, and particle swarm optimizations, and show their potential to revolutionize the metasurface design process. Finally, we conclude with a summary of key findings and insights from this review. [하이라이트 논문] 한국광학회지 Vol. 35 No.6 (2024 December) Recent Trends in Bioinspired Camera Systems for Intelligent Robotics 지능형 로봇을 위한 생체모사형 카메라 연구 최신 지견 장진영1ㆍ장세희1ㆍ송영민1,2,3† 한국광학회지 Vol. 35 No.6 (2024 December) pp. 265-375 DOI: https://doi.org/10.3807/KJOP.2024.35.6.265 Fig. 1 (a) Photograph of the tunable hemispherical electronic eye camera system. (b) Photographs of the photodiode array imaged through a lens at different magnifications (left: smaller radius of curvature, right: larger radius of curvature). (c) Image demonstration of a test pattern (left: flat detector, right: detector shape matched to the Petzval surface). (a)–(c) are reprinted from I. Jung et al. Proc. Natl. Acad. Sci. 2011; 108; 1788-1793. Copyright © 2011, National Academy of Sciences [2] . (d) Optical layout showing a monocentric imager designed with a single ball lens. (e) Photographs of the five-gore structure before mounting and curved device positioned in a hemispherical fixture. (d) and (e) are reprinted from T. Wu et al. Microsyst. Nanoeng. 2016; 2; 16019. Copyright © 2016, T. Wu et al. [3] . (f) Photograph of the phototransistor array on a planar substrate. The inset shows an exploded schematic view of a phototransistor structure. (f) is reprinted from C. Choi et al. Nat. Commun. 2017; 8; 1664. Copyright © 2017, C. Choi et al. [6] . (g) Curvature forming method using two axisymmetric models of a spherical wrapping process. (h) Photograph of a curved complementary metal oxide semiconductor (CMOS) image sensor. (g) and (h) are reprinted with permission from Guenter et al. Opt. Express 2017; 25; 13010-13023. Copyright © 2017, Optical Society of America [8]. Keywords: 생체모사형 카메라, 이미지 센서, 비전 시스템 OCIS codes: (040.1490) Cameras; (110.0110) Imaging systems; (220.0220) Optical design and fabrication 초록 지능형 로봇 시대가 도래함에 따라 이미지 센서 또는 카메라 모듈에도 각 수요처에 따른 제품군의 다양화 필요성이 대두되고 있다. 이와 동시에 초소형/저전력 구동부터 하드웨어 레벨 물체 인식까지, 기존 카메라에서 구현하기 어려운 성능에 대한 수요도 늘고 있다. 한편 인간의 눈을 비롯한 자연계 동물의 눈 구조 및 기능의 우수함과 다양성은 미래 비전 시스템 개발에 큰 영감을 준다. 특히 동물의 서식지 및 생활 환경에 적응하기 위해 생태학적으로 진화한 눈에는 기존의 카메라에서 볼 수 없던 기능이 다수 존재하기 때문에, 최근 이를 모방하기 위한 연구가 활발히 이루어지고 있다. 이러한 생체모사형 카메라의 분야는 크게 렌즈 광학계, 이미지 센서, 나노포토닉 구조, 뉴런/시냅스 모사로 나눌 수 있으며, 최근에는 이를 모두 통합하여 하나의 완성된 비전 시스템을 만들기 위한 시도가 이루어지고 있다. 본 리뷰에서는 세부기술별로 나누어 연구 동향을 살피기보다는, 기술의 발전 방향에 따른 생체모사형 카메라 연구의 흐름을 추적하고자 한다. Abstract With the advent of the intelligent robotics era, there is an increasing demand for a variety of image sensors and camera modules to meet the needs of various applications. At the same time, demand is growing for performance such as ultra-compact size, low-power operation, and hardware-level object recognition that is difficult to achieve with existing cameras. The superior structures and functionalities of natural eyes, including those of humans and other animals, provide significant inspiration for the development of next-generation artificial vision systems. In particular, the unique characteristics of animal eyes, which have evolved ecologically to adapt to specific habitats and environments, exhibit functionalities beyond those found in conventional cameras. Consequently, research aiming to mimic these natural optical systems has become very active. Bioinspired cameras can generally be categorized into lens optics, image sensors, nanophotonic structures, and neuron/synapse mimics. Recently, there have been attempts to integrate all these components into a complete vision system. This review aims to trace trends in bioinspired cameras, focusing not on the technical aspects of individual components but on overall directions in technological advancement. [하이라이트 논문] 한국광학회지 Vol. 35 No.5 (2024 Ocotber) Soliton Mode-locking and Numerical Analysis of Yb3+-doped Potassium Double Tungstate Lasers in Compact Laser Cavity Geometries Yb3+ 도핑된 칼륨 이중 텅스테이트 결정을 이용한 소형 공진기에서의 솔리톤 모드 잠금 레이저 구현 및 수치 해석 김덕우 ㆍ고광훈ㆍ이상민† 한국광학회지 Vol. 35 No.5 (2024 October) pp. 241-249 DOI: https://doi.org/10.3807/KJOP.2024.35.5.241 Fig. 1 Schematic of experimental setup. LD, polarization maintaining fiber-coupled laser diode; COL, fiber collimator (NA = 0.50); HWP, half-wave plate; Lens, pump focusing lens with a focal length of 50 mm; M 1,2 , concave mirrors with a radius of curvature of 50 mm; OC, output coupler; CM, GTI chirped mirror; C, laser crystal. Keywords: 펨토초 레이저, 모드 잠금, 이터븀 OCIS codes: (140.3580) Lasers, solid-state; (140.3615) Lasers, ytterbium; (140.4050) Mode-locked lasers; (140.7090) Ultrafast lasers; (190.5530) Pulse propagation and temporal solitons 초록 본 연구에서는 Yb3+ 이온이 도핑된 세 종류의 이중 텅스텐 결정, Yb:KGdW, Yb:KYW 및 Yb:KLuW을 사용하여 1039 nm의 중심파장 영역에서 반복율이 405 MHz인 연속파 모드 잠금된 소형 고체 레이저를 구현하였다. 모드 잠금을 위한 광스위칭 소자로 반도체 포화 흡수체 거울을 사용하였고, 모드 잠금 상태들은 세 결정 모두에서 수 시간 이상 Q-스위칭 불안정성 없이 안정적으로 동작하였다. 특히 Yb:KGdW 결정을 이용한 레이저는 최고 출력 125 mW에서 108 fs의 펄스폭을 갖는 펄스를 방출하였다. 또한 표준 분할 단계 푸리에 방법을 이용하여 공진기의 군지연 분산 및 자체 위상 변조를 고려한 Haus Master 방정식을 수치 해석으로 풀고, 그 결과를 실험결과와 비교 및 분석하였다. Abstract In this study, we demonstrate compact mode-locked laser operations using three different kinds of Yb3+-doped potassium double tungstate laser crystals, Yb:KGdW, Yb:KYW and Yb:KLuW, operating near 1040 nm at a repetition rate of 405 MHz. We utilized a semiconductor saturable absorber mirror (SESAM) as a mode locker, successfully maintaining mode-locked states for several hours without any Q-switching instabilities for all types of laser crystals. Notably, the Yb:KGdW mode-locked laser produces the shortest pulse with a duration of 108 fs, delivering 125 mW of output power. Additionally, we conducted a numerical analysis by solving the Haus Master equation, which incorporates the effect of group delay dispersion and self-phase modulation, using the standard split-step Fourier method. [Editor's Pick] Current Optics and Photonics Vol. 8 no. 5 (2024 October) Cell Death Inhibition Effect of Antioxidant Activity by 630 and 850 nm LEDs in RAW264.7 Cells Hee Eun Kim, Eun Young Kim>, Jin Chul Ahn*, and Sang Joon Mo** Current Optics and Photonics Vol. 8 No. 5 (2024 October), pp. 441-455 DOI: https://doi.org/10.3807/COPP.2024.8.5.441 Fig. 1 Photographs showing the lighting conditions during exposure of RAW264.7 cells to red (left) and near-infrared (right) LED lights. LED devices for a cell culture plate with an output irradiance of 10 mW/cm2 light at a distance of 5 cm. To cool the LED board, a cooling fan is installed to control temperature rise. Keywords: Antioxidant activity, Cell death, Light-emitting diode, RAW264.7 cell OCIS codes: (000.1430) Biology and medicine; (170.0170) Medical optics and biotechnology; (170.1420) Biology; (170.1610) Clinical applications Abstract This study objective was to evaluate the effects and mechanisms of low-level laser therapy in H2O2-induced cell death in mouse macrophage RAW264.7 cell. After irradiation with 630 and 850 nm wavelength diode lasers with an intensity of 10 mW/cm2 in RAW264.7 cells treated with 0.7 Mm H2O2, the effects and mechanisms of the two wavelengths on cell death inhibition were evaluated using MTT assay, ROS staining, TUNEL assay, flow cytometry analysis, and Western blot analysis. As a result, 630 or 850 nm light-emitting diodes (LED) were irradiated for 10 or 40 minutes to increase cell viability with H2O2 by about 1.7- or 1.6-fold, respectively. In addition, irradiation with two LEDs showed significant ROS scavenging effects, and TUNEL-positive cells were significantly reduced by 45.7% (630 nm) and 37.8% (850 nm) compared to cells treated with H2O2 alone. The Bax/Bcl-2 ratio of cells irradiated with both LEDs was significantly lower than that of cells treated with H2O2 only, and the expression of procaspase-3 and cleaved PARP was also significantly expressed in the direction of suppressing cell death. In conclusion, ROS scavenging activity by both LEDs irradiation leads to the expression of cell death pathway proteins in the direction of inhibiting cell death. [하이라이트 논문] 한국광학회지 Vol. 35 No.4 (2024 August) Hyperlens and Metalens-based Biomedical Imaging 하이퍼렌즈 및 메타렌즈 기반 바이오메디컬 이미징 박혜미1,2 *ㆍ조용재1 *ㆍ김인기1,2† 한국광학회지 Vol. 35 No.4 (2024 August) pp. 135-142 DOI: https://doi.org/10.3807/KJOP.2024.35.4.135 Fig. 1 Examples of metamaterials operating at various wavelengths. The working mechanism and operation wavelength vary depending on the materials and structures. (a) V-shaped antenna metamaterial fabricated on a silicon wafer. Reprinted with permission from N. Yu et al. Science 2011; 334; 333-337. Copyright © 2011, The American Association for the Advancement of Science [7] . (b), (c) Scanning electron microscope images of square-shaped crystalline silicon metamaterials. Reprinted with permission from H. Liang et al. Nano Lett. 2018; 18; 4460-4466. Copyright © 2018, American Chemical Society [8] . (d) Chiral metamaterial fabricated by electron beam lithography. Scale bar: 500 nm. Reprinted with permission from [9] Copyright © 2007, Optical Society of America. (e) Fishnet structure metamaterial fabricated by nanoimprint lithography. Reprinted with permission from W. Wu et al. Appl. Phys. A 2007; 87; 143-150. Copyright © 2007, Springer-Verlag [10] . (f) Scanning electron microscope images of hyperbolic metamaterials composed of silver/germanium multilayers, shown with two, three, and four pairs of layers, respectively. Reprinted with permission from X. Yang et al. Nat. Photonics 2012; 6; 450-454. Copyright © 2012, Springer Nature Limited [11] . Keywords: 바이오 메디컬 이미징, 하이퍼렌즈, 메타렌즈, 메타물질 OCIS codes: (160.3918) Metamaterials; (170.3880) Medical and biological imaging; (220.0220) Optical design and fabrication 초록 바이오 메디컬 이미징 기술은 생물학적 연구 및 의료 기술에 사용되는 이미징 기법으로서 생물학적 과정, 구조 및 상태를 탐구하는 데 필수이 며, 질병의 조기 진단과 치료법 개발에도 중요한 역할을 하고 있다. 그중에서도 특히 빛을 이용한 광학 이미징 기술은 생물학 연구에서 가장 많이 활용되고 활발하게 연구되고 있다. 광학 이미징 기술의 발전에 가장 큰 걸림돌이 되고 있는 것은 해상도 및 빛의 투과 깊이 한계 등의 문제 인데, 최근에는 메타물질을 이용하여 이를 해결하고자 하는 연구가 활발해지고 있는 추세이다. 메타물질은 나노구조체의 규칙적인 배열을 통해 빛의 성질을 자유롭게 조절하는 물질로서, 이미징 분야에서는 이미 혁신적인 도구로 자리잡고 있다. 이 글에서는 메타물질을 활용한 광학 이미징 기술의 작동 원리와 주요 응용 사례에 대해 자세히 소개하고자 한다 Abstract Biomedical imaging technologies refer to imaging techniques used in biological research and medical technology that are essential for exploring biological processes, structures, and conditions. They also play a crucial role in the early diagnosis of diseases and the development of treatments. Optical imaging technologies, in particular, are the most widely used and actively researched in biological studies. The major obstacles to technological advancement are the limitations in resolution and light penetration depth. Recently, many technologies have been studied to overcome these limitations using metamaterials. These are materials that can freely manipulate the properties of light through the regular arrangement of nanostructures and have established themselves as innovative tools in the imaging field. This article aims to provide a detailed introduction to the working principles and key applications of these technologies. [Editor's Pick] Current Optics and Photonics Vol. 8 no. 4 (2024 August) Utilizing Optical Phantoms for Biomedical-optics Technology:Recent Advances and Challenges Ik Hwan Kwon1†, Hoon-Sup Kim1†, Do Yeon Kim1,2†, Hyun-Ji Lee1,3†, and Sang-Won Lee1,3,4 * Current Optics and Photonics Vol. 8 No. 4 (2024 August), pp. 327-344 DOI: https://doi.org/10.3807/COPP.2024.8.4.327 Fig. 1 Phantoms of optical coherence tomography (OCT) for image calibration and functional quality test. (a) The OCT image and graphs of a single-layer phantom. The nano phantom consists of ultra violet (UV)-curing epoxy and nano-shells to compare the performance of the four OCT systems. Reprinted with permission from A. Fouad et al. Biomed. Opt. Express [1]. Copyright © 2014, Optica Publishing Group. (b) Schematic and OCT images of multi-layer phantoms. Reprinted with permission from A.Agrawal et al. Biomed. Opt. Express [3]. Copyright © 2013, Optica Publishing Group. (c) Wave propagation pattern of phantom from optical coherence elastography. Reprinted from S. Song et al. J. Biomed. Opt. 2013; 18; 21509. Copyright © 2013, SPIE [60]. (d) Spectroscopic OCT image and map of spectroscopic metrics of the phantom. See the main text for details. Reprinted with permission from V. Jaedicke et al. Biomed. Opt. Express [37]. Copyright © 2013, Optica Publishing Group. Keywords: Calibration, Evaluation, Optical phantom, Tissue-mimic OCIS codes: (120.4800) Optical standards and testing; (170.0110) Imaging systems; (170.0170) Medical optics and biotechnology; (170.3890) Medical optics instrumentation;(220.0220) Optical design and fabrication Abstract Optical phantoms are essential in optical imaging and measurement instruments for performance evaluation, calibration, and quality control. They enable precise measurement of image resolution, accuracy, sensitivity, and contrast, which are crucial for both research and clinical diagnostics. This paper reviews the recent advancements and challenges in phantoms for optical coherence tomography, photoacoustic imaging, digital holographic microscopy, optical diffraction tomography, and oximetry tools. We explore the fundamental principles of each technology, the key factors in phantom development, and the evaluation criteria. Additionally, we discuss the application of phantoms used for enhancing opticalimage quality. This investigation includes the development of realistic biological and clinical tissuemimicking phantoms, emphasizing their role in improving the accuracy and reliability of optical imaging and measurement instruments in biomedical and clinical research. [하이라이트 논문] 한국광학회지 Vol. 35 No.3 (2024 June) Fabrication and Optical Characterization of Highly Dy3+-ion Incorporated Alumino-borosilicate Glasses for Magneto-optical Applications at 1550 nm 1550 nm 자기광학 응용을 위한 고농도 Dy3+ 이온이 함유된 알루미노보로실리케이트 유리의 제조 및 자기광학 특성 분석 카다탈라 린가나ㆍ류용탁ㆍ박영욱ㆍ유봉안ㆍ김복현1† 한국광학회지 Vol. 35 No.3 (2024 June) pp. 115-120 DOI: https://doi.org/10.3807/KJOP.2024.35.3.115 Fig. 1 Highly Dy3+-ion incorporated alumino-borosilicate glass samples fabricated by melt quenching process using an electric furnace (glass sample size: 10 × 10 × 15 mm3). Keywords: 알루미노보로실리케이트 유리, 디스프로슘 이온(Dy3+), 광특성, 자기광학 효과, 베르데 상수 OCIS codes: (160.2750) Glass and other amorphous; (160.5690) Rare-earth-doped materials; (230.2240) Faraday effect; (210.3810) Magneto-optic systems; (160.4760) Optical properties 초록 자기광학(magneto-optical, MO) 효과가 우수한 광학소재는 자기장센서, 광전류센서, 광 고립기(optical isolator), 그리고 광서큘레이터와 같은 다양한 응용 분야에서 활용될 수 있어 많은 관심을 받고 있다. 본 연구에서는 일반적인 유리용융법을 사용하여 Dy3+ 이온이 고농도로 함유된 알루미노보로실리케이트(alumino-borosilicate, ABS) 광학유리를 제조하고, Dy3+ 이온 농도에 따른 ABS-Dy 유리의 열 특성, 광 특성 및 자기광학 특성을 분석하였으며 1550 nm 파장 대역에서 유리의 MO 특성을 패러데이 회전각 측정을 통하여 분석하였다. 패러데이 회전 각은 유리의 Dy3+ 이온 농도가 증가함에 따라 선형적으로 증가하는 것으로 나타났으며, 특히 Dy2O3 함량이 30 mol%인 유리는 −6.86 rad/ (T·m) 가량의 높은 베르데 상수를 갖는 것으로 확인되었다. 또한 제조된 ABS-Dy 유리는 128 ℃ 이상의 우수한 열안정성(∆T = Tx − Tg)과 파장 대역이 각각 490–710, 1390–1560, 1800–2400 nm일 때 70% 이상의 높은 광투과특성을 보여주었다. 이상의 높은 베르데 상수와 우수한 열안정성은 본 연구에서 제안한 ABS-Dy 유리가 1550 nm MO 소자용 광학소재로 사용 가능함을 시사한다. Abstract Magneto-optical (MO) materials have attracted much attention, since they can be utilized for various optical applications, such as magnetic field sensors, optical current sensors, optical isolators, and optical circulators. In this study, alumino-borosilicate (ABS) glasses with high concentrations of Dy3+ ions were fabricated by a conventional melt-quenching technique, and the dependence of their thermal, optical, and magneto-optical properties on Dy3+-ion concentration was investigated. The MO property of the glasses was investigated by measurement of Faraday rotation at 1550 nm. The Faraday rotation angle increased linearly with the increase of Dy3+-ion concentration in the glasses. A very high Verdet constant of −6.86 rad/(T·m) was obtained for glass with a Dy 3+ -ion concentration of 30 mol%. In addition, the ABS-Dy glasses showed good thermal stability of greater than 128 ℃ against crystallization, and high optical transmission of 70% in the visible to near-infrared windows of 480–720, 1390–1560, and 1800–2400 nm. Due to the high Verdet constant and good thermal stability, the ABS-Dy glasses in this study could be candidate optical materials for MO device applications at 1550 nm. [Editor's Pick] Current Optics and Photonics Vol. 8 no. 3 (2024 June) Fabrication of Phase Plate to Simulate Turbulence Effects on an Optical Imaging System in Strong Atmospheric Conditions Han-Gyol Oh1,2, Pilseong Kang1, Jaehyun Lee1, Hyug-Gyo Rhee1,2 *, Young-Sik Ghim1,2 **, and Jun Ho Lee3 Current Optics and Photonics Vol. 8 No. 3 (2024 June), pp. 259-269 DOI: https://doi.org/10.3807/COPP.2024.8.3.259 Fig. 1 Schematic diagram of (a) effect of turbulence layer (atmosphere) in the telescope, (b) adaptive optics (AO) system using an optical phase plate (OPP) as the turbulence layer. Keywords: Adaptive optics, Air disturbance, Fabrication, Optical phase plate OCIS codes: (010.1330) Atmospheric turbulence; (220.1080) Active or adaptive optics; (220.4610) Optical fabrication Abstract Optical imaging systems that operate through atmospheric pathways often suffer from image degradation, mainly caused by the distortion of light waves due to turbulence in the atmosphere. Adaptive optics technology can be used to correct the image distortion caused by atmospheric disturbances. However, there are challenges in conducting experiments with strong atmospheric conditions. An optical phase plate (OPP) is a device that can simulate real atmospheric conditions in a lab setting. We suggest a novel two-step process to fabricate an OPP capable of simulating the effects of atmospheric turbulence. The proposed fabrication method simplifies the process by eliminating additional activities such as phase-screen design and phase simulation. This enables an efficient and economical fabrication of the OPP. We conducted our analysis using the statistical fluctuations of the refractive index and applied modal expansion using Kolmogorov’s theory. The experiment aims to fabricate an OPP with parameters D/r0 ≈ 30 and r0 ≈ 5 cm. The objective is defined with the strong atmospheric conditions. Finally, we have fabricated an OPP that satisfied the desired objectives. The OPP closely simulate turbulence to real atmospheric conditions. [Editor's Pick] Current Optics and Photonics Vol. 8 no. 2 (2024 April) Quantifying Aberrations on Object Plane Using Zernike Polynomials Yohan Kim1 *, Theo Nam Sohn2, Cheong Soo Seo1, and Jin Young Sohn1 Current Optics and Photonics Vol. 8 No. 2 (2024 April), pp. 151-155 DOI: https://doi.org/10.3807/COPP.2024.8.2.151 Fig. 1 Optical layout of 1.5× magnification WiseScope. LED, light-emitting diode; PBS, polarizing beam splitter. Keywords: Focus measure, Optical aberration, Wavefront error, Zernike polynomials OCIS codes: (010.7350) Wave-front sensing; (080.1010) Aberrations (global); (100.2550) Focalplane-array image processors; (110.0110) Imaging systems; (120.4640) Optical instruments Abstract Optical systems often suffer from optical aberrations caused by imperfect hardware, which places significant constraints on their utility and performance. To reduce these undesirable effects, a comprehensive understanding of the aberrations inherent to optical systems is needed. This article presents an effective method for aberration detection using Zernike polynomials. The process involves scanning the object plane to identify the optimal focus and subsequently fitting the acquired focus data to Zernike polynomials. This fitting procedure facilitates the analysis of various aberrations in the optical system.
