[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. [하이라이트 논문] 한국광학회지 Vol. 35 No.2 (2024 April) 12개 다이오드 레이저를 활용하는 레이저 복사출력계 교정시스템 개발 Development of Laser Power Meter Calibration System with 12-diode Laser Sources 이강희ㆍ유재근ㆍ배인호ㆍ박성종ㆍ이동훈1† 한국광학회지 Vol. 35 No.2 (2024 April) pp. 61-70 DOI: https://doi.org/10.3807/KJOP.2024.35.2.061 Fig. 1 Schematics and photographs of the laser power calibration system. Commercially available fiber-coupled laser diodes (Thorlabs,) are used, and the model names of the lasers are listed below their wavelengths. Three laser power controllers (LPC; BEOC) are additionally used for laser power stabilization. The system is designed to automatically select the laser for the calibration process using multiple motorized translation stages. In the schematics, DUT denotes device under test, while Ref denotes reference for the calibration. Keywords: 검출기 기반 복사 측정, 레이저 복사출력계 교정, 적분구 OCIS codes: (120.3150) Integrating spheres; (120.5630) Radiometry; (140.2020) Diode lasers; (230.5170) Photodiodes 초록 400 nm부터 1,600 nm까지의 파장 영역에서 단일 모드 광섬유에 결합된 12개의 다이오드 레이저 광원를 기반으로 하는 레이저 복사출력계 교정시스템을 소개한다. 본 시스템은 복사출력 측정위치에서 레이저 출력요동을 최소화하였고 모든 광원에 대해 비슷한 빔크기를 갖는다. 또한 감응도의 비균일도 및 비선형성을 최소화하기 위해 적분구 기준기를 사용하였다. 이 교정시스템의 최소 측정불확도는 대부분의 레이저 파장에서 1.1% (k = 2)로 추정된다. Abstract We demonstrate a laser power meter calibration system based on 12-diode laser sources coupled to single-mode fibres in a wavelength range from 400 to 1,600 nm. In our system, three laser power controllers ensure that the output power uncertainty of all laser sources is less than 0.1% (k = 2). In addition, all laser beams are adjusted to have similar beam sizes of approximately 2 mm (1/e 2 -width) at the measurement position to minimise unmeasured laser power on a detector. As a reference detector, we use an integrating sphere combined with silicon and indium gallium arsenide photodiodes to minimise the non-uniformity and non-linearity of responsivity. The minimum uncertainty of the calibration system is estimated to be 1.1% (k = 2) for most laser wavelengths. [Editor's Pick] Current Optics and Photonics Vol. 8 no. 1 (2024 February) SLODAR System Development for Vertical Atmospheric Disturbance Profiling at Geochang Observatory Ji Yong Joo1, Hyeon Seung Ha1, Jun Ho Lee1,2 *, Do Hwan Jung1,3, Young Soo Kim1,3, and Timothy Butterley4 Current Optics and Photonics Vol. 8 No. 1 (2024 February) pp. 30-37 DOI: https://doi.org/10.3807/COPP.2024.8.1.30 Fig. 1 Schematic diagram illustrating the crossed-beam method. This specific diagram depicts the construction of 8 layers of vertical profiling with 8 sub-aperture wavefront sensing [13]. Keywords: Adaptive optics, Atmospheric turbulence, Fried parameter, Refractive index structure function (C2n), SLODAR OCIS codes: (010.1330) Atmospheric turbulence; (120.4640) Optical instruments; (220.1080) Active or adaptive optics; (350.1260) Astronomical optics Abstract Implemented at the Geochang Observatory in South Korea, our slope detection and ranging (SLODAR) system features a 508 mm Cassegrain telescope (f /7.8), incorporating two Shack-Hartmann wave-front sensors (WFS) for precise measurements of atmospheric phase distortions, particularly from nearby binary or double stars, utilizing an 8 × 8 grid of sampling points. With an ability to reconstruct eight-layer vertical atmospheric profiles, the system quantifies the refractive index structure function (C2n) through the crossed-beam method. Adaptable in vertical profiling altitude, ranging from a few hundred meters to several kilometers, contingent on the separation angle of binary stars, the system operates in both wide (2.5 to 12.5 arcminute separation angle) and narrow modes (11 to 15 arcsecond separation angle), covering altitudes from 122.3 to 611.5 meters and 6.1 to 8.3 kilometers, respectively. Initial measurements at the Geochang Observatory indicated C values up to 181.7 meters with a Fried parameter (r0) of 8.4 centimeters in wide mode and up to 7.8 kilometers with an r0 of 8.0 centimeters in narrow mode, suggesting similar seeing conditions to the Bohyun Observatory and aligning with a comparable 2014–2015 seeing profiling campaign in South Korea. [하이라이트 논문] 한국광학회지 Vol. 35 No.1 (2024 February) 나노구조 기반 초박형 적외선 차단 필터 An Ultra-thin IR Cut-off Filter Based on Nanostructures 양현도ㆍ이종권1† 한국광학회지 Vol. 35 No.1 (2024 February) pp. 24-29 DOI: https://doi.org/10.3807/KJOP.2024.35.1.024 Fig. 1 (a) Ellipsoidal and hyperboloidal dispersion relations and (b) schematic of a layered metal-dielectric metastructure with the permittivities of the two constituents given as em and ed . Keywords: 적외선 차단 필터, 나노 패턴, 쌍곡선 메타구조, 초박형 OCIS codes: (120.2440) Filters; (130.1750) Components; (130.3130) Integrated optics materials; (310.6628) Subwavelength structures, nano structures 초록 본 연구에서는 나노패턴된 금속(Ag)-유전체(PDMS) 다층 기반의 쌍곡선 메타구조를 제안하고 영상 소자용 적외선 차단 필터의 성능에 대해 보고한다. 사각형 모양의 Ag 나노 패턴의 크기와 Ag 나노 패턴을 둘러싼 PDMS의 두께를 최적화함으로써, 제안된 IR 차단 필터가 0.70–1.01μm 파장 대역의 빛을 99% 차단하면서도 가시광 영역에서 94% 이상의 높은 투과율을 나타냄을 보였다. 차단 파장 대역은 쌍곡선 메타구조의 epsilon-near-zero 파장보다 긴 파장 영역에서 시작하여 Ag 나노 패턴에 의한 플라즈모닉 흡수가 강한 지점에서 끝나게 된다. 근적외선 차단 대역보다 긴 파장 영역에서는 수평으로 인접한 Ag 나노패턴들 사이의 플라즈모닉 커플링 효과로 다시 투과도가 증가됨을 알 수 있다. 이러한 메타구조체는 적외선 차단 필터의 성능을 향상시킬 수 있을 뿐만 아니라 공정 단순화를 통해 초박형 제조가 가능하여, 다양한 평면 광학 및 집적광학 부품들에 적용될 수 있다. Abstract We propose a hyperbolic metastructure based on a nanopatterned metal (Ag)-dielectric (PDMS) multilayer and report on its performance in an infrared (IR) cut-off filter for imaging devices. By optimizing the size of the square-shaped Ag nanopattern and the thickness of PDMS surrounding the Ag nanopattern, the proposed IR cut-off filter blocks 99% of light in the 0.70–1.01 μm wavelength band while maintaining a high transmittance of over 94% in the visible region. Here, the cut-off wavelength band starts at a region above the epsilon-near-zero wavelength of the hyperbolic metastructure and ends at the point where plasmonic absorption appears strongly. It is observed that transmittance in the wavelength region longer than the IR cut-off band increases again due to plasmonic coupling among horizontally adjacent Ag nanopatterns. This metastructure can improve the performance of IR-locking filters as well as allow it to be manufactured ultra-thin, which is applicable to various planar optical elements and integrated optical components. [Editor's Pick] Current Optics and Photonics Vol. 7 no. 6 (2023 December) Femtosecond Mid-IR Cr:ZnS Laser with Transmitting Graphene-ZnSe Saturable Absorber Won Bae Cho1 *, Ji Eun Bae2, Seong Cheol Lee2, No Soung Myoung3, and Fabian Rotermund2 Current Optics and Photonics Vol. 7 No. 6 (2023 December) pp. 738-744 DOI: https://doi.org/10.3807/COPP.2023.7.6.738 Fig. 1 Optical transmission of high-quality monolayer graphene saturable absorber (G-SA) and photos of the G-SAs developed on CaF2 and ZnSe substrate (inset). (a) Graphene transferred onto CaF2 substrate. (b) Graphene transferred onto ZnSe substrate. Keywords: Cr:ZnS, Graphene-ZnSe, Mid-infrared laser, Passive mode-locking, Saturable absorber OCIS codes: (140.4050) Mode-locked lasers; (140.7090) Ultrafast lasers; (160.4236) Nanomaterials; (160.4330) Nonlinear optical materials Abstract Graphene-based saturable absorbers (SAs) are widely used as laser mode-lockers at various laser oscillators. In particular, transmission-type graphene-SAs with ultrabroad spectral coverage are typically manufactured on transparent substrates with low nonlinearity to minimize the effects on the oscillators. Here, we developed two types of transmitting graphene SAs based on CaF2 and ZnSe. Using the graphene-SA based on CaF2, a passively mode-locked mid-infrared Cr:ZnS laser delivers relatively long 540 fs pulses with a maximum output power of up to 760 mW. In the negative net cavity dispersion regime, the pulse width was not reduced further by inhomogeneous group delay dispersion (GDD) compensation. In the same laser cavity, we replaced only the graphene-SA based on CaF2 with the SA based on ZnSe. Due to the additional self-phase modulation effect induced by the ZnSe substrate with high nonlinearity, the stably mode-locked Cr:ZnS laser produced Fourier transform-limited ~130 fs near 2,340 nm. In the stable single-pulse operation regime, average output powers up to 635 mW at 234 MHz repetition rates were achieved. To our knowledge, this is the first attempt to achieve shorter pulse widths from a polycrystalline Cr:ZnS laser by utilizing the graphene deposited on the substrate with high nonlinearity. [하이라이트 논문] 한국광학회지 Vol. 34 No.6 (2023 December) 반사형 Focal Reducer를 가지는 높은 개구수의 대물렌즈 설계 Optical Design of a High-numerical-aperture Objective with a Reflective Focal Reducer 이종웅1† 한국광학회지 Vol. 34 No.6 (2023 December) pp. 248-260 DOI: https://doi.org/10.3807/KJOP.2023.34.6.248 Fig. 1 Optical layout of a two-spherical mirror system. Keywords: 아나스티그마트, 고해상 대물렌즈, 반사형 포컬 리듀서, 2구면경계 OCIS codes: (080.4035) Mirror system design; (110.0180) Microscopy; (220.1000) Aberration compensation; (220.3620) Lens system design 초록 낮은 NA의 굴절형 대물렌즈와 반사형 focal reducer로 구성된 NA 0.5의 굴절-반사 대물렌즈를 설계하였다. 굴절형 대물렌즈로는 NA 0.25 인 Lister 대물렌즈가 사용되고, 반사형 focal reducer는 구면수차, 코마, 비점수차가 보정된 2구면경계가 사용되었다. 설계된 굴절-반사 대물렌즈는 높은 NA를 가졌음에도 18 mm의 긴 작동거리와 NA 0.25의 Lister 대물렌즈보다 개선된 결상성능을 가지고 있다. Abstract A 0.5-NA refractive-reflective objective, composed of a low-NA refractive and a reflective focal reducer, is designed. A 0.25-NA Lister objective is used for the refractive. A two-spherical-mirror system, corrected for spherical aberration, coma, and astigmatism is used for the reflective focal reducer. In spite of high NA, the refractive-reflective objective has an 18-mm working distance and improved imaging performance, compared to the 0.25-NA Lister objective. 12345
[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. [하이라이트 논문] 한국광학회지 Vol. 35 No.2 (2024 April) 12개 다이오드 레이저를 활용하는 레이저 복사출력계 교정시스템 개발 Development of Laser Power Meter Calibration System with 12-diode Laser Sources 이강희ㆍ유재근ㆍ배인호ㆍ박성종ㆍ이동훈1† 한국광학회지 Vol. 35 No.2 (2024 April) pp. 61-70 DOI: https://doi.org/10.3807/KJOP.2024.35.2.061 Fig. 1 Schematics and photographs of the laser power calibration system. Commercially available fiber-coupled laser diodes (Thorlabs,) are used, and the model names of the lasers are listed below their wavelengths. Three laser power controllers (LPC; BEOC) are additionally used for laser power stabilization. The system is designed to automatically select the laser for the calibration process using multiple motorized translation stages. In the schematics, DUT denotes device under test, while Ref denotes reference for the calibration. Keywords: 검출기 기반 복사 측정, 레이저 복사출력계 교정, 적분구 OCIS codes: (120.3150) Integrating spheres; (120.5630) Radiometry; (140.2020) Diode lasers; (230.5170) Photodiodes 초록 400 nm부터 1,600 nm까지의 파장 영역에서 단일 모드 광섬유에 결합된 12개의 다이오드 레이저 광원를 기반으로 하는 레이저 복사출력계 교정시스템을 소개한다. 본 시스템은 복사출력 측정위치에서 레이저 출력요동을 최소화하였고 모든 광원에 대해 비슷한 빔크기를 갖는다. 또한 감응도의 비균일도 및 비선형성을 최소화하기 위해 적분구 기준기를 사용하였다. 이 교정시스템의 최소 측정불확도는 대부분의 레이저 파장에서 1.1% (k = 2)로 추정된다. Abstract We demonstrate a laser power meter calibration system based on 12-diode laser sources coupled to single-mode fibres in a wavelength range from 400 to 1,600 nm. In our system, three laser power controllers ensure that the output power uncertainty of all laser sources is less than 0.1% (k = 2). In addition, all laser beams are adjusted to have similar beam sizes of approximately 2 mm (1/e 2 -width) at the measurement position to minimise unmeasured laser power on a detector. As a reference detector, we use an integrating sphere combined with silicon and indium gallium arsenide photodiodes to minimise the non-uniformity and non-linearity of responsivity. The minimum uncertainty of the calibration system is estimated to be 1.1% (k = 2) for most laser wavelengths. [Editor's Pick] Current Optics and Photonics Vol. 8 no. 1 (2024 February) SLODAR System Development for Vertical Atmospheric Disturbance Profiling at Geochang Observatory Ji Yong Joo1, Hyeon Seung Ha1, Jun Ho Lee1,2 *, Do Hwan Jung1,3, Young Soo Kim1,3, and Timothy Butterley4 Current Optics and Photonics Vol. 8 No. 1 (2024 February) pp. 30-37 DOI: https://doi.org/10.3807/COPP.2024.8.1.30 Fig. 1 Schematic diagram illustrating the crossed-beam method. This specific diagram depicts the construction of 8 layers of vertical profiling with 8 sub-aperture wavefront sensing [13]. Keywords: Adaptive optics, Atmospheric turbulence, Fried parameter, Refractive index structure function (C2n), SLODAR OCIS codes: (010.1330) Atmospheric turbulence; (120.4640) Optical instruments; (220.1080) Active or adaptive optics; (350.1260) Astronomical optics Abstract Implemented at the Geochang Observatory in South Korea, our slope detection and ranging (SLODAR) system features a 508 mm Cassegrain telescope (f /7.8), incorporating two Shack-Hartmann wave-front sensors (WFS) for precise measurements of atmospheric phase distortions, particularly from nearby binary or double stars, utilizing an 8 × 8 grid of sampling points. With an ability to reconstruct eight-layer vertical atmospheric profiles, the system quantifies the refractive index structure function (C2n) through the crossed-beam method. Adaptable in vertical profiling altitude, ranging from a few hundred meters to several kilometers, contingent on the separation angle of binary stars, the system operates in both wide (2.5 to 12.5 arcminute separation angle) and narrow modes (11 to 15 arcsecond separation angle), covering altitudes from 122.3 to 611.5 meters and 6.1 to 8.3 kilometers, respectively. Initial measurements at the Geochang Observatory indicated C values up to 181.7 meters with a Fried parameter (r0) of 8.4 centimeters in wide mode and up to 7.8 kilometers with an r0 of 8.0 centimeters in narrow mode, suggesting similar seeing conditions to the Bohyun Observatory and aligning with a comparable 2014–2015 seeing profiling campaign in South Korea. [하이라이트 논문] 한국광학회지 Vol. 35 No.1 (2024 February) 나노구조 기반 초박형 적외선 차단 필터 An Ultra-thin IR Cut-off Filter Based on Nanostructures 양현도ㆍ이종권1† 한국광학회지 Vol. 35 No.1 (2024 February) pp. 24-29 DOI: https://doi.org/10.3807/KJOP.2024.35.1.024 Fig. 1 (a) Ellipsoidal and hyperboloidal dispersion relations and (b) schematic of a layered metal-dielectric metastructure with the permittivities of the two constituents given as em and ed . Keywords: 적외선 차단 필터, 나노 패턴, 쌍곡선 메타구조, 초박형 OCIS codes: (120.2440) Filters; (130.1750) Components; (130.3130) Integrated optics materials; (310.6628) Subwavelength structures, nano structures 초록 본 연구에서는 나노패턴된 금속(Ag)-유전체(PDMS) 다층 기반의 쌍곡선 메타구조를 제안하고 영상 소자용 적외선 차단 필터의 성능에 대해 보고한다. 사각형 모양의 Ag 나노 패턴의 크기와 Ag 나노 패턴을 둘러싼 PDMS의 두께를 최적화함으로써, 제안된 IR 차단 필터가 0.70–1.01μm 파장 대역의 빛을 99% 차단하면서도 가시광 영역에서 94% 이상의 높은 투과율을 나타냄을 보였다. 차단 파장 대역은 쌍곡선 메타구조의 epsilon-near-zero 파장보다 긴 파장 영역에서 시작하여 Ag 나노 패턴에 의한 플라즈모닉 흡수가 강한 지점에서 끝나게 된다. 근적외선 차단 대역보다 긴 파장 영역에서는 수평으로 인접한 Ag 나노패턴들 사이의 플라즈모닉 커플링 효과로 다시 투과도가 증가됨을 알 수 있다. 이러한 메타구조체는 적외선 차단 필터의 성능을 향상시킬 수 있을 뿐만 아니라 공정 단순화를 통해 초박형 제조가 가능하여, 다양한 평면 광학 및 집적광학 부품들에 적용될 수 있다. Abstract We propose a hyperbolic metastructure based on a nanopatterned metal (Ag)-dielectric (PDMS) multilayer and report on its performance in an infrared (IR) cut-off filter for imaging devices. By optimizing the size of the square-shaped Ag nanopattern and the thickness of PDMS surrounding the Ag nanopattern, the proposed IR cut-off filter blocks 99% of light in the 0.70–1.01 μm wavelength band while maintaining a high transmittance of over 94% in the visible region. Here, the cut-off wavelength band starts at a region above the epsilon-near-zero wavelength of the hyperbolic metastructure and ends at the point where plasmonic absorption appears strongly. It is observed that transmittance in the wavelength region longer than the IR cut-off band increases again due to plasmonic coupling among horizontally adjacent Ag nanopatterns. This metastructure can improve the performance of IR-locking filters as well as allow it to be manufactured ultra-thin, which is applicable to various planar optical elements and integrated optical components. [Editor's Pick] Current Optics and Photonics Vol. 7 no. 6 (2023 December) Femtosecond Mid-IR Cr:ZnS Laser with Transmitting Graphene-ZnSe Saturable Absorber Won Bae Cho1 *, Ji Eun Bae2, Seong Cheol Lee2, No Soung Myoung3, and Fabian Rotermund2 Current Optics and Photonics Vol. 7 No. 6 (2023 December) pp. 738-744 DOI: https://doi.org/10.3807/COPP.2023.7.6.738 Fig. 1 Optical transmission of high-quality monolayer graphene saturable absorber (G-SA) and photos of the G-SAs developed on CaF2 and ZnSe substrate (inset). (a) Graphene transferred onto CaF2 substrate. (b) Graphene transferred onto ZnSe substrate. Keywords: Cr:ZnS, Graphene-ZnSe, Mid-infrared laser, Passive mode-locking, Saturable absorber OCIS codes: (140.4050) Mode-locked lasers; (140.7090) Ultrafast lasers; (160.4236) Nanomaterials; (160.4330) Nonlinear optical materials Abstract Graphene-based saturable absorbers (SAs) are widely used as laser mode-lockers at various laser oscillators. In particular, transmission-type graphene-SAs with ultrabroad spectral coverage are typically manufactured on transparent substrates with low nonlinearity to minimize the effects on the oscillators. Here, we developed two types of transmitting graphene SAs based on CaF2 and ZnSe. Using the graphene-SA based on CaF2, a passively mode-locked mid-infrared Cr:ZnS laser delivers relatively long 540 fs pulses with a maximum output power of up to 760 mW. In the negative net cavity dispersion regime, the pulse width was not reduced further by inhomogeneous group delay dispersion (GDD) compensation. In the same laser cavity, we replaced only the graphene-SA based on CaF2 with the SA based on ZnSe. Due to the additional self-phase modulation effect induced by the ZnSe substrate with high nonlinearity, the stably mode-locked Cr:ZnS laser produced Fourier transform-limited ~130 fs near 2,340 nm. In the stable single-pulse operation regime, average output powers up to 635 mW at 234 MHz repetition rates were achieved. To our knowledge, this is the first attempt to achieve shorter pulse widths from a polycrystalline Cr:ZnS laser by utilizing the graphene deposited on the substrate with high nonlinearity. [하이라이트 논문] 한국광학회지 Vol. 34 No.6 (2023 December) 반사형 Focal Reducer를 가지는 높은 개구수의 대물렌즈 설계 Optical Design of a High-numerical-aperture Objective with a Reflective Focal Reducer 이종웅1† 한국광학회지 Vol. 34 No.6 (2023 December) pp. 248-260 DOI: https://doi.org/10.3807/KJOP.2023.34.6.248 Fig. 1 Optical layout of a two-spherical mirror system. Keywords: 아나스티그마트, 고해상 대물렌즈, 반사형 포컬 리듀서, 2구면경계 OCIS codes: (080.4035) Mirror system design; (110.0180) Microscopy; (220.1000) Aberration compensation; (220.3620) Lens system design 초록 낮은 NA의 굴절형 대물렌즈와 반사형 focal reducer로 구성된 NA 0.5의 굴절-반사 대물렌즈를 설계하였다. 굴절형 대물렌즈로는 NA 0.25 인 Lister 대물렌즈가 사용되고, 반사형 focal reducer는 구면수차, 코마, 비점수차가 보정된 2구면경계가 사용되었다. 설계된 굴절-반사 대물렌즈는 높은 NA를 가졌음에도 18 mm의 긴 작동거리와 NA 0.25의 Lister 대물렌즈보다 개선된 결상성능을 가지고 있다. Abstract A 0.5-NA refractive-reflective objective, composed of a low-NA refractive and a reflective focal reducer, is designed. A 0.25-NA Lister objective is used for the refractive. A two-spherical-mirror system, corrected for spherical aberration, coma, and astigmatism is used for the reflective focal reducer. In spite of high NA, the refractive-reflective objective has an 18-mm working distance and improved imaging performance, compared to the 0.25-NA Lister objective.
