https://scholar.dgist.ac.kr/handle/20.500.11750/11777 2026-04-04T12:50:03Z https://scholar.dgist.ac.kr/handle/20.500.11750/58572 Title: MEMS Actuators for Tunable Waveguide Devices in Photonic Integrated Circuits: A Brief Review Author(s): Choi, Dongju; Park, Young Jae; Her, Man Jae; Han, Sangyoon Abstract: Microelectromechanical systems (MEMS)-based tuning methods offer promising solutions for dynamically controlling optical properties in photonic integrated circuits (PICs) to address the limitations associated with traditional approaches that rely on direct modulation of the material’s refractive index. Conventional methods such as thermo-optic, plasma dispersion, and electro-optic modulation, face significant challenges including high energy consumption, limited refractive index change, and issues with heat dissipation and optical losses. By contrast, MEMS-based actuators directly reposition optical components, enabling reduced device footprints, negligible static power consumption, rapid response times, and improved reliability. This paper systematically explores the operating principles and design characteristics of five representative MEMS actuator technologies widely used in tunable waveguide devices: In-plane comb-drive actuators, cantilever actuators, gap-reducing actuators, vertical digital actuators, and vertical comb-drive actuators. Each actuator type is analyzed for its distinct advantages and challenges, with considerations such as device compactness, switching speed, voltage requirements, and robustness against reliability issues such as pull-in phenomena and stiction. The insights presented emphasize the substantial potential of MEMS-based tuning methods to advance the scalability, energy efficiency, and performance of next-generation PICs. Continued research into improving actuator performance, including increased operation speed, lower operating voltages, and further miniaturization, will be critical to achieving widespread integration and adoption. 2025-05-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/58241 Title: MEMS 기반 필드 프로그래머블 포토닉 게이트 어레이(FPPGA)의 파라미터 최적화를 위한 시뮬레이션 도구 개발 Author(s): 엄석찬; 오상열; 전영훈; 권혁수; 한상윤; 배영석 Abstract: 필드 프로그래머블 포토닉 게이트 어레이(FPPGA)는 광 회로를 사용자의 목적에 맞게 동적으로 재구성할 수있어, 통신 네트워크, 양자 컴퓨팅, RF 신호 처리 등 다양한 응용 분야에서 활용될 수 있다. 그러나 이러한 다양한 응용에 적용 가능한 프로그래머블 광 회로를 구현하기 위해서는 입출력 단자와 게이트의 수가 증가하게 되고, 그에 따라제어 파라미터의 수도 늘어나게 되다. 그리고, 이와 같은 복잡한 광학 시스템에서 원하는 기능을 구현하기 위한 최적의파라미터를 찾는 것은 어려운 과제이다. 본 연구에서는 MEMS 기반으로 구현 된 FPPGA 를 효과적으로 활용하기 위하여, 해당 구조를 기반으로 역전파 기법을 적용한 파라미터 최적화 시뮬레이션 도구를 개발하였다. 이 시뮬레이션 도구는제작된 FPPGA의 게이트 구조와 1:1로 매핑되어, 사용자의 목적에 맞게 광 회로의 파라미터를 효율적으로 설정할 수있다. 이를 통해 광 신호 라우팅, 주파수 분할 다중화, 신경망 기반 숫자 인식 등 다양한 응용에서 효과적인 파라미터최적화가 가능함을 입증하였다. 본 연구를 통해 우리는 FPPGA의 실용성을 높이고, 전문 지식이 없는 사용자도 효과적으로 활용할 수 있는 FPPGA용 인터프리터 제작의 기반을 마련하였다. Field Programmable Photonic Gate Arrays (FPPGA) can be dynamically reconfigured to meet user objectives, enabling their application in various fields such as communication networks, quantum computing, and RF signal processing. However, implementing programmable optical circuits suitable for such diverse applications requires increasing the number of input/output terminals and gates, which consequently increases the number of control parameters. As a result, finding the optimal parameters to realize desired functionalities in these complex optical systems becomes a challenging task. In this paper, to utilize MEMS-based FPPGA more effectively, we developed a parameter optimization simulation tool that applies backpropagation techniques to their architecture. This simulation tool directly maps onto the gate structure of the fabricated FPPGA, allowing efficient configuration of optical circuit parameters in alignment with user objectives. We demonstrated that effective parameter optimization is achievable in various applications, including optical signal routing, frequency division multiplexing, and neural network-based digit recognition. Our research enhances the practicality of FPPGAs and lays the groundwork for developing an FPPGA interpreter that can be effectively used by users without specialized knowledge. 2025-01-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/57683 Title: Vialess heterogeneous skin patch for multimodal monitoring and stimulation Author(s): Lee, Hyeokjun; Song, Soojeong; Yea, Junwoo; Ha, Jeongdae; Oh, Saehyuck; Jekal, Janghwan; Hong, Myung Seok; Won, Chihyeong; Jung, Han Hee; Keum, Hohyun; Han, Sangyoon; Cho, Jeong Ho; Lee, Taeyoon; Jang, Kyung-In Abstract: System-level wearable electronics require to be flexible to ensure conformal contact with the skin, but they also need to integrate rigid and bulky functional components to achieve system-level functionality. As one of integration methods, folding integration offers simplified processing and enhanced functionality through rigid-soft region separation, but so far, it has mainly been applied to modality of electrical sensing and stimulation. This paper introduces a vialess heterogeneous skin patch with multi modalities that separates the soft region and strain-robust region through folded structure. Our system includes electrical and optical modalities for hemodynamic and cardiovascular monitoring, and a force-electrically driven micropump for drug delivery. Each modality is demonstrated through on-demand drug delivery, flexible waveguide-based PPG monitoring, and ECG and body movement monitoring. Wireless data transmission and real-time measurement validate the feedback operation for multi-modalities. This engineered closed-loop platform offers the possibility for broad applications, including cardiovascular monitoring and chronic disease management. 2024-12-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/57436 Title: Fully tunable Fabry-Pérot cavity based on MEMS Sagnac loop reflector with ultra-low static power consumption Author(s): Park, Young Jae; Her, Man Jae; Jeong, Youngjae; Choi, Dong Ju; Kim, Dong Uk; Lim, Min Gi; Hong, Myung Seok; Kwon, Hyug Su; Yu, Kyoungsik; Han, Sangyoon Abstract: The Fabry-Pérot interferometer, a fundamental component in optoelectronic systems, offers interesting applications such as sensors, lasers, and filters. In this work, we show a tunable Fabry-Pérot cavity consisting of tunable Sagnac loop reflectors (SLRs) and phase shifters based on electrostatic microelectromechanical (MEMS) actuator. The fabrication process of the device is compatible with the standard wafer-level silicon photonics fabrication processes. This electrostatic actuation mechanism provides well-balanced, scalable pathways for efficient tuning methodologies. The extinction ratio of the continuously tunable SLRs’ reflectivity is larger than 20 dB. Full 2π phase shifting is achieved, and response times of all the components are less than 25 μs. Both actuators have extremely low static power, measuring under 20 fW and the energy needed for tuning is both below 20 pJ. (Figure presented.) © The Author(s) 2024. 2024-07-31T15:00:00Z