https://scholar.dgist.ac.kr/handle/20.500.11750/11776 2026-10-27T12:52:46Z https://scholar.dgist.ac.kr/handle/20.500.11750/61004 Title: Dual-directional interferometric control for post-fabrication wavelength alignment in a silicon photonic bidirectional arrayed waveguide grating Author(s): Vatandoust, Leila; Kim, Jae Hyeon; Gupta, Shashank; Kim, Taeyeon; Tusher, Munirul; Moon, Hyung-Myung; Han, Sangyoon; Merklein, Moritz; Quack, Niels Abstract: Precise wavelength alignment is essential for dense wavelength-division multiplexing (DWDM) systems, where fabrication-induced deviations can lead to channel mismatch and degraded performance. Arrayed waveguide gratings (AWGs) are widely used in silicon photonics DWDM systems; however, their passive nature limits post-fabrication spectral correction, while conventional thermo-optic tuning predominantly produces unidirectional wavelength shifts. Here, we demonstrate a dual-arm interferometric approach for post-fabrication wavelength alignment using a silicon photonic asymmetric Mach-Zehnder interferometer (AMZI)-bidirectional arrayed integrated into both AMZI arms enable dual-directional interferometric control through selective actuation of the long or short interferometer arm. In the fabricated device, an initial wavelength offset of approximately +0.17 nm from the design wavelength of 1527.99 nm is observed. At 1.8 V (29 mW), thermo-optic actuation improves the spectral overlap between the AMZI transfer function and the BiAWG passbands, resulting in a cascaded peak-transmission enhancement of approximately 3-4 dB. Under short-arm actuation at 2.1 V, the measured peak associated with the nominal central channel is observed at 1527.98 nm, bringing the measured wavelength into agreement with the design wavelength of 1527.99 nm within the experimental wavelengthsampling resolution (0.01 nm). The demonstrated dual-directional interferometric control provides a compact post-fabrication calibration approach for compensating fabrication-induced wavelength offsets while enhancing the cascaded transmission through improved spectral overlap between the AMZI transfer function and the BiAWG passbands. 2026-08-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/60980 Title: Silicon photonic MEMS platform-based air-coupled optomechanical ultrasound receiver at 2.8 MHz with an ultra-compact active acoustic sensing area Author(s): Nam, Sangwoo; Kim, Jae Hyeon; Park, Young Jae; Choi, Dongju; Kim, Dong Uk; Guezzi, Nizar; Lee, Sangheon; Seo, Youngho; Choi, Suyoung; Kim, Myeongchan; Seong, Hyojin; Lee, Changho; Ahn, Changmin; Kim, Jungwon; Yu, Jaesok; Han, Sangyoon Abstract: High-resolution non-contact non-destructive evaluation (NDE) utilizing MHz-range ultrasound in air-coupled environments faces two significant challenges: severe signal attenuation and reduced sensitivity due to transducer miniaturization. Optical ultrasound sensors have emerged as promising candidates to overcome these limitations; however, widespread adoption remains challenging. Conventional discrete optical sensors are limited by complex fabrication and rigid form factors. Furthermore, the efforts to implement these on photonic integrated circuits (PICs)-while addressing scalability-are typically constrained by limited sensitivity. To address these requirements, we report a chip-scale optomechanical ultrasound receiver implemented, for the first time, on a silicon photonics MEMS platform. This platform facilitates CMOS-compatible scalability and design freedom to independently optimize mechanical components and optical sensitivity. Consequently, the receiver demonstrates a compact active acoustic sensing area of 4 & times; 10-4 mm2. Despite this size reduction, in the noise-equivalent pressure (NEP)-active-area comparison, the proposed receiver's measured and estimated NEP values are positioned within a range comparable to or lower than those for previously reported air-coupled optical and CMUT sensors, when interpreted relative to the ideal area-scaling trend. Designed for a 2.8 MHz mechanical resonance, the receiver was benchmarked against a commercial 1 MHz air-coupled PZT transducer to provide a practical, controlled experimental baseline. In this controlled experimental comparison, the receiver showed a more than 25,000-fold higher received response per unit active acoustic area than the PZT baseline, serving as a complementary metric for unit-area received response and structural scaling potential. These findings suggest that the silicon photonic MEMS platform can provide a route toward compact, dense-array-compatible optical ultrasound receivers for localized air-coupled sensing. (c) 2026 Chinese Laser Press 2026-08-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/60564 Title: 민감도 및 동적 영역이 조절 가능한 광기계 초음파 센서 및 그 제어 방법 Author(s): 남상우; 유재석; 한상윤; 최동주 Abstract: 본 개시는 초음파 센서 및 그 동작 방법에 관한 것으로서, 더욱 상세하게는 캔틸레버 구조의 멤브레인의 초기 위치를 조절하여 민감도 및 동적 영역이 조절 가능한 광기계 초음파 센서 및 그 제어 방법에 관한 것이다. https://scholar.dgist.ac.kr/handle/20.500.11750/60560 Title: 멀티캐스트 스위치 어레이 및 이를 이용한 빔 조향 장치 Author(s): 유경식; 한상윤 Abstract: A multicast switch array and a multi-beam steering device using the same are provided. Accordingly, it is possible to precisely steer a large-scale multi-beam.