학술논문
광위상배열 기반 빔조향을 위한 도파로 격자 안테나 설계 / Design of waveguide grating antenna for optical phased array based beam steering
Document Type
Dissertation/ Thesis
Author
Source
Subject
Language
Korean
Abstract
본 논문에서는 1550 nm 대역에서 동작하는 실리콘 나이트라이드 기반의양방향 격자 안테나 구조를 제안하고, 제안한 구조를 이용하여 빔조향범위를 향상시켰다. 제안된 양방향 격자 안테나는 32 채널의 격자 주기를포함하는 도파로와 파워를 분배하기 위한 다중 간섭계 커플러가양방향으로 이루어진다. 양방향 격자 안테나는 기존 단방향 격자안테나와 달리 양쪽으로 빛이 전파할 수 있기 때문에 양방향으로 빛을방사할 수 있다. 따라서 교차적으로 빛이 입사할 때, 동일 파장 가변 범위대비해서 2배의 조향 범위를 성취할 수 있는 특징을 갖게 된다. 또한제안된 양방향 격자 안테나는 격자 주기에 따라서 빔조향 각도를 조절할수 있다. 기존의 부피가 크고 무거운 렌즈가 아닌 초박형 평면 렌즈 역할을하는 메타표면 더블렛의 정렬을 용이하기 위해 빔조향 각도를 수직방향으로 내보낼 수 있도록 하였다. 메타표면 더블렛은 나노 구조의비정질 실리콘 단위 셀로 구성되어 있으며, 입사하는 빛의 파면을제어하여 입사 각도의 3배에 해당하는 각도로 투과 시킨다. 이러한메타표면 더블렛이 집적된 양방향 격자 안테나를 이용하여 효과적으로안테나 빔조향 특성을 개선하였다. 제안된 소자들을 적절히 활용하면다양한 분야에서 특화된 특성을 갖게 하여 미래 기술로서 충분히 적용될수 있다. 그리고 무선광통신 분야에서 주목 받기 시작한 광위상배열이광중계기로서 동작할 수 있는지에 대한 신뢰성을 파악하기 위해서 양방향격자 안테나를 응용하여 실험하였다. 양방향 격자 안테나를 통해 수신된10 Gbps 신호는 증폭되어 다시 성공적으로 전송되었다. 본 연구를 통해서근본적인 한계를 극복하여 도파로 격자 안테나의 빔조향 범위를획기적으로 향상 시킬 수 있는 플랫폼을 제시하고 입증하였으며,무선광통신 모듈로서 충분히 잠재적으로 응용될 수 있다는 것을증명하였다.
In this paper, we propose a silicon nitride based bidirectional grating antenna structureoperating in the 1550 nm band, and improve the beam steering range using theproposed structure. The proposed bidirectional grating antenna is bidirectionallycomposed of a waveguide including 32 channels of grating periods and multipleinterferometer couplers for power distribution. Unlike conventional unidirectionalgrating antennas, bidirectional grating antennas can emit light in both directionsbecause light can propagate on both sides. Therefore, when light is incident on eachother, it has a characteristic of achieving twice the steering range compared to thesame wavelength variable range. In addition, the proposed bidirectional gratingantenna can adjust the beam steering angle according to the grating period. The beamsteering angle can be exported in the vertical direction to facilitate the alignment ofthe metasurface doublet, which acts as an ultra-thin flat lens instead of a conventionalbulky and heavy lens. The metasurface doublet is composed of nanostructuredamorphous silicon unit cells and controls the wave front of incident light to transmit atan angle corresponding to three times the incident angle. The bidirectional gratingantenna integrated with the metasurface doublet effectively improves the antennabeam steering characteristics. Appropriate use of the proposed devices can be appliedas a future technology by having specialized characteristics in various fields. Inaddition, in order to demonstrate the feasibility of whether optical phased array, whichhas been attracting attention in the wireless optical communication field, operates asan optical repeater, an experiment was conducted by applying the bidirectional gratingantenna. 10 Gbps signal received through the bidirectional grating antenna wasamplified and successfully transmitted again. Through this study, we have presentedand demonstrated a platform that can significantly improve the beam steering range ofwaveguide grating antennas by overcoming fundamental limitations and prove that itcan be sufficiently applied as a wireless optical communication module.
In this paper, we propose a silicon nitride based bidirectional grating antenna structureoperating in the 1550 nm band, and improve the beam steering range using theproposed structure. The proposed bidirectional grating antenna is bidirectionallycomposed of a waveguide including 32 channels of grating periods and multipleinterferometer couplers for power distribution. Unlike conventional unidirectionalgrating antennas, bidirectional grating antennas can emit light in both directionsbecause light can propagate on both sides. Therefore, when light is incident on eachother, it has a characteristic of achieving twice the steering range compared to thesame wavelength variable range. In addition, the proposed bidirectional gratingantenna can adjust the beam steering angle according to the grating period. The beamsteering angle can be exported in the vertical direction to facilitate the alignment ofthe metasurface doublet, which acts as an ultra-thin flat lens instead of a conventionalbulky and heavy lens. The metasurface doublet is composed of nanostructuredamorphous silicon unit cells and controls the wave front of incident light to transmit atan angle corresponding to three times the incident angle. The bidirectional gratingantenna integrated with the metasurface doublet effectively improves the antennabeam steering characteristics. Appropriate use of the proposed devices can be appliedas a future technology by having specialized characteristics in various fields. Inaddition, in order to demonstrate the feasibility of whether optical phased array, whichhas been attracting attention in the wireless optical communication field, operates asan optical repeater, an experiment was conducted by applying the bidirectional gratingantenna. 10 Gbps signal received through the bidirectional grating antenna wasamplified and successfully transmitted again. Through this study, we have presentedand demonstrated a platform that can significantly improve the beam steering range ofwaveguide grating antennas by overcoming fundamental limitations and prove that itcan be sufficiently applied as a wireless optical communication module.