Optical wireless data transmission is an emerging complementary technology compared to the RF transmission in 5G and 6G communications. The optical phased array (OPA) would be a promising component for such high-speed wireless transmission requiring beam-steering function. We achieved 25Gbps data transmission using silicon-based OPA and commercialized photodetector (PD). OPA was designed as 64 channels having output beam divergence angle less than 1 for both horizontal and vertical direction. The diverging beam is received by high-speed PD with active diameter less than 30μm. The demonstration of 20Gbps data transmission was practiced with OPA’s output beam power as 0dBm and a freespace range of 1.5m. Received signal from photodetector has an eye-diagram with an extinction ratio of 5dB. Depending on our link power budget, higher output beam power and smaller beam divergence angle concludes to longer free-space range and larger bandwidth. Improvements on beam concentration by lens system could also increase range and bandwidth.
Optical phased array (OPA) is considered as promising device in LiDAR application. We implemented a 1x16 silicon OPA consisting of an array of p-i-n electro-optic phase shifters and thermo-optic tunable grating radiators capable of two-dimensional beam-steering. The OPA was fabricated with CMOS-compatible process using SOI wafer. The p-i-n electro-optic phase shifters were formed in OPA channels for transversal beam-steering. With an array pitch of 2 μm, we attained transversal steering up to 45.6° at 1550 nm wavelength. For longitudinal beam-steering, we employed thermo-optic tunable grating radiators with p-i-n junction. The i-region covers whole radiator array and the p- and n-doped regions are placed on the both sides of the radiator array. This structure can provide fairly uniform heating of the radiator region, shifting the overall radiation field in longitudinal direction by the thermo-optic effect. As a result, a longitudinal beam-steering up to 10.3° was achieved by forward-biasing with a power consumption of 178 mW. This result proves a possibility of wide two-dimensional beam-steering with one-dimensional OPA without using tunable light source. We confirmed that the longitudinal tuning range obtained above is corresponding to near 100 nm wavelength tuning. Our device scheme can be a cost-effective solution of the OPA and also be a solution of self-adjustment for fluctuation of the wavelength-dependent performances.
Camera ego-motion is computed utilizing optical flows which are obtained from sparsely located feature points, where the corresponding points are determined through the information fusion of the correlation and the system model-based prediction. Since the ego-motion of the camera is obtained utilizing optical flows, the accuracy of recognized motion depends highly on the correctness of optical flows. Therefore, the ego-motion utilizing feature-based optical flows are more reliable than those of other points due to the distinctive characteristic of feature points. The technical bottleneck of this category of solution is the matching of corresponding points. In this paper, the correlation and prediction is fused to determine trustable matching pairs. For better prediction, system dynamic model is employed. The effect of the proposed algorithm has been shown through the motion estimation of the camera installed on a dynamic system.