我們展示了一種新穎的正面收光累增崩潰光二極體(APD)，該元 件高速和大動態範圍的表現，使其應用於同調光達(Coherent Lidar)擁有出色的性能。藉著局部p型摻雜的In0.53Ga0.47As吸收層和薄的 In0.52Al0.48As累增層(90nm)的優點，在高達8mA的飽和輸出電流下，APD展現出高的光電頻寬(16GHz)和響應度(3.1A/W)，且該元件低過量噪聲(k=0.14)特性確保了其大動態範圍性能。此外，該APD元件的 非線性特性與典型的P-I-N光電二極體完全不同，後者的光電頻寬總 是在飽和輸出時顯著降低，我們展示的APD隨著操作偏壓的上升，可 以抑制光電頻寬在飽和輸出光電流下的劣化，並保持高速操作。作為 光達接收端，需要同時處理來自目標微弱的反射光與光學局部震盪器 強烈的訊號，因此APD優秀的動態/靜態表現，為進一步提高同調光 達接收器的性能開闢了新的途徑。;In this work, we demonstrate a novel top-illuminated avalanche photodiode (APD) with high-speed and wide dynamic range performance for coherent lidar applications. By taking advantag of a partially depleted p-type In0.53Ga0.47As absorbing layer and a thin In0.52Al0.48As multiplication layer (90 nm), the demonstrated APDs exhibit a wideoptical-to-electrical bandwidth (16 GHz) and high responsivity (>3.1 A/W) near the saturation output current which is as high as >8 mA.Furthermore, the measured low excess noise (k=0.15) characteristics of this device ensure its wide dynamic range performance. In addition, it should be noted that the measured nonlinear behaviors of these APDs are quite different from those of typical fast p-i-n photodiodes (PDs), which always show serious degradation in their O-E bandwidths at their saturation output. On the other hand, the measured bias dependent 3-dB O-E bandwidth of the demonstrated APDs can be pinned at 16 GHz without any degradation at around the saturation current output. As the receiving end of lidar, which needs simultaneous processing of weak light reflections from the object and a strong optical local-oscillator (LO) signal. The APDs demonstrated excellent dynamic/static performance,opening up new ways to further improve the performance of coherent lidar receivers.
