In this work, we demonstrate the high-power and high-responsivity performance of the dual multiplication (M-) layers in In0.52 Al0.48 As based avalanche photodiode (APD). The dual M-layer design in our APD structure effectively constrains the multiplication process to a thin high-field region rather than the whole thick M-layer. It thus minimizes the space charge effect (SCE) within and avoids increasing the tunneling dark current for the case of directly shrinking M-layer thickness in APD. Furthermore, by combining the specially designed mesa shape with this dual M-layer structure, the edge breakdown can be well suppressed. These benefits lead to an ultra-high gain-bandwidth product (450 GHz; 1 A/W at unit gain) and a high saturation current (>12 mA) can be simultaneously achieved in our device. By nonlinearly driving a wavelength sweeping laser in the self-heterodyne lidar setup, it can generate an optical pulse train-like waveform, providing an effective optical modulation depth of 200% to feed into our demonstrated APD at the receiver-end. Under such scheme, the photo-generated RF (1 GHz) power from our APD with a 6.3 A/W responsivity can be as high as +6.95 dBm at a high (7 mA) output photocurrent. Such high-power and highresponsivity characteristics of our APD can further improve the signal-to-noise (S/N) ratio and dynamic range performances in each pixel of the lidar image. A high-quality 3-dimensional (D) FMCW lidar image is constructed based on our APD, without the integration of any electrical amplifier at the receiver end.

We carry out an In0.53Ga0.47As/In0.52Al0.48As single photon avalanche diode which exhibits a single photon detection efficiency exceeding 60% at 1310 nm and neat temporal characteristic of 65 ps. A novel concept of dual multiplication layer is incorporated to avoid the tradeoff between dark count rate, afterpulsing and timing jitter, paving the possibility to improve the overall performance of a single photon detector. Based on this elevated device structure, we further optimize the detection efficiency and timing jitter by employing a delicate mesa structure to better confine the electric field distribution within the central multiplication region. For our detector operated under gated mode, a shorten gate width together with an increase of excess bias percentage leads to a significant improvement in the detection performance. We eventually achieve a single photon detection efficiency of 61.4% without the involvement of afterpulsing at the gating frequency of 10 kHz for 200 K.

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The performance of InGaAs/InAlAs single photon avalanche diodes (SPAD) was improved with fabrication in triple mesa. Current SPADs achieve better dark count rate of 5 × 104 ⁄2 for single photon detection efficiency of 31% at RT.