NEC Develops New Avalanche Photodiodes (Research Review)
A team made up of T Nakata and colleagues at NEC Corporation, Japan are currently developing waveguide avalanche photodiodes (APDs) to address the high sensitivity and low operation voltage requirements of receivers in optical networking components. The waveguide design is normally used with high-speed 40 Gbit/s pin photodiodes because it enables high quantum efficiency and high-speed operation simultaneously. The waveguide structure is also combined with a thin 0.1 m InAlAs multiplication layer, which should provide a high gain-bandwidth product. The InAlAs waveguide APD has achieved a low operation voltage of 15 V, quantum efficiency of 76%, multiplied dark current of 40 nA @ M = 10, bandwidth of 32 GHz and a gain-bandwidth product of 180 GHz. A 10 Gbit/s APD receiver managed to achieve a sensitivity of 28.8 dBm (for a bit-error rate of 109) one of the highest sensitivities achieved for such a device (see ). The researchers describe their findings in Electronics Letters 36(24) p2033.