Linearity Characteristics of Avalanche Photodiodes For InP Based PICs

We demonstrate InP PICs with avalanche photodiodes (APD) consisting of InP and InAlAs multiplication regions and investigate these devices regarding their DC and RF linearity characteristics. The optical input dependent gain, bandwidth and output power are characterized and compared to electric field simulations. The space-charge induced electric field reduction is considered to determine the measured properties of the APDs. The APDs with an InAlAs multiplication region exhibit a high bandwidth of 27 GHz in combination with high sensitivity for optical input powers low as 34 µW at a responsivity of 0.65 A/W and a dynamic range of 34 dB. Although the APD with an InP multiplication region shows lower bandwidths of maximum 6 GHz, it demonstrates a high sensitivity for input powers low as 26 µW at a responsivity of 0.85 A/W and a dynamic range of 30 dB making it very attractive for sensing applications. Further, the bias and optical input dependent electric field help to conclude the linearity limitations of the presented devices.