Back-to-Back UTC-PDs With High Responsivity, High Saturation Current and Wide Bandwidth

A novel back-illuminated mesa-structure back-to-back uni-traveling-carrier photodiode (UTC-PD) is proposed and realized. By stacking two UTC-PDs to form a PINIP structure, high responsivity, high output saturation power, and wide bandwidth are achieved simultaneously. The responsivity of a 24-μm -diameter device is as high as 0.86 A/W, and a 3-dB bandwidth up to 28.3 GHz is attained. The saturation current up to 62 mA at 1-dB compression point is demonstrated at the frequency of 24 GHz.