High-speed, high-responsivity, and high-power performance of near-ballistic uni-traveling-carrier photodiode at 1.55-μm wavelength

In this letter, we demonstrate a novel photodiode at a 1.55-mu m wavelength: the near-ballistic uni-traveling-carrier photodiode (UTC-PD). After a p(+) delta-doped layer was inserted into the collector of a UTC-PD, near-ballistic transport of photo-generated electrons under high reverse bias voltage (-5 V) and a high output photocurrent (similar to 30 mA) was observed. The demonstrated device has been combined with an evanescently coupled optical waveguide to attain high responsivity and high saturation power performance. Extremely high responsivity (1.14 A/W), a high electrical bandwidth (around 40 GHz), and a high saturation current-bandwidth product (over 1280 mA (.) GHz, at 40 GHz) with high saturation radio-frequency power (over 12 dBm at 40 GHz) have been achieved simultaneously at a 1.55-mu m wavelength.