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-μm 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 (-5V) and a high output photocurrent (∼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-μm wavelength.