High-speed uni-traveling carrier photodiode for 2 μm wavelength application

Current optical communication systems operating at the 1.55 mu m wavelength band may not be able to continually satisfy the growing demand on data capacity within the next few years. Opening a new spectral window around the 2 mu m wavelength with recently developed hollow-core photonic bandgap fiber and a thulium-doped fiber amplifier is a promising solution to increase transmission capacity due to the low-loss and wide-bandwidth properties of these components at this wavelength band. However, as a key component, the performance of current high-speed photo-detectors at the 2 mu m wavelength is still not comparable with those at the 1.55 mu m wavelength band, which chokes the feasibility of the new spectral window. In this work, we demonstrate, for the first time to our knowledge, a high-speed uni-traveling carrier photodiode for 2 mu m applications with InGaAs/GaAsSb type-II multiple quantum wells as the absorption region, which is lattice-matched to InP. The devices have the responsivity of 0.07 A/W at 2 mu m wavelength, and the device with a 10 mu m diameter shows a 3 dB bandwidth of 25 GHz at -3 V bias voltage. To the best of our knowledge, this device is the fastest photodiode among all group III-V and group IV photodetectors working in the 2 mu m wavelength range. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement