The Photonic Devices Group focuses on developing novel optoelectronic devices with emphasis on photodetectors. The research projects tend to fall into two broad areas: high-sensitivity photodetectors, e.g., avalanche photodiodes and high-power photodiodes. The avalanche photodiode projects include ultraviolet detectors for applications such as biological agent detection, nuclear radiation sensors, and cosmic ray detection. In the short-wavelength infrared the primary thrust is high-speed, low-noise detectors for fiber optic communications. In the mid-wave spectrum, ultra-low-noise detectors for imaging arrays have been developed. Recently, an avalanche photodiode that mimics a photomultiplier tube has been achieved. The quantum limits that determine the performance parameters of single photon detectors are being studied.
Microwave photonics has demonstrated the potential to significantly influence a wide range of applications including analog fiber optic links, optically-fed antenna arrays, optical analog-to-digital converters, arbitrary waveform generation, and low phase noise microwave signal generation thanks to its large instantaneous bandwidth, the low attenuation of optical fibers, continuous spectral coverage, enhanced signal processing capabilities, as well as size, weight, and power consumption. The focus of the Photonic Devices Group has been to develop photodiodes that operate at high optical input power and high bandwidth. Recent work has included developing high-power photodiodes with high linearity. In order to incorporate these photodiodes with Si photonic integrated circuits, heterogeneous integration techniques have been employed.