GHz, Octavespanning Photodetectors for MWIR/LWIR

Exploitation of new chip-scale optical frequency comb sources demands improvements in the performance of MWIR/LWIR detectors. These detectors must meet the following specifications: High speed ( < 5 GHz), high-sensitivity (NEP < 1pW/Hz^1/2), broad spectral response (Octave), all at TEC operating temperatures. At present, no single detector exists that meet these demanding performance parameters. InGaAs SWIR pin photodiodes can achieve all of the performance requirements except one: they do not operate at MWIR or LWIR. HgCdTe MWIR/LWIR photovoltaic detectors can meet all of the performance requirements except one: they cannot achieve 5 GHz bandwidth. In this Phase I we will design, manufacture, and test a MWIR (3-6 m ) detector that combines the properties of SWIR pin and MWIR/LWIR photodetectors in a way that harvests the advantages of each, so that all performance requirements are met. Specifically, we will construct a detector with a built-in field in the absorber layer to rapidly sweep out carriers and a barrier diode device architecture to suppress dark current. In Phase II we will extend the design to LWIR, to manufacture both MWIR (3-6 m) and LWIR (6-15 m) prototype devices meeting the performance requirements of the program using TEC cooling.