Ultra-low Noise, High Bandwidth, 1550nm HgCdTe APD

Voxtel Inc. proposes to optimize the design of a large area, 1.55?m sensitive HgCdTe avalanche photodiode (APD) that achieves high gain with nearly no excess noise. By optimizing the APD device structure and by exploiting the most recent insight into the material?s ionization characteristics, we have engineered the vertical HgCdTe APD for nearly noiseless gain (ultra low k) with high bandwidth and with low dark current. As large area photodetectors necessarily have high dark current and increased capacitance, we will tradeoff the performance of a large area detector design with that of a pixilated design. A pixilated detector can reduce the amplifier noise and dark current in the local of the amplified events to sufficiently low levels for photon counting. Through the use of our low noise, high unit cell density, amplifier integrated circuits, we will demonstrate nearly ideal receiver performance for space optical communications applications.