Ultra-low noise large-area InGaAs quad photoreceiver with low crosstalk for laser interferometry space antenna

摘要

Quad photoreceivers, namely a 2 x 2 array of p-i-n photodiodes followed by a transimpedance amplifier (TIA) per diode,are required as the front-end photonic sensors in several applications relying on free-space propagation with position anddirection sensing capability, such as long baseline interferometry, free-space optical communication, and biomedicalimaging. It is desirable to increase the active area of quad photoreceivers (and photodiodes) to enhance the link gain,and therefore sensitivity, of the system. However, the resulting increase in the photodiode capacitance reduces thephotoreceiver's bandwidth and adds to the excess system noise. As a result, the noise performance of the front-end quadphotoreceiver has a direct impact on the sensitivity of the overall system. One such particularly challenging applicationis the space-based detection of gravitational waves by measuring distance at 1064 nm wavelength with ~ 10 pm/√Hzaccuracy over a baseline of millions of kilometers.We present a 1 mm diameter quad photoreceiver having an equivalent input current noise density of & 1.7 pA/√Hz perquadrant in 2 MHz to 20 MHz frequency range. This performance is primarily enabled by a rad-hard-by-design dualdepletionregion InGaAs quad photodiode having 2.5 pF capacitance per quadrant. Moreover, the quad photoreceiverdemonstrates a crosstalk of & -45 dB between the neighboring quadrants, which ensures an uncorrected direction sensingresolution of & 50 nrad. The sources of this primarily capacitive crosstalk are presented.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.