Ultra-Low Noise Quad Photoreceiver for Space Based Laser Interferometric Gravity Wave Detection

Gravity wave detection using space-based long-baseline laser interferometric sensors imposes stringent noise requirements on the system components, including the large area photoreceiver front ends. The proposed innovation utilizes dual depletion region technology to produce a large area (1mm diameter) 2x2 quad p-i-n InGaAs photodiode array having ~2.1pF capacitance per quadrant. The small capacitance of the quad photodiode array is leveraged in combination with a low-noise JFET-input operational amplifier to manufacture ultra-low noise quad photoreceiver array. Each element (quadrant) of the photoreceiver array will have an input equivalent current noise <2pA/sq.rt. Hz in a frequency range of 2 to 20MHz. This will enable shot noise dominated performance at an optical local oscillator power of ~100mW per quadrant.