Low Noise, InGaAs Dual Photodiodes for Precise Timing

Conversion of highly stable optical clocks into electrical clocks through photodetection introduces excess phase noise, thereby degrading the frequency stability. This noise is primarily generated due to the conversion of optical intensity noise into electrical phase noise by photodiode¿s non-linearity, specifically power-to-phase conversion. During Phase I, Discovery developed dual photodiodes having a power-to-phase conversion of 3 rad/W at 1550 nm and 900 nm wavelengths simultaneously, which presents a 10 fold improvement in state-of-the-art. During Phase 2, Discovery will optimize the photodiode structure in order to improve its responsivity at 900 nm by a factor of two, while ensuring a 3 dB bandwidth of 18 GHz and power-to-phase conversion of 3 rad/W. This will correspond to a 6 dB improvement in excess phase noise as compared to the Phase 1 photodiodes.