Electro-optic parametric circuits as low-noise millimiter-wave receivers

Various microwave photonics platforms have been proposed for transmitting, filtering, channelizing, processing, generating, and detecting radiofrequency and microwave signals. Despite the large bandwidths, low losses, and sensitive detection available with optical carriers, these platforms suffer from large noise figures due to the low electro-optic modulation efficiencies. Consequently, the use of microwave front ends with high-gain, Low-Noise Amplifier (LNA) stages is essential. In this work, we argue that co-designed microwave and photonic integrated electrooptic modulator (EOM) circuits, can serve as amplifierless millimeter-wave receivers with low noise figures comparable to those of state-of-the-art LNAs. We find that resonant EOMs, similar to transistors, have an optimal input impedance that minimizes noise temperature. Noise figures under 4.9 dB (9.5 dB) at 100 GHz are theoretically predicted in optimally designed resonant (traveling-wave) thin-film lithium tantalate modulators pumped with 0.6 mW (300 mW) laser power.