Silicon microring modulator-based RF mixer for millimeter-wave phase-coded signal generation.

Phase-coded radio frequency (RF) pulses are widely adopted for radar systems as an effective signal format to enable high-range resolution. However, generating such signals conventionally requires high-speed electronics and complex RF circuitry that impose burdens on the system cost and power consumption. In particular, modern radar systems desire features such as high frequencies, e.g., in the millimeter-wave region, high compactness, and high system flexibility, which pose great challenges for the conventional all-electronics solutions. In contrast, integrated microwave photonics opens a way to solutions that are able to provide those features simultaneously, together with potential for full integration and low cost fabrication. Here, we present an integrated microwave photonic method of a binary-phase-coded millimeter-wave signal generation. The core device is a silicon microring modulator with a device size of 0.13  mm×0.32  mm and a modulation bandwidth of 23 GHz. Using RF seed frequencies of 17.5 GHz and 20 GHz, respectively, we experimentally demonstrated the generation of binary-phase-coded signals at 35 GHz and 40 GHz using our proposed approach, the performance of which was verified by a pulse compression ratio of 94 and 106, respectively. The result of this work points to the realization of a chip-scale flexible millimeter-wave signal generator.