8-GHz-bandwidth FM-CW signal generation based on optical modulation technology for W-band radar system

A W-band (75-110 GHz) frequency chirp signal with a bandwidth of 8 GHz and a pulse duration of 1 μs is generated by an optical-modulator-based frequency quadrupler. The high extinction-ratio optical modulator can easily generate a clear optical two-tone signal to form a W-band signal with a high side-mode suppression ratio. The observed degradation of the single-sideband phase noise does not significantly differ from that of the theoretical limit in the frequency multiplication. We demonstrate that the frequency upconversion technique would be beneficial for an analog application that requires quality, such as in a high-precision radar system.