Chip-based SBS for image rejection in a broadband microwave photonic mixer

Abstract

Microwave photonics offers a promising solution for frequency converting microwave signals, however, demonstrations so far have either been bulky fibre implementations or lacked rejection of interfering image signals. Here, we demonstrate the first microwave photonic mixer with image rejection of broadband signals utilising chip-based stimulated Brillouin scattering and interferometry. We demonstrate frequency down-conversion of carrier frequencies ranging from 10 GHz-16 GHz, ultra-high image rejection for a single tone of up to 70 dB, and 100 MHz and 400 MHz wide analogue signals with 28.5 dB and 16 dB image rejection, respectively. Furthermore, we down-convert 200 Mb/s quadrature-phase-shift keying signals with an error vector magnitude as low as -9.6 dB when simultaneously present interfering image signals are suppressed by the mixer.

Broadband Microwave Photonic Mixer With High Spurs Suppression and Image Rejection

“…Moreover, the stimulated Brillouin scattering (SBS) effect is introduced into the IRMs [26]- [30]. The SBS gain spectrum of the pump light is used to amplify the +1st-order RF sideband [28] while the loss spectrum is utilized to attenuate the -1st-order RF sideband. As a result, the IF from the undesired image interferes destructively whereas the IF from the desired RF signal is enhanced [29].…”