Microwave photonic signal processing exploiting coherent interactions between Brillouin Stokes and anti-Stokes resonances

Abstract

Generation and processing of RF signals using photonic technologies enable electromagnetic interference (EMI) free low loss, light weight microwave photonic processor [1]. Generation of RF signals is typically achieved by beating multiple optical frequencies, which are created by exploiting nonlinear optical phenomenon in high-Q resonators [2]. RF photonic signal processing, on the other hand, is performed by modulating a laser with the incoming RF signal and processing one of the modulation side bands using active or passive optical resonance to achieve microwave photonic notch filter, RF switch, etc. [3]. Many of these photonics based RF signal processors use a phase modulator or a dual-parallel Mach-Zehnder modulator and a passive filter to create out-of-phase side bands with unequal amplitude. An active or passive resonance is then used to equalize the amplitude of the two out-of-phase sidebands [3, 4]. The resulting destructive interference between the beat signals, which are obtained by beating of the carrier with upper and lower sidebands, results in creation of a rejection band centered at the frequency of equal amplitude. Since the two sidebands are out-of-phase, the induced insertion loss is high because of cancellation in the pass band.