Optical Vector Analysis Based on Serrodyne Modulation for Arbitrary Responses

An optical vector analysis (OVA) based on serrodyne modulation is proposed and numerically verified by simulations. In the proposed OVA, serrodyne modulation is implemented using a dual-parallel dual-drive Mach–Zehnder modulator to generate asymmetric optical double-sideband (ODSB) signals including a frequency-shifted optical carrier. The generated signals subsequently propagate through the optical device under test (ODUT). Owing to the asymmetric ODSB structure, the proposed OVA is inherently immune to errors induced by the nonlinearity of the electro-optic modulator (EOM). Consequently, the responses of the ODUT can be accurately obtained by processing the frequency-shifted photocurrent, which is converted from the frequency-shifted carrier and the two desired sidebands. Furthermore, the proposed approach overcomes the limitation of conventional optical single-sideband-based OVA in characterizing bandpass responses. Through numerical simulations, the frequency responses of a uniform fiber Bragg grating, a Fabry–Perot cavity, and a bandpass filter are obtained within a bandwidth of 20 GHz. The proposed OVA provides an approach for characterization of optical devices and integrated microwave photonics systems.