A flexible wide bandwidth electro-optic probing system using a recirculating frequency shifter

In this paper, we study the performance of a wide-bandwidth electro-optic probing system based on an optical comb generated with a recirculating frequency shifter. The system beats a single harmonic from the optical comb with an optical sideband from a RF signal to yield a lower frequency wave. The use of a tunable laser, tunable optical filters and single-sideband modulator gives the system a great flexibility, potentially allowing to down-convert THz frequencies down to a few GHz. Noise floor, IF signal bandwidth and coherence length are studied.