Optoelectronic Oscillator in Multimode Regime: Tunable Optical Frequency Comb Generation

A method for generating an optical frequency comb in an optoelectronic oscillator is proposed and investigated. It is based on the modulation expansion of a laser line using large modulation indices. In the proposed scheme, a double-microwave-input amplitude modulator is used in a single-loop optoelectronic oscillator instead of a usual amplitude modulator, and an optical output is arranged after it. The circuit characteristics and parameters of the formed optical frequency comb and microwave oscillation are investigated using numerical simulation, which allows us to study highly nonlinear and multimode regimes. The advantage of the scheme is an easy control of all parameters of the optical frequency comb by changing the frequency of the CW laser, the average frequency of the microwave bandpass filter, and the amplitudes of the modulating signals applied to the modulator arms.