Frequency-hopping signal generation in an active time-domain mode-locking optoelectronic oscillator.

A controllable frequency-hopping (FH) optoelectronic oscillator (OEO) based on active time-domain mode-locking (TDML) is proposed and experimentally demonstrated. In the proposed FH OEO, a dual-passband microwave photonic filter (MPF) based on phase-modulation-to-intensity-modulation (PM-IM) conversion is implemented using two laser diodes (LDs), a phase modulator, a micro-disk resonator, and a photodiode. Using two synchronized electrical control signals, the two LDs are intensity modulated to achieve the controllable two sub-passbands of the dual-passband MPF. Setting the frequencies of the two control signals equal to an integral multiple of the OEO free spectral range to achieve the TDML, a controllable FH signal generation scheme is achieved in the proposed FH OEO without the mode competition effect. In the experiment, a binary FH signal with controllable time duration, carrier frequency, and repetition period of the sub-signals is generated. The two sub-signals of the generated FH signal with an FH speed of about 21 ns, a time duration from 1% to 99% of 14.75 s, a frequency range from 6 GHz to 18 GHz, and a repetition period from 14.75 s to 147.5 ns are successfully demonstrated.