Phase controlled frequency switchable optoelectronic oscillator based on a tunable microwave photonic filter for RADAR system

This paper proposes and demonstrates a voltage-induced phase-controlled, switchable, and widely tunable optoelectronic oscillator (OEO) without using any electrical filter, by adjusting the DC bias voltage of one MZM of the dual-parallel Mach–Zehnder modulator (DPMZM) architecture. The proposed scheme is based on a DPMZM, an SFBG (specialized fiber Bragg grating), and a double-loop OEO architecture, leading to a carrier phase-shifted double-sideband modulation scheme. The high-Q microwave photonic filter (MPF) has been realized to lock the oscillating frequency by using a dispersive SFBG in conjunction with a double-loop OEO architecture. The center frequency of MPF can be tuned not only by tuning the wavelength of the laser source or the chromatic dispersion parameter of the dispersive element but also by simply adjusting the DC bias voltage of DPMZM. The frequency tunability and phase noise performance are investigated, followed by a proof-of-concept experiment. The present study provide the option to generate the switchable (fm or 2fm) microwave signal fully controlled by the DC basing of the modulators.