Microwave photonic photorefractive smart filters

This paper reviews our past and current work on microwave photonic photorefractive smart filters (MWP-PSFs). These devices rely on the generation of dynamic Bragg gratings inside InP:Fe 1.55-μm photorefractive crystals. First, we concentrate on the applications of MWP-PSFs to optical measurements. We report a 15-pm resolution optical spectrum analyzer without mechanical tuning and a 0.2-nm passive wavelength spaced controller. Secondly, we describe the extension of the MWP-PSF concept to the radio modulation frequency control of fiber-wireless systems. Then, we outline the recent proposal of a wavelength self-tunable single-sideband (WST-SSB) filter in order to compensate for the effects of fiber chromatic dispersion in fiber-radio systems. The performance of the latter device is extensively examined in a fiber-radio 140-Mbit/s data transmission employing binary phase-shift keying modulation at 16 GHz without intermediate frequency. Finally, possible future developments such as the InGaAsP integration of MWP-PSFs and the use of a new photorefractive material are discussed.