Magneto-optical Grating Of Adjustable Comb Filter Characteristics

With the development of photonics, optical material and technology, all-optical signal processing technology has been becoming the research focus, the new devices with all-optical signal processing functions have been paid more and more attention. As a novel period-coupling waveguide structure with the magneto-optical effects, the magneto-optical gratings are of flexible controllability, and multi-function with potential applications to the fileds of optical communication, optical sensing, and optical signal processing, etc.In this paper, the characteristics of tunable comb filter and the jitter performance of the magneto-optical fiber Bragg grating (MFBG) are analyzed and its application in all-optical clock extraction is investigated. The main contents and innovations are as follows:1. The dependence of reflection spectrum of mode-converted light on magneto-optical coupling coefficient in the MFBG is studied according to the mode-coupled theory for the MFBG. By adjusting the magnetic field or changing the magneto-optical coupling parameter, the position of the photonic band gap can be controlled, and then the function of turnable comb filter is achieved. When the magneto-optical coupling parameter is changed in the range of 0¹.3m^-1, the free spectral range keep fixed basically.2. According to the normalized rms amplitude jitter formula of the F-P filter, the amplitude jitter performance of the MFBG filter is analyzed. The analysis shows that adjusting the magneto-optical coupling parameter can improve the jitter performance of the MFBG filter.3. The clock extrantion of 40Gbps RZ data signal by utilizing the comb filtering of cascaded MFBGs under bias magnetic fields is simulated. The influence of the magneto-optical coupling parameter and the wavelength stability of laser on the extracted clock is also analyzed; meanwhile, it shows that the magneto-optical grating filter has the advantages of simple, magnetic-controlled, etc.