Research On Efficient And Polarization-insensitive LiNbO₃ Wavelength Converter

Wavelength converters are key devices for future wavelength-division-multiplexing (WDM) systems. Of the several available types of wavelength converters, quasi-phase-matched LiNbO3 (QPM-LN) waveguides are especially promising. This is because these converters provide unique characteristics such as the simultaneous conversion of broadband wavelength division multiplexing channels, a large signal bandwidth, and transparency as regards modulation format. For a long time, the low conversion efficiency is one of the key issues leading to all-optical wavelength converters can't meet the practical application of optical communication system, and the polarization-sensitive also must be removed in practical application. In this paper, we studied the efficient and polarization-insensitive ridge waveguide PPLN wavelength converter. The main contents are as follows. According to the optical waveguide theories, using effective index method, the cut-off conditions are derived. The basic ideas and approximations involved in the FD-BPM approach is explained. Using this method, we simulate the optical field distribution of the ridge waveguide. Taking advantage of the waveguide structure that can simultaneously transmit TE and TM mode, we devised a polarization-insensitive and efficient wavelength converters, and analysed the efficiency and polarization-insensitive ability of DFG,SFG+DFG,SHG+DFG wavelength converters.