On-Axis Polarization Coupling in y-Cut Titanium In-Diffused Lithium Niobate SlabWaveguides

摘要

We report on polarization coupling from x-propagating TE-polarized waveguidemodes to TM-polarized radiation modes in y-cut titanium in-diffused lithium niobate slab waveguides. The polarization coupling is linear with respect to the TE-polarized input power and depends on the titanium diffusion time. Furthermore, the polarization coupling was not affected by white light flooding the waveguide. The maximum conversion from a TE-polarized waveguide mode to a TM-polarized radiation mode is 3.2%/cm using a conservative estimate for the power initially in the TE waveguide mode. We observe no turn-on delay greater than 1 s between the excitation of the TE waveguide mode and the observation of the TM radiation. In addition, intentional amplitude modulations of the TE-polarized waveguide mode were registered as equivalent amplitude modulations by the TM-polarized radiation modes. We did not observe polarization coupling from x-propagating TM-polarized waveguide modes to TE-polarized radiation modes.