2x2 Ti:LiNbO3 Integrated Optical Add/Drop Multiplexers utilizing Strain-Optic Effect

Polarization-independent Ti:LiNbO3 2x2 optical add/drop multiplexer for the 1550nm wavelength region is fabricated. The device consists of two input waveguides, two polarization beam splitters, two polarization conversion/electrooptic tuning waveguide sections, and two output waveguides. The single mode channel waveguides for both TE and TM polarizations are fabricated on a x-cut Ti:LiNbO3 substrate by Ti diffusion. Spectral section is based on phase-matched polarization conversion due to shear strain induced by a thick SiO2 grating overlay film. An applied voltage tunes the device by changing the waveguide birefringence, hence the optical wavelength at which most efficient polarization conversion occurs. Tuning rate of 0.094nm/V with a maximum range of 17nm has been obtained. The nearest side-lobe is about 8.2dB. The FWHM is 3.72nm.