Mini LiNbO₃ multi-function integrated optical device

In order to meet the demand of mini fiber optical gyro for pint-sized devices, the structure of a mini LiNbO₃ multi-function integrated optical device (MIOD) is analyzed and optimized. The loss induced by the curvature of S-bend waveguide and the refractive index difference between waveguide and substrate are simulated by beam propagation method software. The bend loss of S-bend waveguide is decreased by adjusting the parameters of annealed proton exchange. Compared with conventional design, longer bend transition section occupying smaller area is realized by replacing the straight output waveguide with S-bend waveguide directly. The chip length is decreased from 20.0 to 12.5 mm, and the package length is 20.0 mm, which is 2/3 of conventional devices. The typical insertion loss of the mini MIOD is less than 2.5 dB and the loss change from -55 to 85°C is less than 0.2 dB.