Waveguide Propagation Based On Yb: YVO <4> And Its Laser Q - Switched Properties

The waveguide is the structure that limit the light propagation in 3D space, and the materials’ refractive index is different. Currently, the integrated photonics is rapidly developing. In order to enhance the photonics information transmission and processing capability, the integrated and miniaturized waveguide is designed.In the paper, the basic structure and preparation method of waveguide was designed.Used the classical optical theory and electromagnetism as the theoretical basis, from the point of geometrical optics, Maxwell equations and boundary conditions, the transmission path of a light wave in the waveguide was obtained and the wave equation was deduced. With the widely application of complex structure waveguide,the ordinary theoretical analysis was very difficult to get the accurate analytic solution.The paper described basic solution of beam propagation method, and used the finite beam propagation method to solve the wave equation, then the mathematical expressions of finite beam propagation method was derived.In order to design low loss, high efficiency waveguide, the Yb:YVO4 crystal was used as the medium material, using Rsoft software simulate the transverse modes of channel waveguide by changing the parameters of waveguide structure. In the Single waveguide, transverse dimension of the spot was controlled by waveguide’s width,and the longitudinal dimension of the spot was controlled by waveguide’s depth.When the width was equal to the depth, the spot was a round spot and if increased their value, the spot size also increased. The result of double-line waveguide was different with the single waveguide, the light field distribution was connected with the double-line distance. And with the increasing of depth and width value, spot size became smaller and then stable, if continue to increase the value, the spot size grow larger.Finally, the passive Q-switching laser performance of Yb:YVO4 crystal was discussed.Producing an average output power was 0.87 W at a pulse repetition rate of 71.4 k Hz,and the slope efficiency was 31.25%. Making use of a Cr4+:YAG crystal plate as the saturable absorber, and its initial transmission was as high as 99.3%. The resulting peak power, pulse energy,and duration, were 0.14 k W, 12.2 J, and 87 ns, respectively.