Novel Low-Loss Wide-Angle Y-Junctions Of Optical Waveguides With Graded-index Profiles

In recent years, developments of computer network, telecommunications network and cable television network have greatly brought about an advance in large capacity fiber optic communication system, and increased naturally in optical device. In order to reduce the consumption and volume of the optic fiber communication equipments, the optical device of the new structure may become the focus that people pay attention to. The new integrated optics device is even more the developing direction of the optical device. This paper has proposed a novel low-loss wide-angle Y-Junction, reducing size and consumption of the device greatly based on the premise that its loss is relatively small.First, this paper has introduced the development of integrated optics and current situation in low-loss wide-angle Y branch in the world. Then the performances of optical waveguides with graded-index profiles to deflect the light have been calculated, and a low-loss wide-angle Y-junction with the graded-index optical waveguides has been proposed. The different graded-profiles of optical waveguides lead to the different deflection performances of Y branch. As an example three refractive index profiles have been studied and received the corresponding suitable condition, then the design of new Y branch has been given based on the first refractive index profiles.Consider that the simulation method is FDBPM (Finite Difference Beam Propagation Method), this paper has introduced two-dimensional and three-dimensional FDBPM in detail and its key algorithms (LU method and ADI method). The 2D and 3D program have finished and verified with an example.In order to examine the proposed Y branch in theory, novel Low-Loss Wide-Angle Y-Junctions of optical waveguides with graded-index profiles have been simulated in 2D and 3D FDBPM in this paper. In 2D FDBPM losses of Y braches whose branching angles are 20° and 30° are 0.31dB and 0.39dB, respectively. However, the general Y branch whose branching angles are 20° and 30° cannot transmit the light. In 3D FDBPM losses of Y braches whose branching angles are 20° and 30° are 1.46dB and 1.59dB, respectively.At last the novel Y branches have been applied to optical devices and simulated in 2D FDBPM. New 1×4 optical splitter can consist of three novel Y branches whose branching angle are 14.3°. Its length has been reduced greatly based on the premise that its loss is relatively small (0.33dB). In Mach-Zehnder optical modulation consisted of two new Y branches, modulating has been realized and the length of optical modulation has been shortened.The detailed theory and design have been finished about this new Y branch in this paper, and results of lots of simulations have showed that the performances of this novel Y branch are excellent in theory and have established the theoretical foundation for the trial-production of the device.