Research On SOI Waveguide Optical Polarization Beam Splitter

In the era of optical information,polarization beam splitter,as the core component of all optical network,has been widely concerned.Silicon-based optical waveguide polarization beam splitter has many advantages in the aspects of device integration and process compatibility due to the existence of planar lightwave circuit(PLC)technology,leading to an extremely broad application prospect and a huge market potential.In this thesis,a type of asymmetric Mach-Zehnder interference(AMZI)polarization beam splitters on the silicon-on-insulator(SOI)waveguide platform is studied.In this work,we fist investigate and analyzed the mechanism of refractive index change caused by bending structure of waveguide,transform the bending waveguide an equivalent straight waveguide by conformal transformation method,and achieve the refractive index distribution formula of straight waveguide with a conformal transformation,and consequently obtain the formula for defining the refractive index change of bending waveguide.Then,we introduce the theory of refractive index change caused by a bending waveguide into the AMZI construction to create a controllable optical phase difference between two arms,and consequently establish a theoretical model for defining the independent outputs of both TE-and TM-mode at two output ends.Via the MATLAB programmable numerical simulations,an AMZI type polarization beam splitter is designed needs neither an outside modulation effect nor a manufacture of extra-structures.Further,the Finite-Difference Beam Propagation Method(FD-BPM)software is used to simulate and optimize the performance of SOI waveguide AMZI type polarization beam splitter.The results show that when the refractive index of Si O2 material is 1.45509,the thickness of Si O2 material is 3.0 μm,the core Si material has a refractive index of 2.95,the inner ridge height is 1.2 μm,the outer ridge height is 2.0 μm,and the ridge width is 1.5～2.0 μm,the expectable splitting function is achieved,where the extinction ratios of the TE-and TM-mode are 26 d B and 25 d B,respectively,implying that the device structure can realize the device function of polarization beam splitting.Finally,we select an appropriate device structure to fabricate samples and experimentally test the performance,summarize the results,and propose a device performance improvement scheme.