Semi-vectorial analysis of a compact wavelength demultiplexer based on the tapered multimode interference coupler

• 来源期刊: 中国物理（英文版）
• 关键词: wavelength demultiplexer multimode interference beam propagation method photonic integrated circuits
• 年，卷（期）: 2007,（7）
• 页码范围: 2015-2022
• 页数: 8页
• 语种: 英文

摘要

Based on a parabolically tapered multimode interference(MMI) coupler with a deep-etched SiO2/SiON rib waveguide, a compact wavelength demultiplexer operating at 1.30 and 1.55μm wavelengths is proposed and analysed by using three-dimensional semi-vectorial finite-difference beam propagation method (3D-SV-FD-BPM). The results show that a MMI section of 330.0μm in length, which is only 76% length of a straight MMI coupler, is achieved with the contrasts of 42.3 and 39.2dB in quasi-TE mode, and 38.4 and 37.8dB in quasi-TM mode at wavelengths 1.30 and 1.55μm,respectively, and the insertion losses below 0.2dB at both wavelengths and in both polarization states. The alternating direction implicit algorithm with the Crank-Nicholson scheme is applied to the discretization of the 3D-SV-FD-BPM formulation along the longitudinal direction. Moreover, a modified FD scheme is constructed to approximate the resulting equations along the transverse directions, in which the discontinuities of the derivatives of magnetic field components Hy and Hx along the vertical and horizontal interfaces, respectively, are involved.