根据波导的耦合模理论, 推导出两介质波导单位长度串扰的表达式, 并在一定串扰的前提下, 定义了两介质波导最小间距和最小中心间距, 提出采用最小中心间距做为衡量波导集成度的参量.分析了波导尺寸及折射率差对最小间距、最小中心间距的影响.分析和模拟结果表明: 折射率差越大, 两波导最小间距、最小中心间距越小;在大折射率差的条件下, 两波导最小间距可以降低到1 μm以下;在给定的工作波长、折射率分布的条件下, 两介质波导的最小中心间距存在最小值.

Based on the coupled mode theory, analytical expression of crosstalk per unit length between two dielectric waveguides is derived. The minimum separation and center-to-center separation of two dielectric waveguides under certain crosstalk are defined. The minimum center-to-center separation serves as a measure of waveguide integration. The influences of waveguide size and refractive index difference on the minimum center-to-center separation are investigated. The analysis and simulation results indicate that strongly confined waveguides have small minimum separation and center-to-center separation. Under the condition of large refractive index difference, the minimum separation can be reduced to less than 1 μm. The minimum center-to-center separation has a minimum value for given wavelength and refractive index distribution.