Mode filter using multimode interference principles: Design and tolerance analysis for accessing waveguides supporting two guided modes

Novel modal filters based on multimode interference have been designed to o vercome the first-order mode influence on future optical network systems fa bricated with waveguides supporting two guided modes. A tolerance analysis for fabrication parameters and design rules with simple formulas are includ ed. Specific designs are carried out in InGaAsP/InP buried waveguides. firs t-order mode greater than 25 dB and 0.1 dB losses at an optimum design leng th of 340 mu m The tolerance ranges are +0.4-0.25 mu m width, - 110 nm + 70 nm wavelength, 20% core quaternary height, and 20% core quarternary materi al gap. (C) 2000 John Wiley & Sons, Inc.