Mach-Zehnder filter using multiple Si waveguide structure sections for width error tolerance

A Mach-Zehnder interferometer wavelength filter using multiple Si waveguide structure sections showing waveguide width error tolerance is reported. Analytical calculation based on the finite element method shows that the width sensitivity is reduced to 1/30 that of the conventional device. The fabricated device exhibited width sensitivity of dλ/dW = −0.09–0.05 and all the devices on different chips showed identical wavelength response for 1500–1600 nm wavelengths.