Narrow band mach-zehnder filter.

摘要

A Mach-Zehnder filter passes a signal, the wavelength spectrum of which is centred about a wavelength lambda(f). The filter comprises an input coupler device for splitting an input signal into N equal simultaneously propagating output signals, where N > 2. A combining device combines N optical signals into a single output signal. N optical waveguide paths connect the N outputs to each of the N waveguides. The light propagating through the waveguides is subjected to a delay that is different from the delay experienced by light propagating through each of the other waveguides. The waveguide paths have the same length and have different refractive index profiles.