Narrow band Mach-Zehnder filter

摘要

A Mach-Zehnder filter includes an input coupler for splitting an input signal into N equal output signals, where N>2, and a signal combining coupler for combining N optical signals into a single output signal. It further includes N optical waveguide fibers for connecting the N outputs from the input coupler to the signal combining coupler. Each of the N optical fibers subjects the light propagating therethrough to a delay that is different from the delay experienced by light propagating through each of the other optical fibers. This Mach-Zehnder filter exhibits greater finesse per stage than previous Mach-Zehnder devices, finesse being the ratio of the wavelength separation between adjacent peaks to the peak widths.