Mach-Zehnder interferometer cascade comb filter and wavelength division multiplexer/demultiplexer

The invention relates to a cascaded comb filter and a wavelength division multiplexer/demultiplexer of a Mach-Zehnder interferometer, and aims to solve the technical problems that the wavelength division multiplexer of the existing cascaded Mach-Zehnder interferometer is sensitive to introduced wavelength and is not suitable for transverse magnetic waves. The filter comprises n stages of connected comb filtering units, the mth stage of comb filtering unit comprises 2m comb filters, each comb filter comprises a Mach-Zehnder interferometers, and each Mach-Zehnder interferometer comprises a first optical coupling assembly, a transmission waveguide and a second optical coupling assembly which are sequentially arranged in the transmission direction of light waves; the first transmission waveguide in the transmission waveguides is provided with a phase delay waveguide, after the TE polarized light and the TM polarized light pass through the phase delay waveguide, the phase difference between the TE polarized light