Design of high isolation CWDM narrow-band pass filter

Abstract

According to the relation between the transmission characteristics and wavelength of coarse wavelength division multiplexer (CWDM), the crosstalk between each channel is considered to lead to the increase of bit error rate between each transmitted signal. The CWDM narrow-band pass filter is coated on glass-ceramics substrate, so that the signal light in 1260-1620nm band has high isolation degree and low cross talk coefficient, and the transmission isolation degree of adjacent channel and non-adjacent channel of reflection band is greater than 40dB. According to the film design theory, TFC membrane system design software was used to optimize the structure of the membrane system, and the method of electron beam evaporation was used to optimize the process parameters and improve the monitoring method, so that the accuracy of the central wavelength was controlled within ± 0.25 nm, which can withstand the test of harsh environment. It has practical value in aviation, aerospace, national defense, communications, environmental protection, analytical instruments and other fields.