Research on Optimal Design of Ultra-Bandwidth Multi-channel Filter Based on Fabry-Perot Structure

Abstract Aiming at the traditional cascade structure, this paper studies the dielectric film filter with potential application prospect on the basis of Fabry-Perot structure, and designs a new type of multichannel wavelength division multiplexer, which avoids the disadvantage that a single filter can only pass through a specific single wavelength. In this paper, an optical filter based on thin film interference is designed for a multi-channel optical communication system with Nb2O5 and SiO2 materials for 1550 nm operation. Based on the optical film theory of the Fabry-Perot structure, the evaluation function can be minimized by changing the thickness of the film structure and the spacer layer, using the TFCalc film design software for calculation and analysis, and using the optimization design command to make the program change the film thickness or other parameters, thereby designing a multi-channel filter film. The results show that the filter film with 200 peak channels is realized in the ultra-wide band of 1460–1620 nm, and the transmittance at the most concave part of the peak ripple reaches 92%. It can be found that this design has a larger number of peak channels and a smaller insertion loss, which can achieve multi-channel signal multiplexing more effectively.