Study And Fabrication Of Multi-band Filters In Laser Communication System

The multi-band filters is mainly used in the laser communication system. For the special requirements of optical system in laser communication system, chose Ti3O5 and SiO2 as high/low refractive index materials. On both sides of the K9 glass substrate whose diameter is 25 mm, thin films were designed by the film design software TFCalc. Thin films were prepared through electron beam evaporation method and ion-assisted deposition technique, and the thickness of the filter was controlled by using crystal-controlled. By repeatedly optimizing technical parameters, the filter is prepared successfully. The transmittance of 532 nm was 97.8%, the transmittance of 808 nm was 0.3%, the transmittance of 1064 nm was 97.6% and the transmittance of 1550 nm was 97.5%. In the course of the research, the problem that the spectral curve drifted to the short wavelength was solved by modifying Factor Tooling. The problem of the ripple of the pass band was solved by removing the residual evaporation. Through all the tests, the multi-band filter meets the requirements of the optical system.