Plate laser beam splitter with mixture-based quarter-wave coating design

Traditionally, a given T/R ratio is achieved by using a non-quarterwave design. We propose a quarter-wave design strategy for arbitrary T/R ratios by using mixture layers with tunable refractive index (n) and optical band gap as high-n layers.

Two quarter-wave PLBS coatings based on Al2O3-HfO2 mixture with a designed T/R ratio of 50:50 are experimentally demonstrated and compared with the traditional PLBS coating. The mixture-based PLBS coating shows good spectral performance, low surface roughness, and high LIDT. For an s-polarized 8 ns pulse laser at a wavelength of 1064 nm, a mixture-based PLBS coating design can improve LIDT by a factor of ~2 with a slightly wider bandwidth.