Brewster Angle Polarizing Beamsplitter Laser Damage Competition: 'P' polarization

摘要

Brewster angle plate polarizing beamsplitters play a critical role in splitting and combining beams within high power laser systems. A laser damage competition of polarizer beamsplitter coatings creates the opportunity to survey the current laser resistance these coatings within private industry, governmental institutions, and universities by a direct comparison of samples tested under identical conditions. The requirements of the coatings are a minimum transmission of 95% at "P" polarization and minimum reflection of 99% at "S" polarization at 1064 nm and 56.4 degrees angle of incidence. The choice of coating materials, design, and deposition method were left to the participant. Laser damage testing was performed according to the ISO 11254 standard utilizing a 1064 nm wavelength laser with a 10 ns pulse length operating at a repetition rate of 20 Hz. A double blind test assured sample and submitter anonymity so only a summary of the results are presented. In addition to the laser resistance results, details of cleaning methods, deposition processes, coating materials and layer count, and spectral results are also shared. Because of the large number of samples that were submitted, damage testing was conducted at "P" polarization only with "S" polarization damage testing reserved for next year on these submitted samples. Also the samples were only tested in the forward propagating direction; specifically samples were irradiated from air as the incident medium, through the thin film, and then through the substrate. In summary, a 6:1 difference existed for "P" polarization damage fluences amongst all of the competitors with the dominate variables that impacted the laser resistance being the deposition materials, deposition process, and cleaning method.