Quarter-Wave Plate Laser Beam Splitter

Researchers have made strides toward improving the performance of mixture-based quarter-wave plate laser beam splitter (PLBS) coatings.

Because of their unique optical properties, plate beam splitters find uses in quantum communication, measurement, and laser systems. The quarter-wave plate laser beam splitter must have a specific spectral performance in high-power laser systems. It also requires a high laser damage threshold to meet laser systems’ ever-increasing output power requirements.

Because of their tunable refractive index and optical bandgap, mixture coating materials have received much attention in the field of high-power laser coatings in recent years. They’ve helped develop and fabricate high-reflective, polarizer, and dichroic mirror coatings. The coating structure of a quarter-wave plate laser beam splitter frequently requires one or more non-quarter-wave layers to achieve a specific intensity-splitting ratio. It increases the electric field intensity and complicates the coating layer thickness.

The researchers achieved mixture material tuning by adjusting the ratio of the two materials. The researchers demonstrated two mixture-based quarter-wave plate laser beam splitters, one with a high-n layer of HfO2–Al2O3 mixture material and one with a low-n layer of SiO2. The surface roughness of the mixture-based PLBS coatings is lower, the intensity-splitting bandwidth is more extensive, and the laser damage threshold is nearly doubled (1064 nm).

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