Polarisers and beamsplitters

Distributor BFi Optilas has introduced a range of broadband low dispersion polarisers and broadband polarising beamsplitter cubes produced by Precision Photonics. The beamsplitter cubes are derived from a combination of IBS coatings, ultra-precise fabrication capabilities and patent-pending, epoxy-free bonding technology dubbed chemically activated direct bonding (CADB) by the company, resulting in a zero-bondline, zero residue interface at the hypotenuse. Optics produced in this way are environmentally stable and exhibit high laser damage thresholds in both reflection and transmission, making them suitable for high-power broadband, Nd:YAG and fibre laser applications where fluencies are greater than 500mJ/cm² and calcite or cemented cube polarisers cannot be used.

The low dispersion design offers an epoxy-free, broad bandwidth from 700-1,000nm with a low GVD, dielectric coating specifically designed for femtosecond laser applications. The super broadband polariser cube maintains a extinction ratio greater than 500:1 throughout the entire visible to near-infrared (400-1,100nm) wavelength range without sacrificing overall transmission or damage threshold (>6J/cm²).

The distributor has also introduced a range of super-polished fused silica, terbium gallium garnet (TGG), single crystal sapphire (Al2O3) and Ti:Sapphire glass optics, also produced by Precision Photonics. Plano substrates of up to 3-inche diameter can be polished to better than λ/10 surface flatness with 10-5 surface quality and surface roughness of less than 0.1nm RMS. Super-polished or laser quality polished substrates and assemblies are suitable for use in low-loss laser mirrors, high energy waveguides and in cavity ring-down spectroscopy (CRDS) where thermal stability, surface scatter and high laser damage thresholds are key requirements. The company can also provide ion-beam-sputtered (IBS) anti-reflection, beam splitter and high-reflection coatings on these and other materials at wavelengths from 266nm to more than 3μm.

Finally, Bfi has developed broadband anti-reflection (BBAR) coatings for the 3-5μm spectral range capable of extremely high temperature operation and survivability; recent results have demonstrated operational survivability to 1,000ºC. Other examples of custom MWIR IBS (ion-beam sputtering) coatings include plate polarisers for 2.94μm, narrowband AR coatings at 3.4μm and dichroic mirrors with high reflectance at 2.94μm and high transmittance at 1.5μm.