Broadband Non-Polarizing Cube Beamsplitters

Broadband non-polarizing hybrid cube beamsplitters have moderate absorption but minimal polarization sensitivity. The broad spectral flatness of these beamsplitters makes them ideal for use with multiple sources or tunable lasers. Incoming beams are both transmitted and reflected 45%, with the s and p-polarized components matched to within 10% of each other. Hybrid beamsplitters are less sensitive to changes in angle of incidence, resulting in an optic that is chromatically neutral for both convergent and divergent beams.

These beamsplitters consist of a pair of precision right-angle prisms carefully cemented together to minimize wavefront distortion. The hypotenuse of one of the prisms is coated with a metal-dielectric hybrid beamsplitter coating optimized over a broad wavelength range. The four faces are antireflection coated with a broadband multilayer dielectric coating to minimize surface reflection losses over the wavelength range. Due to the metallic nature of the hybrid coating, these beamsplitters are not intended for use with higher power lasers.

Cube beamsplitters are formed by cementing two right angle prisms together. One of the two prisms has the partially reflective metal-dielectric coating applied to its hypotenuse. In Newport's cube beamsplitters the coated prism is marked with a visible dot. Incident light should enter the prism with the coated hypotenuse in order to minimize power passing through the optical cement. Alternatively, a beam entering via the uncoated prism results in more than triple the fluence in the cement (the transmitted component, plus a double pass by the reflected component). With higher power beams this can result in degradation of the cement.

Three metal-dielectric hybrid broadband coatings are offered covering the 400–700 nm (shown), 700–1100 nm, and 1100–1600 nm wavelength ranges.