Case Study: Polarising Beamsplitter Cube

Case Study: Small volume polarising beamsplitter for Research Institute

Customer Challenge: Customer required a beamsplitter to efficiently split S and P polarisation planes over 2 different wavebands, 775nm and 1550+/-20 nm.

The specification is as detailed in the table above.

Vortex’s Solution: We decided from experience that the best way to achieve these requirements was using a cube beamsplitter, with the dichroic coating on the hypotenuse face and anti-reflection coatings on all 4 entry and exit faces. When the physics of light through prisms is studied, the polarising beamsplitter coating within the cube, has a natural tendency to split into the S and P  polarisation planes, the design can be optimised for both spectral regions simultaneously and the results shared with the customer before any coating is attempted.

Fig 1: Schematic of Polarising Beamsplitter.

The Outcome The spectral results achieved are show in Fig 2 and 3 below. All criteria of the customers initial specification were satisfied, full results and calculations were sent in an excel spreadsheet. The customer was heavily involved in early discussion as we agreed a way to solve the challenge and delighted with the results.