Case Study: Polarising Beamsplitter Plate for 4550 nm

Case Study: The customer required a polarising beam splitter for 4550 nm for S and P pol at 45°

Customer Challenge: Polarising beamsplitters (i.e. the need to separate S and P polarisations efficiently) is normally achieved using a beamsplitter cube, the cube approach is more harmonious with the laws of Physics in terms of achieving the desired results. However situations occur where a beamsplitter plate is needed as an alternative to the cube, e.g. due to space constraints.

Vortex’s Solution: We have a wide knowledge of materials within the company which means we are able to look at some unique solutions for this problem. We used software simulation to initially study possibilities and arrive at a good solution that could be manufactured repeatedly and could also work for similar applications in the MID IR. The proposed design is then converted into an on plant process which meant we were able to produce the filters quickly.

The Result: The spectral graphs for S and P polarisations are shown below for T and R in Figs 1 and 2, a key feature of this design is keeping s and p performance relatively close to each other. After the initial design study, the work was completed using ‘off-the-shelf’ substrates, the product was coated and diced to the final size on site, with no delays/dependency on sub-contractors.