High-efficiency three-port beam splitter of reflection grating with a metal layer

• The reflective 1 × 3 beam splitter by a metal-based grating.
• Efficiencies of 32.37%/32.28%/32.37% for TE polarization.
• Efficiencies of 32.30%/32.35%/32.30% for TM polarization.

We describe a novel reflection three-port beam splitter by a microstructure grating, which can show high efficiency for both TE and TM polarization in the 0th and the ±1st orders. The grating profile is optimized by using the rigorous coupled-wave analysis (RCWA) at telecom wavelength around 1550 nm. With the optimized grating profile, the reflection three-port beam splitter can work as a 1 × 3 beam splitter for not only TE polarization but also TM polarization. Efficiencies can reach nearly 33% in the 0th and the ±1st reflected orders. The presented reflection three-port beam splitter grating should be a useful element in numerous practical applications, and a duty of 0.5 would make it easy to be fabricated.