Integrated polarization beam splitters in the silicon nitride platform for 950 nm and 1300 nm wavelengths

Photonic integration in a silicon nitride (SiN) platform enables low propagation losses and a wide transparency range, making it ideal for quantum applications. However, polarization control in SiN is challenging because of its low birefringence. This work demonstrates polarization beam splitters using asymmetric directional couplers in SiN, designed for 950 nm and 1300 nm wavelengths. These devices exhibit low insertion losses (<1 dB) and high polarization extinction ratios (20 dB–30 dB).