Silicon nitride waveguide polarization rotator and polarization beam splitter for chip-scale atomic systems

The design, fabrication, and characterization of a silicon nitride waveguide polarization rotator beam splitter that operate with extinction ratio (PER) ∼30 dB at the rubidium atomic transition 780 nm wavelength are demonstrated. These devices fabricated on same chip using self-aligned process for integration rib ridge structures. is based mode evolution approach adiabatic tapers demonstrates PER ≥20 over 100 bandwidth (730–830 wavelengths) an insertion loss (IL) ≤1 dB. cascaded tapered asymmetric directional coupler phase matching between fundamental higher order TM modes, whereas TE separated by through port. This provides ≥ 20 IL ≤ 1 50 cross port 15 18 control will enable photonic integrated circuits saturated absorption spectroscopy vapors laser stabilization on-chip.