Optimal design of DC-based polarization beam splitter in lithium niobate on insulator

Status and Potential of Lithium Niobate on Insulator (LNOI) for Photonic Integrated Circuits

“…Furthermore, the holes in such photonic crystals can introduce significant scattering losses due to the fabrication tolerances, which makes this solution not very attractive. More attractive is the design suggested by Gong et al., who use a directional coupler based design to achieve a PBS. Their simulations suggest that an extinction ratio of 35 dB between the two polarizations is possible.…”

Advances in lithium niobate photonics: development status and perspectives

“…In addition, mode-related devices, 131,244,250,251,255,261,262,267 TO-based devices, [85][86][87] Bragg grating filters, 253,256,257,264 optical true delay lines, 263 and optical phased arrays 260 have also been demonstrated in the LN platform. Most of them rely on the large refractive index contrast available in TFLN.…”

Lithium Niobate on Insulator: An Emerging Platform for Integrated Quantum Photonics

“…For separation of signal and idler photons of different wavelength or polarization, directional couplers made of two coupled waveguides can be used, which have already been designed and implemented on the LNOI platform, [136,214] with 10 s of micrometers in coupling length and sub-micron gap separation. Directional couplers can in principle be made to not have any inherent excess losses, if no sharp bends or strong tapers are introduced, and the total loss is determined by the propagation loss of the waveguides that constitute the coupler.…”

“…[5] For LNOI ridge waveguides, bending radii in the order of a few 10 s of micrometers are suggested to avoid bending losses. [137,214,215] We take a total length of around 200 μm for the directional coupler, including bending and coupling regions, as an estimation of the length needed for having a low-loss directional coupler. In addition it should be mentioned, that the pump pulse could be separated into equal channels for feeding the many sources on the chip, which could be done in a compact way using a cascaded Y-splitter tree, as was already demonstrated on the LNOI platform.…”