Broadband polarization-independent infrared photon upconversion within nanophotonic lithium niobate waveguides by higher-order-mode engineering.

A broadband polarization-independent infrared photon upconversion scheme based on nanophotonic waveguides on the lithium niobate on insulator (LNOI) platform is proposed. With the introduction of higher-order-mode dispersion engineering, polarization-independent and broadband photon upconversion with a maximum bandwidth of nearly 46 nm is achieved in this device. The proposed broadband polarization-independent photon upconversion structure shows great potential applications in on-chip infrared photon detection and nonlinear photonics.