Broadband Saturable Absorption Response of Metallic (Nb and Ta) Carbides for Photonic Devices

Metallic carbides such as NbC and TaC, as emerging 2D materials, show excellent conductivity, broadband linear optical response, as well as strong light-matter interaction. However, exploring the nonlinear optical properties of the NbC and TaC is still absent in the optical communication band, which is desirable to boost the development of broadband photonic devices. Herein, dispersion-less broadband saturable absorption in the near-infrared wavelength in both NbC and TaC by a Z-scan system is observed. The nonlinear absorption coefficients of NbC and TaC are superior to those of graphene, Nb₂C, and Ta₂C MXenes, which can be described well with a three-level model. Motivated by the excellent saturable absorption property in the near-infrared region, all-optical modulators with high modulation depth as well as Q-switched lasers with µs-level pulse width at 1550 nm are successfully achieved. This work suggests a great potential of metallic carbides for high-performance of photonic devices.