Broadband ultrafast photonics of two-dimensional transition metal carbides (MXenes)

This review summarizes recent advances in the photonics of two-dimension transition metal carbides referred as MXenes. MXenes show outstanding nonlinear optical absorption and can serve as excellent mode-lockers to produce ultrafast pulse lasers at the broad range from visible to mid-infrared regions. Particularly, metallic MXenes have great advantages for long-wavelength applications and 3000-nm mode-locked free-space lasers are readily fabricated using MXene-deposited saturable absorber mirrors. MXenes also have significant terahertz electromagnetic shielding efficiency. All-optical modulators using the nonlinear optical properties of MXene are realized at the visible and/or terahertz range. Metamaterials composed of periodically arranged MXene disks can act as broadband perfect absorbers along with surface plasmon enhancement. We believe that these emerging MXene 2D materials will play an important role in variety of future photonic technologies including nonlinear optics, electromagnetic shielding, and plasmonics.