Nonlinear optical properties of PVD-grown Cr2Te3 film and its nonlinear switching application

Recently, two-dimensional (2D) nanomaterials have been investigated extensively in the field of nonlinear photonics. Cr2Te3, which is one of the 2D transition metal chalcogenides, has garnered attention in the field of spintronics and optoelectronics because of its fascinating magnetic and optical properties. Despite its potential in optoelectronics, Cr2Te3 has rarely been studied in the field of nonlinear photonics. This study investigates the nonlinear optical responses of nanoscale-layered Cr2Te3 films grown by physical vapor deposition at telecommunication wavelengths. A large nonlinear absorption coefficient of –(1.43 ± 0.06) × 105 cm/GW and a nonlinear refractive index of –1.22 ± 0.04 cm2/GW at 1560 nm obtained through Z-scan measurements indicate that the Cr2Te3 film shows saturable absorption and self-defocusing properties at telecommunication wavelengths. Density functional theory calculation show that Cr2Te3 is suitable for broadband optical device. The potential of the nanoscale-layered Cr2Te3 film as a base medium for a nonlinear optical switch was evaluated by fabricating a saturable absorption mirror (SAM). Stable Q-switched pulses with a maximum repetition rate of 33.35 kHz and minimum temporal width of 2.62 μs were readily achieved from a fiber laser cavity incorporating the SAM.