Third-order optical nonlinearities of Nb4C3 MXene and its application as an ultra-broadband mode-locker

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Vol. 12; no. 3; pp. 893 - 902
• Main Authors: Lee, Kyungtaek, Suh-young, Kwon, Choi, Jaehak, Kim, Jeehwan, Woo, Taeho, Ryu, Janghyun, Jung, Junha, Ju Han Lee
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 18.01.2024
• Subjects: Absorptivity; Broadband; Defocusing; Density functional theory; Doped fibers; Erbium; Fiber lasers; Holmium; MXenes; Nonlinear optics; Nonlinearity; Optical materials; Optical properties; Optical pulses; Optics; Pulse duration; Refractivity; Ring lasers; Short wave radiation; Thulium; Wavelengths
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/d3tc03048b

MXenes have been one of the most extensively investigated nonlinear optical materials at short-wave infrared (SWIR) wavelengths. Herein, we systemically investigated the electronic and optical characteristics of Nb4C3 MXene. First, the electronic and linear optical properties of Nb4C3 MXene were theoretically estimated using density functional theory calculation, thereby revealing the metallic property of Nb4C3 MXene. Through Z-scan measurements, we observed large saturable absorption of Nb4C3 MXene at 1560 and 1910 nm wavelengths. Self-focusing and self-defocusing properties were also observed at 1560 and 1910 nm wavelengths, respectively. The effective nonlinear absorption coefficient and nonlinear refractive index of Nb4C3 MXene were estimated as −(2.27 ± 0.12) × 103 cm GW−1 and (1.3 ± 0.04) × 10−2 cm2 GW−1 at 1560 nm, and −(2.73 ± 0.08) × 104 cm GW−1 and −(0.80 ± 0.01) × 10−1 cm2 GW−1 at 1910 nm. Based on the large and broadband optical nonlinearities, a single broadband saturable absorber (SA) was fabricated to generate optical pulses at SWIR wavelengths. Stable mode-locked pulses 1.66 ps at 1559.8 nm and 1.62 ps pulse duration at 1930.3 nm were generated with a single Nb4C3 MXene-based SA when incorporated in an erbium-doped fiber ring laser cavity and a thulium holmium-doped fiber cavity, respectively. This work indicates that Nb4C3 MXene can be a high-performance material platform for broadband optical devices at SWIR or broader wavelengths.