Xin He,Rongfei Wei,Xiangling Tian,Jianrong Qiu,Mei Zhang,Qingguang Zeng,Junyan Liu
Te-Bi 2 Te 3 alloy thin film has grown on silicon dioxide substrate by thermal evaporation technique. The Bi 2 Te 3 rhombohedral structure enriched Te in the prepared thin film was identified by high solution transmission electron microscopy (HRTEM), X-Ray diffraction (XRD), Raman spectrum and X-ray photoelectron spectroscopy (XPS). Interestingly, the Te-Bi 2 Te 3 alloy thin film presents a changeover from saturable absorption (SA) to reverse saturable absorption (RSA) as continuously increasing the input intensity, which has been investigated using the open-aperture (OA) z-scan measurement under a femtosecond-pulsed laser at 800 nm. A high modulation depth of 48.3% and large saturation intensity of 24.1GW/cm 2 of the thin film were obtained. Moreover, a large nonlinear absorption coefficient β of ∼10 3 cm/GW is increased with the input intensity elevated. The research results demonstrate that the Te-Bi 2 Te 3 alloy thin film could be an emerging optical material for saturable absorber in Q-switched or mode-locking fiber lasers at low incident intensity while serve as optical limiter at high incident intensity.
Antimonene (Sb), a novel 2D crystalline, has recently received intense attention from optoelectronic communities, due to its enticing physical and chemical properties. Here we systematically investigate the broadband third-order nonlinear optical properties and carrier dynamics in antimonene. Efficient saturable absorption effect was observed at different wavelengths, indicating the use for broadband ultrafast laser generation. The nonlinear refractive indexes were characterized to be (2.55 ± 0.23) × 10 −14 cm 2 /W and (7.88 ± 0.37) × 10 −15 cm 2 /W at 800 nm and 1500 nm, respectively. Photoinduced carrier dynamics are investigated by a non-degenerate transient absorption spectrometer. Fast recovery processes were observed in antimonene and suggesting a high optical modulation speed to 500 GHz.
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