Tunable Broadband Nonlinear Optical Properties of Black Phosphorus Quantum Dots for Femtosecond Laser Pulses

Abstract

Broadband nonlinear optical properties from 500 to 1550 nm of ultrasmall black phosphorus quantum dots (BPQDs) have been extensively investigated by using the open-aperture Z-scan technique. Our results show that BPQDs exhibit significant nonlinear absorption in the visible range, but saturable absorption in the near-infrared range under femtosecond excitation. The calculated nonlinear absorption coefficients were found to be (7.49 ± 0.23) × 10−3, (1.68 ± 0.078) × 10−3 and (0.81 ± 0.03) × 10−3 cm/GW for 500, 700 and 900 nm, respectively. Femtosecond pump-probe measurements performed on BPQDs revealed that two-photon absorption is responsible for the observed nonlinear absorption. The saturable absorption behaviors observed at 1050, 1350 and 1550 nm are due to ground-state bleaching induced by photo-excitation. Our results suggest that BPQDs have great potential in applications as broadband optical limiters in the visible range or saturable absorbers in the near-infrared range for ultrafast laser pulses. These ultrasmall BPQDs are potentially useful as broadband optical elements in ultrafast photonics devices.

Controlled Synthesis of 2D Palladium Diselenide for Sensitive Photodetector Applications

“…Obviously, the photocurrent of our heterojunction devices under DUV, NIR, and MIR light illuminations with pronounced response are all enhanced by 1–2‐folds. The enhancement in MIR photoresponse is possibly due to the defects in the BPQDs that are capable of absorbing IR light and forming photocurrent under IR illumination . Another contributory factor is related to transition of electron from the valence band of BPQDs to the Fermi level of PdSe 2 , which has been observed in other vdW heterojunction photodetectors made of MoTe 2 –MoS 2 , WSe 2 –MoS 2 , and so on.…”

Synthesis Techniques, Optoelectronic Properties, and Broadband Photodetection of Thin‐Film Black Phosphorus

“…Moreover, due to the decent optical absorption, thin‐film BP has also been widely applied for mid‐infrared ultrafast photonics as saturable absorbers. [ 199–204 ]…”

Recent advances in low‐dimensional semiconductor nanomaterials and their applications in high‐performance photodetectors

“…Because of the dimensions and the edge states, BPQDs exhibits significant quantum confinement effects as well as edge effects, which also leads to its unique electronic and optical properties. Excellent stability and good nonlinear optical absorption characteristics make BPQDs have great research value . Meanwhile, BPQD's size results in a great advantage in a flexible device.…”

“…Excellent stability and good nonlinear optical absorption characteristics make BPQDs have great research value. 123,[128][129][130][131] Meanwhile, BPQD's size results in a great advantage in a flexible device.…”