There is great interest in transition metal-doped InSe because of its high nonlinearity and ultrafast response time at higher light fluence. Herein, Ag-doped InSe nanofilms were precisely manufactured using a direct current-radio frequency sputtering method, and their ultrafast broadband nonlinear optical responses in near-infrared were systematically researched. Ag-doped InSe nanofilm exhibited a broadband nonlinear optical response (800–1100 nm) and ultrafast carrier absorption (<1 ps), and can act as a potential semiconducting material for all-optical devices. Through precise control of the sputtering process parameters, Ag-doped InSe nanofilms were successfully prepared that were smooth, uniform, and exhibited no cracks. Nonlinear optical studies (femtosecond transient absorption spectroscopy and Z-scan measurement) indicated that nonlinear absorption behavior in Ag-doped InSe nanofilm withstands a transformation from saturation absorption to reverse saturation absorption arising from ground state bleaching, free-carrier absorption (FCA), and two-photon absorption (TPA). Additionally, nonlinear refraction behavior in Ag-doped InSe nanofilm was successfully detected near the intrinsic absorption edge, which arose from Kerr refraction and free-carrier refraction. More importantly, the broadband nonlinear response, ultrafast carrier absorption, and carrier recovery time of Ag-doped InSe nanofilm has the ability to controllably tune via Ag doping. Furthermore, Ag-doped InSe nanofilm possesses the nonlinear figure of merit (FOM) of 2.02, which indicates that Ag-doped InSe nanofilm is a promising semiconducting material for all-optical switching devices in near-infrared.

中文翻译：

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银掺杂对多晶Ag掺杂InSe纳米薄膜近红外超快宽带非线性光学响应的​​影响

过渡金属掺杂的 InSe 因其高非线性和在较高光通量下的超快响应时间而引起了极大的兴趣。本文采用直流-射频溅射法精密制备了Ag掺杂InSe纳米薄膜，并系统研究了其在近红外波段的超快宽带非线性光学响应。Ag掺杂的InSe纳米薄膜表现出宽带非线性光学响应（800-1100 nm）和超快载流子吸收（<1 ps），可作为全光学器件的潜在半导体材料。通过精确控制溅射工艺参数，成功制备出光滑、均匀、无裂纹的Ag掺杂InSe纳米薄膜。非线性光学研究（飞秒瞬态吸收光谱和 Z 扫描测量）表明，Ag 掺杂 InSe 纳米薄膜中的非线性吸收行为可承受由基态漂白、自由载流子吸收 (FCA) 和双光子吸收（TPA）。此外，在本征吸收边附近成功检测到 Ag 掺杂 InSe 纳米薄膜的非线性折射行为，这是由克尔折射和自由载流子折射引起的。更重要的是，Ag掺杂InSe纳米薄膜的宽带非线性响应、超快载流子吸收和载流子恢复时间具有可控调谐的能力。在本征吸收边附近成功检测到 Ag 掺杂 InSe 纳米薄膜的非线性折射行为，这是由克尔折射和自由载流子折射引起的。更重要的是，Ag掺杂InSe纳米薄膜的宽带非线性响应、超快载流子吸收和载流子恢复时间具有可控调谐的能力。在本征吸收边附近成功检测到 Ag 掺杂 InSe 纳米薄膜的非线性折射行为，这是由克尔折射和自由载流子折射引起的。更重要的是，Ag掺杂InSe纳米薄膜的宽带非线性响应、超快载流子吸收和载流子恢复时间具有可控调谐的能力。通过Ag 掺杂。此外，Ag掺杂的InSe纳米薄膜具有2.02的非线性品质因数（FOM），这表明Ag掺杂的InSe纳米薄膜是一种很有前途的用于近红外全光开关器件的半导体材料。