TY - JOUR

T1 - Remarkable enhancement of the nonlinear optical absorption of W18O49 by Cu doping

AU - He, Miao

AU - Boukhvalov, Danil

AU - Li, Hui

AU - Gao, Xiangyun

AU - Humphrey, Mark

AU - Zhang, Chi

AU - Huang, Zhipeng

N1 - Z. Huang acknowledges the support from the National Natural Science Foundation of China ( 62275197 and 51772214 ), the Natural Science Foundation of Shanghai ( 23ZR1465700 ), the Fundamental Research Funds for the Central University , and the National Youth Talent Support program of China ( W03070073 ). M. G. Humphrey thanks the Australian Research Council ( DP170100411 ). C. Zhang acknowledges support from the National Natural Science Foundation of China ( 51432006 ), the Ministry of Education of China ( IRT14R23 ), the 111 Project ( B13025 ), and the Innovation Program of Shanghai Municipal Education Commission . DWB acknowledges research funding from Jiangsu Innovative and Entrepreneurial Talents Project.

PY - 2024

Y1 - 2024

N2 - Advanced nonlinear optical (NLO) materials, such as metal chalcogenides, black phosphorus, and perovskites, have encountered challenges arising from their inherent low chemical and thermal stability. The desirable attributes of chemical and thermal stability are exhibited by promising metal oxides within NLO applications, whereas the NLO response of metal oxides has typically shown modest strength. In this study, we report the striking enhancement of NLO absorption in W18O49 achieved through the introduction of defects via Cu doping. Following a 4-hour doping treatment, the nonlinear absorption coefficients (βeff) of Cu-doped W18O49 exhibit remarkable values of (3.36 ± 0.11) × 103 cm GW−1 and (5.76 ± 0.33) × 103 cm GW−1 upon laser excitation at 515 and 800 nm, respectively. These values are approximately 10 and 32 times higher than those measured in the pristine samples. This performance surpasses that of various other metal oxides and stands on par with the optimal tungsten/molybdenum-based chalcogenide counterparts. Notably, our investigation reveals a direct correlation between higher levels of Cu doping and an augmented βeff. Our investigations using X-ray photoelectron spectroscopy, Raman spectroscopy, ultraviolet photoelectron spectroscopy, electron paramagnetic resonance, and density functional theory calculations reveal that Cu doping induces the creation of oxygen vacancies, precipitating a concurrent reduction in bandgap and the emergence of in-gap defect states. Transient transmittance difference spectra highlight the effective role played by in-gap defect states as excitation pathways. Consequently, a greater abundance of these in-gap states corresponds to heightened optical nonlinearity. © 2024 Elsevier Ltd.

AB - Advanced nonlinear optical (NLO) materials, such as metal chalcogenides, black phosphorus, and perovskites, have encountered challenges arising from their inherent low chemical and thermal stability. The desirable attributes of chemical and thermal stability are exhibited by promising metal oxides within NLO applications, whereas the NLO response of metal oxides has typically shown modest strength. In this study, we report the striking enhancement of NLO absorption in W18O49 achieved through the introduction of defects via Cu doping. Following a 4-hour doping treatment, the nonlinear absorption coefficients (βeff) of Cu-doped W18O49 exhibit remarkable values of (3.36 ± 0.11) × 103 cm GW−1 and (5.76 ± 0.33) × 103 cm GW−1 upon laser excitation at 515 and 800 nm, respectively. These values are approximately 10 and 32 times higher than those measured in the pristine samples. This performance surpasses that of various other metal oxides and stands on par with the optimal tungsten/molybdenum-based chalcogenide counterparts. Notably, our investigation reveals a direct correlation between higher levels of Cu doping and an augmented βeff. Our investigations using X-ray photoelectron spectroscopy, Raman spectroscopy, ultraviolet photoelectron spectroscopy, electron paramagnetic resonance, and density functional theory calculations reveal that Cu doping induces the creation of oxygen vacancies, precipitating a concurrent reduction in bandgap and the emergence of in-gap defect states. Transient transmittance difference spectra highlight the effective role played by in-gap defect states as excitation pathways. Consequently, a greater abundance of these in-gap states corresponds to heightened optical nonlinearity. © 2024 Elsevier Ltd.

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U2 - 10.1016/j.mtphys.2024.101357

DO - 10.1016/j.mtphys.2024.101357

M3 - Article

VL - 42

JO - Materials Today Physics

JF - Materials Today Physics

SN - 2542-5293

M1 - 101357

ER -