Enhanced broadband nonlinear optical response of TiO <sub>2</sub> /CuO nanosheets via oxygen vacancy engineering
Dong Li, Hongwei Chu, Xiao Wang, Ying Li, Shengzhi Zhao, Dechun Li
Abstract
Abstract Cupric oxide (CuO), as a transition metal oxide (TMO) semiconductor, has attracted tremendous attention for various applications. In the present work, we synthesize the CuO nanosheets modified by TiO 2 nanoparticles via a facile, non‐toxic two‐step method. Subsequently, the morphology and the structures of CuO and TiO 2 /CuO nanocomposites are investigated. By utilizing the common Z‐scan technology, broadband nonlinear optical (NLO) properties of the as‐prepared CuO nanosheets and TiO 2 /CuO nanocomposites are demonstrated, elucidating the enhancement on the NLO response via the TiO 2 dopant, which is attributed to the more oxygen vacancies and the formed p‐n junctions. Furthermore, CuO nanosheets and TiO 2 /CuO nanocomposites are implemented to the passively Q‐switched bulk lasers operating in the near‐infrared (NIR) region, generating broadband ultrastable pulses. Ultimately, TiO 2 /CuO nanocomposites were intergrated in a passive mode‐locking bulk laser for the first time, achieving stable mode‐locked pulses and verifying its ultrafast optical response potential. Our results illustrate the tremendous prospects of the CuO nanosheets modified by oxygen vacancy engineering as a broadband NLO material in ultrafast photonics field.