Near‐Infrared All‐Optical Switching Based on Nano/Micro Optical Structures in YVO4 Matrix: Embedded Plasmonic Nanoparticles and Laser‐Written Waveguides

Nonlinear interactions between light and matter give rise to a wide range of applications for both fundamental and applied research. Herein, near‐infrared switching of the optical response based on embedded Ag nanoparticles and laser‐written optical waveguides within yttrium vanadate (YVO4) crystal matrix is demonstrated. Using broadband transient absorption spectroscopy with a combination of femtosecond Z‐scan spectroscopy, the plasmon‐enhanced features of the third‐order optical nonlinearity in Ag:YVO4 nanocomposite at the near‐infrared band are elucidated. Meanwhile, an optical‐lattice‐like microscale waveguide is fabricated with well‐preserved photoluminescence properties by femtosecond laser writing. Taking advantage of the ultrafast on–off switching behavior of Ag:YVO4 saturable absorber, a Q‐switched pulsed laser operation in the waveguide platform, delivering 1 μm light pulses with high peak power of 298 mW, is demonstrated. This work indicates a possible path for the development of chip‐scale ultrafast photonic devices.