Titanium Dioxide Langmuir–Blodgett Film Saturable Absorber for Passively Q-switched Nd:GdVO₄ Laser

Abstract

A high-transmittance ultra-thin titanium dioxide (TiO2) film saturable absorber (SA) fabricated by Langmuir-Blodgett (LB) technology is reported and used for the first time to obtain passively Q-switched pulses from a solid-state laser. The optical loss of pure TiO2 LB film at a wavelength of 1 μm is only 6.5%, and the nonlinear modulation depth, saturation intensity, and non-saturable loss of the entire TiO2 SA device are 4.3%, 0.125 MW/cm2, and 9.8%, respectively. Intrinsic high stability and heat resistance of TiO2 nanomaterials contribute to a laser output with average power (2.35 W) and a corresponding laser pulse width and repetition rate of 173 ns and 2.008 MHz, respectively. The laser output with the pulse energy of 1.17 μJ and peak power of 6.76 W indicates the excellent potential of TiO2 nanomaterials for applications in solid-state pulsed lasers.

Keywords

• Q-switched laser
• saturable absorber
• solid-state laser
• nonlinear optical materials.