Mo:BiVO₄ Nanoparticles-Based Optical Modulator and Its Application in a 2-μm Pulsed Laser

Area of Science:

• Materials Science
• Laser Physics
• Nonlinear Optics

Background:

• All-solid-state lasers operating in the 2-μm wavelength region are crucial for various applications, including medical diagnostics and remote sensing.
• Developing efficient and cost-effective optical modulators is essential for optimizing the performance of these lasers.
• Molybdenum-doped Bismuth Vanadate (Mo:BiVO4) is a material with potential nonlinear optical properties.

Purpose of the Study:

• To investigate the feasibility of using Mo:BiVO4 nanoparticles as a saturable absorber for Q-switched all-solid-state Tm:YAP lasers.
• To characterize the nonlinear optical parameters of Mo:BiVO4 nanoparticles in the 2-μm spectral region.
• To evaluate the performance of a laser incorporating Mo:BiVO4 nanoparticles as an optical modulator.

Main Methods:

• Synthesis and characterization of Mo:BiVO4 nanoparticles.
• Nonlinear transmission measurements to determine optical parameters.
• Integration of Mo:BiVO4 nanoparticles into a Q-switched Tm:YAP laser cavity.
• Analysis of laser output characteristics, including repetition rate, pulse width, and output power.

Main Results:

• Mo:BiVO4 nanoparticles exhibited saturable absorption at 2 μm, with a saturation intensity of 718 MW/cm² and a modulation depth of 12.3%.
• Stable Q-switched operation was achieved with a maximum repetition rate of 70.08 kHz and a pulse width of 821 ns.
• The laser produced a maximum output average power of 153 mW, with a single pulse energy of 2.18 μJ and peak power of 2.67 W.
• Sub-bandgap absorption was identified as the mechanism responsible for the saturable absorption effect at 2 μm, despite the material's visible light response.

Conclusions:

• Mo:BiVO4 nanoparticles demonstrate significant potential as an effective optical modulator for 2-μm pulsed lasers.
• The observed sub-bandgap absorption highlights the versatility of Mo:BiVO4 nanoparticles for infrared applications.
• This study experimentally validates Mo:BiVO4 nanoparticles as a promising candidate for advanced laser modulation technologies.