Nd:YVO4 Application for High Repetition Frequency Harmonic Self-Mode-Locked Lasers

Abstract

The high repetition rate harmonic mode - locked laser based on an Nd:YVO4 crystal that can achieves a harmonic mode-locked pulse output corresponding to the free spectral range of the gain medium by precisely adjusting the optical length of the resonant cavity.

Nd:YVO4 high repetition rate pulse laser have extensive applications in fields such as high speed optical communications, optical clocks, wireless communications, high - capacity optical networks, quantum communications, and laser ranging.

1064 nm self-mode-locked lasers system

Pump source

The pumping source is an output power of 40 W, with a central wavelength of 808 nm fiber-coupled laser diode. The fiber core diameter is 105 μm, and the numerical aperture is 0.22.

Resonant cavity

The pump beam is focused by a non-spherical lens with a focal length (f) of 28 mm and a coupling efficiency of 85% into the gain medium.

The output mirror (M) is a plane mirror coated with high reflectivity coatings (HR@1064 nm, R=95%, HR@808 nm, R ≥ 99.8%).

Gain medium / F - P cavity

The gain medium is an Nd:YVO4 crystal with a doping concentration (atomic fraction) of 1.0%, a cross-sectional size of 3 mm × 3 mm, and a refractive index of 2.2. The rear end face of the crystal is coated with an anti-reflective coating (AR@808 nm, R ≤ 0.2%) and a high reflectivity coating (HR@1064 nm, R ≥ 99.8%), while the front end face is coated with an anti-reflective coating (AR@808 nm&1064 nm, R ≤ 0.2%). The crystal is wrapped in indium foil 0.1 mm thick to ensure sufficient contact with the heat sink. The heat sink is externally connected to a thermoelectric cooler for temperature control, with a water circulation system for heat dissipation.