200 kHz 5.5 W Yb(3+): YVO4-based chirped-pulse regenerative amplifier.

A chirped-pulse regenerative amplifier based on a Yb:YVO4 (Yb:YVO) crystal was demonstrated for the first time, to our knowledge. A novel wavelength-independent off-axis technique was used to deliver 26.6 W of pump power with a low quantum defect. It was seeded by means of a 120 fs Yb:YVO4 oscillator. It generates as much as 5.5 W of average output power with chirped pulses and 4.2 W with 200 fs compressed pulses at a 200 kHz repetition rate. A maximum pulse energy of 140 µJ was obtained at pulse repetition frequencies up to 25 kHz at the central wavelength of 1018 nm.

Dispersion and anisotropy of thermo-optic coefficients in tetragonal GdVO4 and YVO4 laser host crystals.

A detailed experimental study of dispersion and anisotropy of thermo-optic coefficients dn/dT and thermal coefficients of the optical path W=dn/dT+(n-1)α is performed for tetragonal YVO(4) and GdVO(4) laser host crystals by a laser beam deviation method. It is supported by theoretical description of thermo-optic effects, taking into account the volumetric thermal expansion effect and the temperature dependence of electronic bandgap E(g). Linear thermal expansion coefficients α were also determined by a dilatometric technique. Thermo-optic dispersion formulas describing temperature variation of the refractive index and the thermal lens effect are derived for a wide spectral range of 0.4-2 µm. It allows us to estimate the values of E(g) and dE(g)/dT for the studied crystals. The influence of materials parameters and pumping conditions on thermal lens properties is discussed, revealing the significant impact of anisotropic and temperature-dependent thermal conductivity.

In-band fiber-laser-pumped Er:YVO4 laser emitting around 1.6 µm.

Efficient laser operation at wavelengths around 1.6 µm is demonstrated in Er (1.1 at. %):YVO4. The crystal is in-band pumped at 1536 nm by a fiber laser, resulting in a maximum slope efficiency of 57.9% with respect to the absorbed pump power and 2.3 W of maximum output power. Wavelength tuning with a birefringent filter to wavelength bands suitable for CO2 lidar applications at 1579 and 1603 nm could be obtained.