Arkady Major

A continuous-wave (CW), high-power, quasi-three-level Nd:YAG laser operating at 946 nm is reported. The beam quality of the laser is greatly improved. The laser consists of a composite Nd:YAG rod end pumped by a fiber-coupled diode laser inside a simple concave-plane cavity. At an incident pump power of 31 W, a maximum CW output of 9.98 W was obtained at 946 nm, with a beam quality factor of M²~5. The corresponding optical-to-optical efficiency was 32.2% with respect to the incident pump power. To the best of our knowledge, this is the highest output power at 946 nm with such a beam quality ever generated by diode-pumped Nd:YAG laser with bulk crystals.

Dispersion and anisotropy of thermal coefficients of the optical path (TCOP) and thermo-optic coefficients (TOCs) of Alexandrite laser crystal (Cr³⁺:BeAl₂O₄) are studied for the three principal light polarizations, E || a, E || b and E || c. Thermo-optic dispersion formulas are presented for the spectral range of 0.4-1.1 µm. All TOCs are positive and show a notable polarization-anisotropy, dn_a/dT = 5.9, dn_b/dT = 6.9 and dn_c/dT = 15.2 × 10⁻⁶ K⁻¹ at 0.75 µm. Thermal lensing was characterized in a continuous-wave Alexandrite laser pumped at 0.532 µm and operating at 0.7509 µm (for E || b). The measured thermal lens was weak, positive and slightly astigmatic. The sensitivity factors of the thermal lens were found to be M_x = 1.74 and M_y = 2.38 [m⁻¹/W].

A high-power sub-50 fs diode-pumped Yb:CALGO laser oscillator is demonstrated. The peak power achieved for 45 fs pulses directly from the oscillator was 1.7 MW. To the best of our knowledge, this is the highest peak power in the sub-50 fs pulse regime that has ever been produced directly from any diode-pumped Yb-ion-doped laser oscillator to date. The shortest generated pulses were 38 fs long with 187 kW of peak power.

An Alexandrite laser passively mode-locked using an InP/InGaP quantum-dot semiconductor saturable absorber mirror (QD-SESAM) was demonstrated. The laser was pumped at 532 nm and generated pulses as short as 380 fs at 775 nm with an average output power of 295 mW. To the best of our knowledge, this is the first report on a passively mode-locked femtosecond Alexandrite laser using a SESAM in general and a QD-SESAM in particular.

We report on the first semiconductor saturable absorber mirror mode-locked Nd:GdVO ₄ laser directly diode-pumped at 912 nm. The laser generated 10.14 W of averaged output power at 1063 nm with the pulse width of 16 ps at the repetition rate of 85.2 MHz. The optical-to-optical efficiency and slope efficiency in the mode-locked regime were calculated to be 49.6% and 67.4% with respect to the absorbed pump power, respectively. Due to the low quantum defect pumping the output power was limited only by the available pump power.