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We report on mode-locking of an Yb:Ca 3 NbGa 3 Si 2 O 14 laser, which is pumped by a fiber-coupled single-mode laser diode. The shortest pulse duration obtained with a semiconductor saturable absorber mirror is 52 fs, with 75 mW of average output power. Sub-60 fs operation tunable between 1055 and 1074 nm is achieved by employing semiconductor absorbers with different characteristics. We also demonstrate passive mode-locking results with transmissive graphene saturable absorber, reaching an 85 fs pulse duration with 23 mW output power. Moreover, we present the non-phase-matched self-frequency doubling properties of this non-centrosymmetric crystal in the femtosecond regime.

Trigonal langasite-type ordered silicate crystal Yb : Ca 3 Nb Ga 3 Si 2 O 14 (Yb:CNGS) is a promising material for efficient ∼1   μm lasers. We report on the first passively Q -switched Yb:CNGS laser using Cr 4+ : YAG and V 3+ : YAG saturable absorbers (SAs) with a 976 nm volume-Bragg-grating-stabilized diode as a pump source. The laser crystal was a c cut 3 at.% Yb:CNGS grown by the Czochralski method. It was placed in a compact microchip-type laser cavity. With a Cr 4+ : YAG SA, very stable 62.2 μJ/4.4 ns pulses were achieved at a repetition rate of 22.5 kHz. The average output power was 1.40 W at 1015.3 nm, corresponding to a Q switching conversion efficiency of 90%. With the V 3+ : YAG SA, the pulse characteristics were 13.3 μJ/11.1 ns at a higher repetition rate of 68.4 kHz. The performance of the Yb : CNGS / Cr 4+ : YAG was numerically modeled showing a good agreement with the experiment.

The laser properties of Nd:YPO 4 crystal were demonstrated for the first time. For a 1.2 at.% doped Nd:YPO 4 crystal, the absorption cross-section at 803 nm, stimulated emission cross-section at 1063 nm, and fluorescence lifetime was measured to be 8.1 × 10 -20 cm 2 , 1.6 × 10 -19 cm 2 , 156 μs, respectively. With an as-grown 0.6 mm thin slice which was unpolished and uncoated, efficient diode-pumped continue-wave (CW) laser operations were realized at 1.06 and 1.3 μm wavebands. The 1063 nm output power reached 2.16 W when the absorbed pump power was 4.07 W, corresponding to an optical-to-optical efficiency of 53%, and a slope efficiency of 56.4%. The 1.3 μm laser output exhibited the simultaneous operations of dual-wavelengths, i.e. 1338 and 1347 nm. The maximum output power was 800 mW at an absorbed pump power of 3.08 W, giving an optical-to-optical efficiency of 26% and a slope efficiency of 28.2%.

We report on, to the best of our knowledge, the first sub-100 fs mode-locked Ho 3+ -laser in the 2 μm spectral range employing a disordered co-doped Tm,Ho:CaYAlO 4 (Tm,Ho:CALYO) crystal as a gain medium. Pulses as short as 87 fs are produced with an average output power of 27 mW at 80.45 MHz repetition rate. An output power of 96 mW is reached for a pulse duration of 98 fs.

With Cr 4+ :YAG as a saturable absorber, a passively Q-switched self-frequency-doubled (SFD) laser based on a trigonal Nd:Ca 3 NbGa 3 Si 2 O 14 (Nd:CNGS) silicate crystal was demonstrated for the first time. The maximum average output power at 532 nm was 16.2 mW, and the corresponding pulse repetition frequency, single pulse energy, pulse duration and peak power were 2.25 kHz, 7.2 μJ, 13.7 ns, 0.53 kW, respectively. We also present a rate-equation model of such a passively Q-switched SFD laser showing a good agreement with the experiment. Nd:CNGS is a promising pulse SFD material for miniature all-solid-state visible light sources.

Multi-watt continuous-wave (CW) operation of tetragonal rare-earth calcium aluminate Yb:CaLnAlO 4 (Ln=Gd,Y)) crystals in plano-plano microchip lasers was demonstrated with an almost quantum-defect-limited slope efficiency. Pumped at 978 nm by an InGaAs laser diode, a 3.4 mm long 8 at. % Yb:CaGdAlO 4 laser generated 7.79 W at 1057-1065 nm with a slope efficiency of η=84% (with respect to the absorbed pump power). An even higher η=91% was achieved with a 2.5 mm long 3 at. % Yb:CaYAlO 4 laser, from which 5.06 W were extracted at 1048-1056 nm. Both lasers produced linearly polarized output (σ-polarization) with an almost circular diffraction-limited beam (Mx,y2<1.1). The output performance of the developed lasers was modeled, yielding an internal loss coefficient as low as 0.004-0.007  cm -1 . In addition, their spectroscopic properties were revisited.