90-fs diode-pumped Yb:CLNGG laser mode-locked using single-walled carbon nanotube saturable absorber

Spectroscopy and 2.8 µm laser operation of disordered Er:CLNGG crystals

We report on the first, to the best of our knowledge, laser operation on the ⁴I_11/2 → ⁴I_13/2 transition of erbium-doped disordered calcium lithium niobium gallium garnet (CLNGG) crystals with broadband mid-infrared emission properties. A 41.4 at.% Er:CLNGG continuous-wave laser generated 292 mW at 2.80 µm with 23.3% slope efficiency and a laser threshold of 209 mW. Er³⁺ ions in CLNGG feature inhomogeneously broadened spectral bands (σ_SE = 1.79 × 10^-21 cm² at 2.79 µm; emission bandwidth, 27.5 nm), a large luminescence branching ratio for the ⁴I_11/2 → ⁴I_13/2 transition of 17.9%, and a favorable ratio of the ⁴I_11/2 and ⁴I_13/2 lifetimes, exhibiting values of 0.34 ms and 1.17 ms (for 41.4 at.% Er³⁺), respectively.

Kerr-lens mode-locking of an Yb:CLNGG laser

We report on a Kerr-lens mode-locked laser based on an Yb³⁺-doped disordered calcium lithium niobium gallium garnet (Yb:CLNGG) crystal. Pumping by a spatially single-mode Yb fiber laser at 976 nm, the Yb:CLNGG laser delivers soliton pulses as short as 31 fs at 1056.8 nm with an average output power of 66 mW and a pulse repetition rate of ∼77.6 MHz via soft-aperture Kerr-lens mode-locking. The maximum output power of the Kerr-lens mode-locked laser amounted to 203 mW for slightly longer pulses of 37 fs at an absorbed pump power of 0.74 W, which corresponds to a peak power of 62.2 kW and an optical efficiency of 20.3%.

Sub-100 fs mode-locked Tm:CLTGG laser

We report on the first sub-100 fs mode-locked laser operation of a Tm³⁺-doped disordered calcium lithium tantalum gallium garnet (Tm:CLTGG) crystal. Soliton mode-locking was initiated and stabilized by a transmission-type single-walled carbon nanotube saturable absorber. Pulses as short as 69 fs were achieved at a central wavelength of 2010.4 nm with an average power of 28 mW at a pulse repetition rate of ∼87.7 MHz. In the sub-100 fs regime, the maximum average output power amounted to 103 mW.