Mid-Infrared Laser Emissions of Tm3+-doped Garnets: The Case Study of Disordered Tm:CNGG Crystal

Recently, disordered garnets such as CNGG (calcium niobium gallium garnet) doped with Tm 3+ and codoped with Tm 3+ and Ho 3+ ions have attracted a lot of attention for generation of ultrashort pulses at ~2 µm [1] . Pan et al . reported on a Tm oscillator operating on the 3 F 4 → 3 H 6 transition and delivering 84 fs pulses at 2018 nm (emission bandwidth: >50 nm) and demonstrated continuous wavelength tuning between 1879-2086 nm [1] . It is interesting to extend the emission range of such crystals further into mid-IR. It can be done by exploiting either (i) vibronic emissions relying on electron-phonon-coupling or (ii) less common electronic 3 H 4 → 3 H 5 transition [2] .