Optical spectroscopy and efficient continuous-wave operation near 2 μm for a Tm, Ho:KYW laser crystal

Microchip laser operation of Tm,Ho:KLu(WO_4)_2 crystal

“…The beam quality factor M 2 for the Tm,Ho:KLuW microchip laser was below 1.1. The reported results for the diode-pumped Tm,Ho:KLuW microchip laser are superior compared to all previous demonstrations with diode-pumped Tm,Ho-codoped YAP [15], YVO 4 or GdVO 4 [17,18], both in terms of output power and slope efficiency. In comparison with the state-of-the-art for Tm,Ho:YLF [13], we achieved 1.5-times increase of the output power.…”

“…Tm,Ho codoping of a laser host material brings the feature of enhanced pump efficiency and the possibility to increase the output power because the strong absorption of Tm ions in the range of 795-802 nm matches the output of AlGaAs laser diodes and subsequent energy transfer, 3 F 4 (Tm)→ 5 I 7 (Ho) results in the excitation of the upper laser level of Ho. In recent years, several hosts were studied for Tm,Ho codoping, like LiYF 4 (YLF), YAlO 3 (YAP), YVO 4 , GdVO 4 , etc., and efficient lasers were realized with such gain materials. The above mentioned applications require high pump power and high efficiency at 2 μm, attainable only by means of high power diode pumping of the active medium.…”

“…In recent years, a substantial progress was achieved in the field of Tm,Ho:DT lasers. Lagatsky et al demonstrated continuous-wave (CW) laser operation of Ho in the isostructural Tm,Ho:KYW laser crystal pumping with a Ti:Sapphire laser and achieving 460 mW of output power [4]. Later on, this work was extended to ultrashort pulse generation in picosecond [5] and femtosecond [6] regimes achieving pulses of 570 fs duration at a wavelength of 2055 nm.…”

High repetition rate, Q-switched Ho:YAG laser resonantly pumped by a 20 W linearly polarized Tm: fiber laser

“…and holmium (Ho 3? ) co-doped materials [8,9], diode-pumped thulium-doped bulk [10] and fiber lasers [11], holmium lasers pumped by diodepumped thulium lasers [12,13], and hybrid-type lasers [14] are commonly used. It is worth mentioning that supercontinuum (SC) fiber-based generators have also been treated as an attractive source of mid-infrared radiation [15], especially as they can provide over an octave-spanning spectrum of output laser beam with only diffractionlimited quality.…”

Broadly tunable femtosecond mode-locking in a Tm:KYW laser near 2 μm

“…Recently, we have reported the generation of 570-fs pulses from a passively mode-locked Tm,Ho:KY(WO 4 ) 2 laser [13] and pulses as short as 191 fs were produced from Tm,Ho:NaY(WO 4 ) 2 [14], both operating around 2060 nm. It must be recognized though, that Tm-Ho codoped materials can suffer from the presence of increased up-conversion processes [15] compared to single Tmdoping and this in turn can lead to additional thermal loading inside the gain medium, resulting in reduced laser efficiency and limited output powers during continuous wave operation at room temperature. For this reason, direct generation of ultrashort pulses from Tm-doped materials looks more attractive for further development of laser diode pumped high-power mode-locked lasers that operate around 2 μm.…”