Mid-infrared tunable optical parametric oscillator pumped by a Q -switched Tm,Ho:YAG ceramic laser

Abstract

Since resonant absorption of light caused by a variety of different molecular bond occurs in the mid-infrared (MIR) wavelength region, many applications using tunable MIR lasers have been reported. However, the applicable fields of the MIR tunable lasers have been restricted by their large size and high cost equipments. Therefore, we are developing a compact tunable MIR laser using an optical parametric oscillator (OPO). To obtain a long term stability and a high conversion efficiency, a diode-pumped and Q-switched Tm,Ho:YAG ceramic laser with a wavelength of 2.1 µm was adopted for the pump source. A maximum output energy of 40 mJ was obtained with the Tm,Ho:YAG ceramic laser at a pulse width of 150 ns and a repetition rate of 10 Hz. An experiment was performed using a singly-resonant OPO with a ZnGeP 2 crystal pumped by another OPO with a wavelength of 2.1 µm. A threshold pump fluence of 0.2 J/cm 2 and a slope efficiency of 60% were obtained at a signal and idler wavelengths of 3.3 and 5.6 µm, respectively. Using these results and a theoretical model calculation, the maximum output energy of MIR-OPO pumped with the Tm,Ho:YAG ceramic laser was estimated to be about 20 mJ.

High-Power Dual-End-Pumped Actively Q-Switched Ho:YAG Ceramic Laser

“…The maximum pulse energy of 40 mJ with a pulse width of 150 ns at a pulse repetition frequency (PRF) of 10 Hz was achieved from a diode-pumped Tm,Ho:YAG ceramic laser. [10] Furthermore, the maximum cw output power of 2.5 W and a slope efficiency of 35% with respect to the absorbed pump power were demonstrated with a Ho:Y 2 O 3 ceramic laser. [11] In another study, [12] the maximum output power of 21.4 W at 2097 nm with a slope efficiency of 63.6% was obtained at the incident pump power of 35 W. Moreover, the maximum pulse energy of 10.2 mJ and the maximum average output power of 1.9 W were achieved from an acousto-optical Q-switched Ho:YAG ceramic laser, the corresponding PRFs were 100 Hz and 200 Hz, respectively.…”

Development of a mid-infrared tunable optical parametric oscillator pumped by a Q-switched Tm,Ho:YAG laser

“…Figure 1 shows the configuration of an OPO pumped by a Tm,Ho:YAG ceramic laser used in this research. The diodepumped and Q-switched Tm,Ho:YAG laser consisted of a flat rear mirror (high reflector), a pumping chamber, an acousto-optic Q-switch (Model MT3205P, MolTech GmbH, Berlin, Germany), and a flat output coupler with a reflectance of 75% at the wavelength of 2.09 µm 21 . A YAG ceramic rod with a diameter of 4 mm and a length of 68 mm had undoped regions with a length of 22 mm for both sides of a doped region with a length of 24 mm, and both ends of the rod was cut at the Brewster's angle.…”

Ho:YAG ceramic laser pumped by Tm:YLF lasers at room temperature

“…Moreover, passively Q-switching and mode-locking ceramic lasers have also been reported recently [21,22]. As the development of ceramic sintering technology, transparent ceramic with low scattering loss at 2 μm waveband can [23,24].…”