Here, attenuation loss effect and laser performance enhancement of Nd:YAG transparent ceramics were investigated. Using a 0.6 at.% Nd:YAG ceramic rod with 3 mm diameter and 65 mm length, the scattering coefficient and absorption coefficient at 1064 nm were measured to be 0.0001 cm-1 and 0.0017 cm-1 , respectively. For the 808 nm side-pumped laser experiment, an average output power of 44.9 W was achieved with an optical-to-optical conversion efficiency of 26.4%, which was nearly same with that of 1 at.% single crystal. Adopting the 885 nm direct end-pumped scheme, the following laser tests demonstrated the high optical efficiency of 62.5% and maximum output power of 144.8 W were obtained at absorbed pump power of 231.5 W. This was up to now the highest optical conversion efficiency acquired in Nd:YAG ceramic laser to our knowledge. It proves that high power and high efficiency laser output could be generated by high optical quality Nd:YAG ceramic rod along with the 885 nm direct pumping technology.
This paper presents a high pulse energy, narrow linewidth, mid-infrared (MIR) laserat 6.45 µm, based on a BaGa4Se7 (BGSe) crystal optical parametric oscillator (OPO) pumped by1.064 µm laser. The maximum pulse energy at 6.45 µm was up to 1.23 mJ, with a pulse width of 24.3 ns and repetition rate of 10 Hz, corresponding to an optical–optical conversion effificiency of 2.1%, from pump light 1.064 µm to idler light 6.45 µm. The idler light linewidth was about 6.8 nm.Meanwhile, we accurately calculated the OPO phase-matching condition at BGSe crystal pumped by 1.064 µm laser, and a numerical simulation system was performed to analyze the input–outputcharacteristics at 6.45 µm, as well as the effect of crystal length on the conversion effificiency. Good agreement was found between measurement and simulation. To the best of our knowledge, this is the highest pulse energy at 6.45 µm, with the narrowest linewidth for any all-solid-state MIR ns laser in BGSe-OPO pumped by simple 1.064 µm oscillator. This simple and compact 6.45 µm OPO system, with high pulse energy and narrow linewidth, can meet the requirements for tissue cutting and improve tissue ablation accuracy.
In this paper, we demonstrate a langasite (LGS) electro-optic Ho:YAG cavity-dumped laser that suppresses the gain dependence of pulse duration in Q-switched lasers. A constant pulse duration of 7.2 ns was achieved at a repetition rate of 100 kHz. Benefiting from the LGS crystal has no significant reverse piezoelectric ring effect and thermally induced depolarization, a stable pulse train was achieved at an output power of 43 W. For the first time, the application of cavity-dumped laser in mid-infrared (mid-IR) ZnGeP2 (ZGP) optical parametric oscillator (OPO) has been realized, providing a reliable way to achieve high repetition rates and short nanosecond pulse times for high-power mid-infrared ZGP OPOs. The average output power was 15 W, corresponding to a pulse duration of 4.9 ns and a repetition rate of 100 kHz.
We demonstrate for the first time the generation of octave-spanning mid-infrared using a BGSe nonlinear crystal. A Cr:ZnS laser system delivering 28-fs pulses at a central wavelength of 2.4 µm is used as the pump source, which drives the intra-pulse difference frequency generation inside the BGSe crystal. As a result, a coherent broadband mid-infrared continuum spanning from 6 to 18 µm has been obtained. It shows that the BGSe crystal is a promising material for broadband, few-cycle mid-infrared generation via frequency down conversion with femtosecond pump sources.
1.53 W all-solid-state nanosecond pulsed mid-infrared laser at 6.45 µm
