ABSTRACT
We report on a powerful mid-IR diode-side-pumped tunable Er:LiYF4 (Er:YLF) laser electro-optically Q-switched with the help of a KTiOPO4 crystal. At a 20 Hz repetition rate, the laser pulses with output energy of 82 mJ and 13 ns duration at the wavelength of 2.67 µm are obtained. At higher repetition rates (up to 50 Hz), one can extract up to 20 mJ from the laser cavity. The developed mid-IR laser source demonstrates high peak (up to 6.3 MW) and average (up to 1.7 W) power. Realized wavelength tuning provides access for megawatt-peak power-level nanosecond laser pulses over the 2667-2851 nm wavelength region, which are highly demanded for mid-IR laser systems development and light-matter interaction study in the view of extreme-state creation in liquids and solids, paving the way to novel microprocessing techniques.
ABSTRACT
We report, for the first time, to the best of our knowledge, a femtosecond mode-locked Fe:ZnSe laser. Passive mode locking is implemented using graphene as a saturable absorber. The laser operates at 4.4 µm with a repetition frequency of 100 MHz and 415 mW output power pumped by a fiber 7 W Er:ZBLAN laser. The pulse duration of about 732 fs is retrieved from the first-order autocorrelation function. Additionally, we observe pulsed nanosecond oscillation under continuous-wave pumping and strong amplitude modulation caused by Kerr self-focusing. This Letter fills the gap in operating regimes of Fe:ZnSe lasers and paves the way for the development of powerful ultrafast high-repetition-rate mid-IR sources for the most advanced fields of science.
ABSTRACT
We report, to the best of our knowledge, the first use of KY(WO4)2 and KG(WO4) acousto-optical Q-switches in 3-µm powerful lasers. Q-switches of two different designs (normal incidence with antireflection coatings, and Brewster-angle cut crystals) operate in lasers based on Er:YAG, Cr:Yb:Ho:YSGG, and Cr:Er:YSGG laser crystals. Gain and lifetime of laser crystals significantly influence the regime of Q-switched generation. Er:YAG and Cr:Yb:Ho:YSGG lasers deliver pulses with 10.8 mJ and 17.5 mJ energy, respectively. Pulses with energy of 29.6 mJ and duration of 75 ns in the TEM00 mode are obtained in a Cr:Er:YSGG laser. The energy is scaled up to 85.7 mJ in the two-stage master oscillator power amplifier system. Powerful laser systems of this kind are in the region of interest for pumping other mid-IR laser media (e.g., Fe:ZnSe and Fe:CdSe), OPOs, CO2 lasers, and amplifiers. Preliminary experiments on microstructuring of transparent materials by the laser-induced backside wet etching method demonstrate the potential of such lasers to build the foundation for dye-free tissue and cell engineering concepts.
ABSTRACT
In this Letter, we report a compact and robust coherent source, operating in mid-infrared (IR) and based on the Fe:ZnSe chalcogenide gain medium, optically pumped by an Er:ZBLAN fiber laser. The output power of 2.1 W with a 59% slope efficiency with respect to the absorbed pump power at liquid nitrogen cooling is achieved. We show that strong re-absorption at a high pump power and iron ion doping concentrations leads to a continuous tuning of central wavelength from 4012 to 4198 nm. The robustness of a high-power Er:ZBLAN fiber laser combined with prominent spectroscopic properties of Fe:ZnSe media pave the way for the development of a reliable tunable continuous-wave mid-IR sources for scientific and industrial purposes.
ABSTRACT
We have developed a robust optical parametric amplifier (OPA) based on three-AgGaS2-crystal pumping by a Cr:Forsterite GW femtosecond laser system, generating 150 fs pulses in dual bands of 1.6-2.0 µm (signal wave) and 3.5-5.5 µm (idler wave). By introducing a negative prechirp to the pump, a combined efficiency in two waves of greater than 10% was achieved, with signal energy up to 110 µJ and idler energy up to 43 µJ. Operation parameters of the system (intensity up to 90 TW/cm2) make OPA a promising tool for driving nonlinear optical phenomena, including generation of optical harmonics and laser-induced extreme states of matter in solids and liquids. As a proof of principle, we generated harmonics up to the sixth order and sum frequencies in 5 mm thick polycrystalline ZnSe.
