Study of Ne:He Plasma of a Periodically Pulsed Discharge for Optically Pumped Rare Gas Laser

Optically pumped rare gas lasers (OPRGL) suggested recently as a chemically inert analog of diode-pumped alkali lasers are under extensive study at present. OPRGLs employ metastable atoms of heavier rare gases (Rg*) in He bath produced in discharge plasma. Ar* OPRGL is the most popular system at present, due to presence of a narrow band diode pump and abundance of Ar. However, Ne* OPRGL is interesting due to its visible lasing wavelength at 703.2 nm nm and presence of channels of energy transfer in Ne-He plasma that facilitate Ne* production. We present the first results of experiments with Ne* OPRGL that include Ne* number density in its active medium, and lasing experiments to determine pumping threshold for s5 → p9 transition in a transverse pumping configuration using a narrow band pulsed dye laser as a pump.

All-Fiber Gas Cavity Based on Anti-Resonant Hollow-Core Fibers Fabricated by Splicing with End Caps

In recent years, fiber gas lasers have obtained a rapid development, however, efficient and stable pump coupling is a key limitation for their applications in the future. Here, we report an all-fiber gas cavity based on anti-resonant hollow-core fibers which have the beneficial properties of adjustable broad transmission bands and potential low transmission attenuation, especially in the mid-infrared. This kind of all-fiber gas cavity is fabricated by directly splicing with end caps at both ends for the first time. The high-power laser transmission characteristics were studied, and the experimental results show that the all-fiber gas cavities have a very stable performance. The maximum input laser power at 1080 nm is about 260 W, and the output power is 203 W, giving a total transmission efficiency of 78.1%. This work opens a new opportunity for the development of high-power all-fiber structured fiber gas lasers.

Narrow-Linewidth 2 μm All-Fiber Laser Amplifier with a Highly Stable and Precisely Tunable Wavelength for Gas Molecule Absorption in Photonic Crystal Hollow-Core Fibers

In recent years, mid-infrared fiber lasers based on gas-filled photonic crystal hollow-core fibers (HCFs) have attracted enormous attention. They provide a potential method for the generation of high-power mid-infrared emissions, particularly beyond 4 μm. However, there are high requirements of the pump for wavelength stability, tunability, laser linewidth, etc., due to the narrow absorption linewidth of gases. Here, we present the use of a narrow-linewidth, high-power fiber laser with a highly stable and precisely tunable wavelength at 2 μm for gas absorption. It was a master oscillator power-amplifier (MOPA) structure, consisting of a narrow-linewidth fiber seed and two stages of Thulium-doped fiber amplifiers (TDFAs). The seed wavelength was very stable and was precisely tuned from 1971.4 to 1971.8 nm by temperature. Both stages of the amplifiers were forward-pumping, and a maximum output power of 24.8 W was obtained, with a slope efficiency of about 50.5%. The measured laser linewidth was much narrower than the gas absorption linewidth and the wavelength stability was validated by HBr gas absorption in HCFs. If the seed is replaced, this MOPA laser can provide a versatile pump source for mid-infrared fiber gas lasers.