High-power 47.6 and 57.2 μm CH3OD lasers pumped by continuous-wave 9R(8) CO2 laser

Abstract

Powerful lasers in the far-infrared wavelength range (47.6 and 57.2 μm) have been developed to measure the plasma density in the Large Helical Device at National Institute for Fusion Science and future plasma devices such as the International Thermonuclear Experimental Reactor. The intensification of these lasers has been done by cooling the laser tube wall, adding He as the buffer gas, and using a chemical-vapor-deposited diamond output window. The output powers for the 57.2 and 47.6 μm lasers have been found to be 1.6 and 0.8 W, respectively.

A polarization modulator for the far infrared (terhahertz waves)

“…4 To that end, they have designed and built lasers that operate at 47.6 and 57.2 m. The lasers are pumped by CO 2 lasers and use CH 3 OD molecules as the active material. 5 Akiyama and others are developing an interferometer /Stokes polarimeter system using the 47.6 and 57.2 m laser beams for measuring electron density and current profiles in plasma. 6 The instrument will be used in magnetically confined fusion devices, initially the Large Helical Device (LHD) in Japan.…”

Progress in development of two color laser diagnostics for the ITER poloidal polarimeter

“…Therefore, we have been developing shorter wavelength laser oscillation lines, and achieved a lot of high power oscillation lines between 40 µm and 100 µm [3]. Among them, the most powerful oscillation line is a 57.2 µm CH 3 OD laser line pumped by a continuous wave 9R(8) CO 2 laser, which simultaneously oscillates with a 47.7 µm line [4]. These two color laser oscillation lines enable us to develop a two color laser interferometer/polarimeter.…”

Two-Color Laser Interferometer using 48- and 57-μm CH3OD Lasers and the Preliminary Experiments

“…For the laser sources, powerful 48-and 57-pim CH30D lasers pumped by a cw 9R(8) CO2 laser have been developed [3]. These lasers can be oscillated simultaneously by adjusting the laser cavity length.…”