A. Ejiri

K. Kawahata

K. Tanaka

N. Nakazawa

S. "Okajima

Y." Itoh

National Institute for Fusion Science (NIFS-Repository)

§5. Development of Short Wavelength Far-Infrared Lasers Pumped by CW C02 Laser Okajima, S., Nakazawa, N.(Chubu Univ.), Kawahata, K., Ejiri, A., Tanaka, K., Itoh, Y. For interferometer of LI-ID, we have developed powerfull and stable 119-Jtm CH30H laser and 184-Jtm CH2F2 laser pumped by cw C02 laser [1]. For the higher density operations of LHD and for future large machine such as ITER, FIR (Far Infrared) lasers of from 40 to 100 Jlm in wavelength may be useful rather than the long wavelength FIR lasers mentioned above and 10-Jlm C02 laser from the view points of refraction and vibration effects and fringe shifts in the inter-ferometer. On this wavelength region of FIR laser spectrum, lasers from CH30H and the isotopes have a dominant role. However, the details on available lasing line, the power level and the pressure dependence have not been so well known. In order to establish new optical sources for LHD diagnostics, we have measured the characteristics for CH30H[2], CD30H[2,3], CH2I.X)H and NH3 lasers. Table 1 shows the powerful laser lines from CH2DOH and NH3 obtained with our R&D laser system. From the results, 70.5-Jtm laser (65 mW) from CH30H[2], 51-Jtm laser (17 mW) from CH2I.X)H and 67-Jtm laser (43 mW) from NH3 will be useful for future plan of LHD diagnostics. Figure 1 and 2 show the de tuning curve of 67 -Jtm NH3 laser and the pressure dependence of output power. The optimization of the laser cavity for short wave-length FIR laser is proceeding now. References 1) Okajima, S.,Kawahata, K., et.al., Proc. of 7th Int. Sympo. Laser-Aided Plasma Diagnostics, (1995, Fukuoka) 148. 2) Okajima, S.,Kawahata, K., et.al., Proc. of 21th Int. Conf. IR and~ Waves, (1996, Berlin) CT 12. 3) Okajima, S.,Kawahata, K., et.al., Ann. Rev. NIFS, 1995-1996 (1996) 103 . f-~ D... f-~ 0 0:: w U) <{ __j .LJL Fig.l. Detuning curve of 67-Jtm NH3 laser pumped by 9R(30) C02 laser. OL----'--------'---'-----L---J 0.0 0.1 0.2 0.3 0.4- 0.5 PRESSURE (torr) Fig.2. Pressure dependence of 67-Jl-m NH3 laser output. (Pump power : 54 W ) Table 1 CH2DOH and NH3 lasers pumped by cw C02 laser. (Diameter of FIR laser tube : 25 mm) C02 laser- CH2DOH line power-[W] wavelength[ J.-1. m] pol. pr-essur-e[tor-r] power[mW] 9P(1 0) 65 183.6 II 0.19 10 9 P( 1 2) 56 .1 08.8 II 0.31 1 6 56 11 2.5 II 0.31 38 9P(14) 85 206 .7 II 0.1 7 19 9P(16) 91 102.0 _L 0.29 1 5 9P(30) 95 44 II 0.13 6 1 OR(34) 74 150.8 II 0.26 22 74 * 156 _L 0.09 7 1 OP(26) 11 0 150.6 _L 0.23 24 1 OP(34) 91 124.4 II 0.43 63 1 OP(46) 43 * 51 _L 0.2 1 7 C02 laser NH3 line I power[W] wavelength[ J.-1. m]l pol. I pressure[torr]l power[mW] 9R(30) 54 67 II 0.23 43 * · new line 146 

Development of Short Wavelength Far-Infrared Lasers Pumped by CW CO2 Laser

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