HELIUM-NEON LASER DISCHARGE PARAMETER STUDY.
NAVAL RESEARCH LAB WASHINGTON D C
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An experimental study was made to determine which energy level is dominant in limiting the output power of the helium-neon laser. This was done by comparing laser power versus discharge current data for the three main laser transitions, with the temperature and pressure as parameters. Such a comparison is informative because two of the laser transitions 0.6328 and 3.39 microns share a common upper level 3s2 and two 0.6328 and 1.15 microns share a common lower level 2p4. Relative saturation behavior indicates that at low pressures the upper level population rate controls the output power of all three laser lines and at high pressures above 1 torr the lower level depopulation rate is more important for the 0.63 and 1.15 microns lasers. The optimum pressure for maximum output of the 0.6328 micron laser occurs at an intermediate pressure 0.7 torr where both effects are important. All of the data were taken on the same tube, 8 mm. i.d., utilizing ultra high vacuum techniques to maintain gas purity. It was found that an increase in the laser tube wall temperature will produce an increase in laser power at high pressures as much as 500 for 1.15 microns but will decrease the power at low pressures. Also of interest in the data is the fact that the 1.15 micron line can be made to oscillate at total pressures at least as high as 20 torr. Author
- Lasers and Masers