Development of a high power 236 MHz tunable bandwidth carbon dioxide laser system for pumping large offset far infrared laser lines.

摘要

A CO2 laser was designed, and constructed, with a 236 MHz tunable bandwidth. A fast detector was used to measure the tunable bandwidth by mixing the laser with a commercially available CO2 laser and looking at the resulting beat frequencies. The gas flow design employed a roots pump in order to achieve a factor of 17 increase in flow rate creating a factor of two increase in laser gain. This increase in laser gain offset the losses associated with the increased tunable bandwidth resulting in an output power of 65 Watts. The mode quality of the laser was investigated demonstrating lasing in the TEM10 Laguerre-Gaussian mode. The laser design included a tunable blaze grating, which allowed the laser to be tuned over a wide rage discrete frequencies in the CO2 spectrum. Data was collected at 14 different CO2 transitions from 9.3 mum to 10.65 mum. The laser was also used to optically pump several far infrared laser lines producing power up to 7.75 mWatts. The power and stability of the far infrared laser lines was investigated while running the CO2 laser both in the fast gas flow regime and the slow gas flow regime. An effect know as the transferred Lamb-dip was observed while running the 513.02 mum laser line in HCOOH. This transferred Lamb-dip showed some dependence on the pump power and far infrared gas pressure. This effect was investigated and some tentative conclusions were drawn as to the cause.