Powerful optically pumped far-infrared laser with stable output power

This paper describes the characteristics of the output stability of a power ful optically pumped far-infrared laser and the related physical phenomena used to measure and to improve the stability characteristics. First, we men tion that the frequency stability of the CO2 pump laser, measured with Dopp ler-free and pressure-broadened Stark Lamb dip signals, is about 250 kHz(dr ift) per hour in the free-running mode and about 150 kHz(p.p) in the active ly stabilized mode. Next, we show that optical resonant feedback disturbed the output stability of our far-infrared laser. Then, we show that the outp ut stability, resonant feedback, and temperature stability are closely rela ted and that stable output can be obtained by controlling the temperature b y using high-power chillers and a long idling time. Offset-hole input coupl ers also reduce the feedback. As a result, FIR output is stabilized to with in a few percent.