National Research Laboratory of Metrology

ABSTRACT A CO2 laser for an optically pumped CHOH laser is stabilized on the center of the CH3OH absorption line by using a photo- acoustic spectroscopy. The frequency stability is measured by referring to a CO2 laser which is stabilized by Freed -Javan method. The stability ofthe pump laser is obtained to be iI y(t.) = 3.0 x 10 -9 x -1 2 ( 1s ./-2100s ) in the terms of the square root of Allan variance. Theoffset frequency between the CO2 laser line center and the CH3OH ab-sorption line center is also obtained from the beat frequency to be24.8 t 0.1 MHz. 1. INTRODUCTION We have constructed a frequency chain to measure the absolute pm He -Ne laser.1 Fig.1 shows a InAs frequency of methane -stabilized 3.39 frequency chain of National Re- search Laboratory of Metrology ( NRLM ). The 70.5 pm radiation from the optically pumped CH OH laser is used as one of thecoherent sources in this chain. To obtain the good stability f3=3f2-fk3 HIGH -POWERHe -Ne LASERSPECTRUMANALIZERCOUNTERMIMCH4 STABILIZEDHe -Ne LASER 3.39umKLYSTRONfk3 55GHz