Page 172 - Tunable Lasers Handbook

4 CO, Isotope Lasers and Their Applications 1

TABLE 1 8 Small-Signal Gain Coefficients an and Saturation Parameters IT €or a
IHe--1T160,--'aN,-Xe - Mixturea

Band Transition a. (92 cm-1 or m-1) Is (W-cm-2) woZx IW-cm-3)

Pa8 ) 0.37 30 0.11
P(24i 0.42 32 0.13
P(20) 0.45 41 0.20
P(16j 0.13 34 0.15
PilZ) 0.36 26 0.094
I
R(,I2) 0.35 26 0.091
R(16j 0.39 29 0.11
R(20) 0.39 30 0.12
R(21) 0.36 23 0.083
R(28) 0.30 19 0.057

P(28j 0.076
P(23) 0.081
P(20:) 0.086 -3 0.0026
P( 16j 0.083
P(12j 0.071
I1
R(1Z) 0.064
Ri16i 0.074
Ri2Oj 0.076
R(21) 0.065
R(28) 0.048
aReprinted with permission from Freed er al. [ 1251. Q 1982 IEEE

tubes in which four superinvar or other very low coefficient of expansion invar
alloy rods rigidly space the mirror holders to achieve maximum open-loop sta-
bility. To the best of my knowledge, this was the first use of superinvar for the
optical resonator of a laser. Furthermore. acoustic damping, magnetic shielding,
and thermal insulation of the optical cavity was achieved by a variety of materi-
als surrounding each superinvar rod in a concentrically layered arrangement.
Viscous damping cornpounds, insulating foam, lead. Mu-metal and Co-netic
magnetic shields. and aluminum foil provided this isolation of the rods. The
shielded superinvar cavity lasers yielded more than a factor-of- 100 improvement
in short-term stability compared to the first-generation stable CO, lasers built at
Lincoln Laboratory.