Page 171 - Tunable Lasers Handbook

150 Charles Freed

TABLE 17 Small-Signal Gain Coefficients a. and Saturation Parameters Z, for a
4He--1~C180,--14NN,-Xe Mixture0

Band Transition uo (% cm-1 or m-1) I, (W-cm-2) uuIs (W-cm-3)

P(28) 0.37 33 0.12
P(24) 0.40 35 0.14
P(20) 0.42 39 0.17
P(16) 0.37 30 0.1 1
P(12J 0.32 18 0.057
I
R(12) 0.30 23 0.070
R(16) 0.34 24 0.081
R(20) 0.31 27 0.091
R(24) 0.33 23 0.077
R(28) 0.31 16 0.05 1

0.38 23 0.087
0.42 29 0.12
0.41 32 0.13
0.39 30 0.12
0.32 19 0.063

0.28 15 0.044
0.34 23 0.079
0.37 27 0.10
0.37 26 0.096
0.31 23 0.078
nReprinted with permission from Freed er al. [125]. 0 1983 IEEE.

and output characteristics of the various designs may be found (in chronological
order) in [ 130.55,72,16,77,56,63]. Virtually all experimental results described in
this chapter were obtained with the (so-called) third-generation lasers [72,56]
that have been in use at Lincoln Laboratory since the beginning of 1968. Most of
the stable CO, (and CO) laser oscillators that were designed and constructed at
Lincoln Laboratory have several common features, described as follows.
A nearly semiconfocal optical cavity configuration is used, which yields a
ratio of relative diffraction loss of about 10 to 1 between the low-loss off-axis
TEMlo, mode and the desired fundamental TEM,,, mode. In general, only fun-
damental TEM,,, mode operation can overcome the combined losses, which are
due to output coupling and diffraction. The lasers are dc-excited internal-mirror