Page 320 - Tunable Lasers Handbook

280 Norman P. Barnes

77 K, pi
-
77 K, sigma
-_-
200 K, sigma

1.6 1.8 0
Wavelength (micrometers)

FIGURE 30 Polarized emission spectra of Ni:hlgFz. (Courtesy of P.F. Moulton, Schwartz
Electo-Optics.)

1 .O

- 0.8
m
.-
c
c
3
@
m
Y
%
c
.z 0.4
C
a,
c
S - 0.2
0
1.4 2.2
Wavelength (micrometers)
FIGURE 3 1 Polarized emission spectra of Co:MgF2. (Courtesy of P. F. Moulton, Schwartz
Electo-Optics.)
manifold [62]. As the temperature is increased, these peaks disappear. Near
room temperature, a broad emission peak remains. Emission for the TC polariza-
tion is peaked at shorter wavelengths, about 1.65 pm, and continues out to
beyond 2.4 pm. Emission for the CJ polarization is significantly flatter and not as
strong as the n polarized emission. Due to decreased quantum efficiency, room-
temperature fluorescence is about 0.02 as strong as fluorescence at cryogenic
temperatures, roughly in proportion with the decrease in the upper laser level
lifetime. Emission spectra from Ni:MgF, occur at somewhat shorter wave-
lengths. Again, relatively narrow emissionfeatures occur at cryogenic tempera-
tures and disappear as room temperature is approached. A broad emission peak,
extending from about 1.5 to 1.9 pm, occurs for both the CJ and x polarizations.