Page 104 - Tunable Lasers Handbook

4 CO, Isotope Lasers and Their Applications 85

FIGURE 9 Two-mirror stable laser with short intracavity cell. This laser was used for the first
demonstration of the standing-wave saturation resonance observed via the 4.3-pm fluorescence signal.

FIGURE 1 0 Schematic illustration of improved external CO, reference gas stabilization cell.

With the improved cells, significantly larger signal collection efficiency
was achieved simultaneously with a great reduction of noise due to background
radiation, which is the primary limit for high-quality InSb photovoltaic detec-
tors. We have evaluated and tested several large-area InSb detectors and deter-
mined that the LN,-cooled background greatly diminished llf noise in addition
to the expected reduction in white noise due to the lower temperature back-
ground radiation.
Figure 11 shows a typical recorder tracing of the observed 4.3-ym intensity
change as the laser frequency is tuned across the 10.59-ym P(20) line profile