Page 199 - Tunable Lasers Handbook

5 Dye Lasers 177
A

Trapezoidal 1 Dye a
T region

E7 _t Dye
Para1 lelograrrmatic
T reg'on

Rectangular angle 0
-tDYe
Rectangular D
T region
If"

inclined
at
cell
d
Q (front view)
I
FIGURE 4 Dye laser cell geomenies: (a) Trapezoidal. (bJ Parallelogrammatic. (c) Rectangular.
Here the cross sections of the dye cells are shown parallel to the plane of propagation (that is, top
vieu). (d) Rectangular geometry cells are often used inclined at a few-degree angle. (Reproduced
with permission from Duarte [37].)

oscillator configurations including telescopic, grazing-incidence, multiple-prism
Littrow (WL), and hybrid multiple-prism grazing-incidence (HMPGI) grating
oscillators are listed in Table 1 of Chapter 2. Parameters considered in this table
include tuning range, laser linewidth, and conversion efficiency.
A very important parameter in narrow-linewidth dye laser oscillators is the
amplified spontaneous emission (ASE) level. One approach to quantify the ASE
level is to measure the ASE 7i present in the output. Although this is a useful
approach used by many authors, it does not provide information on the spectral
brightness of the laser. A measure of ASE that does include information on spec-
tral density is [37]:

Here 4A is the full width of the ASE emission energy W(A), and Ak is the
linewidth of the laser emission energy E(h). For the special case of identical
energy distributions for the ASE and laser emission, Eq. (13) reduces to the ratio
of the maximum intensities (ZAsE/Zl). The ASE 9% can be obtained bjj multiplying