Page 36 - Tunable Lasers Handbook

2 Narrow-tinewidth Laser Oscillators 7

I I

I
I

1-1 I J x
I
I
I

I I
a -4
F IGURE 4 Multiple-prism grating assembly. The expanded beam(s) illuminates a transmission
grating Q) and interference occurs at x. (Reprinted with permission from Duarte [37] and Elsevier
Science.)

For one dimension we can write ~(r,~y) Y(r,) and Y(rlup) = Y'(rm) and Eq. 4
=
reduces to

Expanding Eq. (5) and rearranging the exponential terms lead to eq. (2).

5. DISPERSION LINEWIDTH EQUATION

The dispersive linewidth in a pulsed high-gain laser is determined by the
expression

where A0 is the beam divergence and (d0/ah) is the intracavity dispersion. This
simple equation indicates that in order to achieve narrow-linewidth emission, A0