Ultrashort Laser Pulse Phenomena, 2nd Edition

Stabilized Mode-Locked Lasers for Metrology 609

where we have made use of Eq. (13.18). The beat note bandwidth is thus typ-

ically three orders of magnitude smaller than that of an isolated mode of the

laser. Because the beat note is proportional to the laser bandwidth, a stabi-

lization that reduces the laser mode bandwidth by three orders of magnitude

will also reduce that of the beat note by the same amount, hence a sensitiv-

ity to rotation of the order of 10

−4

degrees per hour can be expected. The

stabilization should be applied to both pulses circulating in the cavity simul-

taneously. This requirement puts some constraints on the geometry of the cavity

and the location of the control elements. For example, in the OPO configuration

of Fig. 13.13, ...