A system, circuit and method are disclosed for operating a Ring Laser
Gyroscope (RLG) off-mode-peak to avoid exciting undesirable transverse
modes. An alternate PLC operating point can be used to bias the optical
path length of the RLG to an appropriate side of an ideal integer number
of wavelengths, and thus avoid exciting the undesirable transverse modes.
Although this alternate PLC operating point is not perfect with respect
to establishing an integer number of wavelengths, this operation provides
acceptable performance of the RLG's (in particular, short length path
RLG's), and acceptable margin can be established relative to variations
in the PLC set points involved.