An equivalence is made between the exceptional points proposed by the field of non-Hermitian quantum mechanics and the dead band observed in laser gyroscopes. The sensitivity enhancement near this exceptional point is plagued by increased uncertainty due to broadening of the beat-note bandwidth. Also, near the dead band the gyroscope response is caused by Rabi intensity oscillations and not solely by a phase modulation. Finally, a distinction is made between conservative and non-conservative coupling.

For space missions, there is a need for fiber lasers of minimum power consumption involving stabilized frequency combs. We exploit the extreme sensitivity of the polarization state of circularly polarized light sent through polarization-maintaining (PM) fibers to power and temperature variations. Low-power nonlinear transmission is demonstrated by terminating a PM fiber by an appropriately oriented polarizer. The strong correlation between the power sensitivity of the polarization state and the temperature dependence of the birefringence of the PM fiber can be exploited for optical length stabilization in fiber lasers and interferometers.