Virgil E. Sanders

Multioscillator laser gyros

The two-mode ring laser gyro is reviewed. Standard bias and dither techniques are discussed that alleviate the mode locking encountered at low rotation rates. The four-mode DILAG (differential laser gyro) and its magnetic field extension the ZLAG (Zeeman laser gyro) are defined and analyzed. These devices contain two coresident ring lasers of opposite helicity and may have no moving parts. The mode-locking problems are overcome with the use of various biases that cancel out in the rate signal. A semiclassical analysis is reviewed that gives the electric field amplitudes and frequencies of the four modes in the presence of multilevel atoms, cavity anisotropy, and backscattering. It is shown that without mode-locking contributions, laser operation can be approximated very well by four independently oscillating modes. The Zeeman effects are considered. Novel scalar four-mode schemes are also discussed that circumvent the mode-locking problem.

Novel multioscillator approach to the problem of locking in two-mode ring-laser gyros.

We show theoretically that ring-laser locking between counterrunning waves can be avoided by an internally generated dither effect. Specifically, a barely oscillating detuned mode pair dithers the primary mode pair through coupling in the nonlinear medium. Experimental evidence supporting this result is presented.

Beat-note sensitivity in a Zeeman laser gyro: theory and experiment

We present data that are the first significant correlation between theory and experiment of a Zeeman laser gyro. This study concerns the behavior of the Zeeman laser-gyro beat note as a function of detuning, magnetic field, and optical activity bias. Both experiment and theory indicate the presence of a gyro configuration that is insensitive to cavity-length changes. This result has obvious importance and relevance to practical laser-gyro devices.

Optically biased laser gyro

We describe a four-mode ring laser that exhibits none of the mode-locking characteristics that plague laser gyros. This laser is characterized by a bias that changes sign with a change in the direction of rotation and prevents the counterpropagating modes from locking. A theoretical analysis explaining the experimental results is outlined.