Advances of Research on Dual-Frequency Solid-State Lasers for Synthetic-Wave Absolute-Distance Interferometry.

Frequency-difference-stabilized dual-frequency solid-state lasers with tunable and large frequency difference have become an ideal light source for the high-accuracy absolute-distance interferometric system due to their stable multistage synthetic wavelengths. In this work, the advances in research on oscillation principles and key technologies of the different kinds of dual-frequency solid-state lasers are reviewed, including birefringent dual-frequency solid-state lasers, biaxial and two-cavity dual-frequency solid-state lasers. The system composition, operating principle, and some main experimental results are briefly introduced. Several typical frequency-difference stabilizing systems for dual-frequency solid-state lasers are introduced and analyzed. The main development trends of research on dual-frequency solid-state lasers are predicted.

Optimization of Ring Laser Gyroscope Bias Compensation Algorithm in Variable Temperature Environment.

In a high accuracy strapdown inertial navigation system (SINS), the ring laser gyroscope's (RLG) bias changes and the performance decreases due to factors in the RLG's self-heating and changes in ambient temperature. Therefore, it is important to study the bias temperature drift characteristics of RLGs in high, low, and variable temperature environments. In this paper, a composite temperature calibration scheme is proposed. The composite temperature model introduces the derivative term and the temperature derivative cross-multiplier on the basis of the static model and sets the overlap regions for the piecewise least squares fitting. The results show that the composite temperature model can compensate the bias trend term well at ambient temperature, improve the fitting accuracy, and smooth the output curve. The compensation method has a small amount of calculations and flexible parameter design. The precision of the laser gyros in one SINS is improved by about 64.9%, 15.7%, and 3.6%, respectively, which has certain engineering application value.

Self-biasing phenomenon in prism laser gyro operating in double-longitudinal-mode state.

This study experimentally reveals the self-biasing phenomenon in prism laser gyros. When the gyro operates in a specific double longitudinal mode and four-frequency oscillation state, the gyro can detect the normal angular velocity component of the Earth's rotation without dithering, the self-biasing status is induced. In this study, a laboratory platform of the self-biasing laser gyro is established. The two longitudinal modes oscillate on both sides of the gain curve. The intensity ratio of the strong and weak modes is about 1.4 to 1, and the coupling effects of these two modes with parallel linear polarization have been discussed using Lamb theory. Because the adverse effects of biasing technical are avoided, the self-biasing gyro has potential to challenge the strategic precision.