Single-mode characteristic of a supermode microcavity Raman laser

Microlasers in near-degenerate supermodes lay the cornerstone for studies of non-Hermitian physics, novel light sources, and advanced sensors. Recent experiments of the stimulated scattering in supermode microcavities reported beating phenomena, interpreted as dual-mode lasing, which, however, contradicts their single-mode nature due to the clamped pump field. Here, we investigate the supermode Raman laser in a whispering-gallery microcavity and demonstrate experimentally its single-mode lasing behavior with a side-mode suppression ratio (SMSR) up to 37 dB, despite the emergence of near-degenerate supermodes by the backscattering between counterpropagating waves. Moreover, the beating signal is recognized as the transient interference during the switching process between the two supermode lasers. Self-injection is exploited to manipulate the lasing supermodes, where the SMSR is further improved by 15 dB and the laser linewidth is below 100 Hz.

Effect of Unequal Intensities of Counter-Propagating Waves on the Frequency Response of Laser Gyroscopes

Frequency response of a laser gyroscope was studies by numerical modelling of a complete system of equations describing it. The calculation results are compared to the results of experimental measurements taken on a precision dynamic test bench. The frequency response was measured for a gyroscope based on a four-mirror ring laser with a non-planar contour, operating on He-Ne active mix at the wavelength of 632.8 nm. In the gyroscope under study, the sign-variable dither was implemented on the basis of Zeeman magnetooptical effect. The relationship between the measured and designed values of the frequency response distortions has been found. The relationship between the frequency response distortions in a laser gyroscope and inequality of field intensities of the counterpropagating waves (CPW) has been numerically calculated and confirmed by experiments. Based on the research results, the parameters of a ring laser can be optimized to improve the accuracy of measurements by means of laser gyroscopes.