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.

Stimulated boson-peak light scattering in an aqueous suspension of spherical nanoparticles of amorphous SiO2 of similar sizes

Express diagnostics of the sizes and non-equilibrium excitation of spherical nanoparticles of amorphous silica based on boson peak stimulated scattering.

REFLECTION FROM THE NEUTRON STAR SURFACE UNDER CONDITIONS OF PLASMON-POLARITON RESONANCE AND ADDITIONAL COMPONENTS IN THE EMISSION OF A PULSAR IN THE CRAB

Additional relative to the main pulse and interpulse HF-components in the radiation of a Crab pulsar are observed in the same range where the interpulse shift occurs (Moffett, Hankins, 1996; Hankins, Jones and Eilek, 2015). The latter is explained by the specular reflection from a neutron star surface of returned positron radiation in an inclined magnetic field (Kontorovich, Trofimenko, 2017). Therefore the additional HF-components, which are substantially shifted in the rotation phase of the pulsar, can be naturally associated with (nonlinear) reflection – diffraction on the surface periodic structure. It is significant that such a structure can arise as a result of stimulated scattering on surface waves, and this scattering can occur under conditions of plasmon-polariton resonance associated with the diffraction spectrum sliding along the surface, which significantly reduces the stimulated scattering threshold. The large width of the components is explained by the continuous radiation spectrum of returned positrons incident on the surface. Although this mechanism found itself in the Crab pulsar due to a unique combination of parameters at centimeter wavelengths, it is completely common to pulsars. Another possibility – diffraction by a periodic structure due to the action of constant fields (electric or magnetic) − requires some separate consideration. The content of the report corresponds to publications (Kontorovich et al., 2018).