Nikolai V Kravtsov

A nonlinear electrodynamical shift of spectral lines in the hydrogen atom and hydrogen-like ions

The shift of spectral lines in the hydrogen atom and hydrogen-like ions is calculated using Born-Infeld nonlinear electrodynamics. The formulas obtained show that the position of the s levels in hydrogen-like ions and muonic atoms should be most strongly affected by the nonlinearity of electrodynamics of vacuum.

Relaxation oscillations in a self-modulated solid-state ring laser

Abstract Noise driven relaxation oscillations of a solid-state ring laser undergoing stable dynamical periodic pulsation are investigated for the first time. Formulas for the relaxation oscillation frequencies in the presence of frequency nonreciprocity are derived. It is shown that, in the case of symmetric backscattering, the self-modulation regime is characterized by damped relaxation oscillations. The conditions are found for which the relaxation oscillation frequencies are nondegenerate over the whole range in which the frequency nonreciprocity can be varied. The dependence of the relaxation oscillation frequencies on parameters of the sinusoidally alternating bidirectional ring laser is substantially different from the corresponding dependence for unidirectional operation.

Optical effects in a rotating frame of reference

The laws governing the propagation of light waves in a rotating frame of reference are investigated. It is shown that a curvature of light beams is possible in a noninertial frame of reference. This effect can be observed experimentally with the use of modern laser techniques.

Chaotic synchronization and evolution of optical phase in a bidirectional solid-state ring laser

We present results on experimental and theoretical studies of chaos in a solid-state ring laser with periodic pump modulation. We show that the synchronized chaos in the counter-propagating waves is observed for the values of pump modulation frequency fp satisfying the inequality f1 < fp < f2. The boundaries of this region, f1 and f2, depend on the pump-modulation depth. Inside the region of synchronized chaos we study not only dynamics of amplitudes of the counter-propagating waves but also the optical phases of them by mixing the fields of the counter-propagating waves and recording the intensity of the mixed signal. We demonstrate experimentally that in the regime of synchronized chaos the regular phase jumps appear during intervals between adjacent chaotic pulses. We improve the standard semi-classical model of a SSRL and consider an effect of spontaneous emission noise on the temporal evolution of intensities and phase dynamics in the regime of synchronized chaos. It is shown that at the parameters of the experimentally studied laser the noise strongly affects the temporal dependence of amplitudes of the counter-propagating waves.

Gd3Ga5O12:Nd3+ crystals for a continuous-wave diode-pumped laser operating in 4F3/2 → 4I11/2 and 4F3/2 → 4I13/2 channels

Garnet crystals of the composition Gd3Ga5O12:Nd3+ (concentration series CNd = 1–10 at. %) were grown from flux. In terms of spectroscopy, these crystals, unlike those grown from melts, form medium with a single activator center. For the first time, continuous-wave lasing was excited by diode pumping with the use of Gd3Ga5O12:Nd3+ crystals at the wavelengths λ3 = 1.3315 and λ4 = 1.3370 μm of the 4F3/2 → 4I13/2 channel and also the simultaneous generation at two wavelengths, λ1 = 1.0621 and λ2 = 1.0600 μm, of the 4F3/2 → 4I11/2 channel.

On verifying the universality of gravitational interaction using an optical method

Experiments with a laser gyro can verify the universality principle for the gravitational interaction of photons with respect to the components g0ϕ with an accuracy no worse than 10−16.

Unidirectional single-mode lasing on Nd-doped GSGG crystal

Abstract The lasing characteristics of a Cr,Nd:GSGG solid state ring laser with different types of monochromatic pumping have been investigated. Unidirectional, single frequency lasing of the ring nonplanar laser was obtained. A high stable automodulation regime of lasing with a high sensitivity to the magnetic field was realized.

Non-reciprocal effects in spatially inhomogeneous, nonlinear media

The possibility of non-reciprocal effects developing in a ring laser with a cavity that includes spatially inhomogeneous, nonlinear elements is analyzed. The occurrence of non-reciprocal effects in intracavity generation of the second harmonic and stimulated Raman scattering is considered.

Polarisation magneto-optical effects in a diode-pumped cw Nd{sup 3+}:Bi{sub 4}Ge{sub 3}O{sub 12} laser oscillating at 1.06425 and 1.3418 {mu}m

The characteristics of a cw Nd3+:Bi4Ge3O12 laser oscillating at 1.06425 μm are studied as functions of the strength of a longitudinal magnetic field. The laser was found to be highly sensitive to the action of an alternating magnetic field with a frequency equal to the frequency of relaxation oscillations. The cw lasing was also obtained at 1.3418 μm.

A low-temperature Nd:YAG ring chip laser

The performance of ring chip lasers at the temperature of liquid nitrogen has been studied. It is demonstrated that the amplitude and frequency stability of laser radiation is substantially improved for both unidirectional lasing and the self-modulation mode of bidirectional lasing.