Izvestiya of Saratov University.
ISSN 1817-3020 (Print)
ISSN 2542-193X (Online)


frequency modulation

Nanodisplacement measurements by frequency-modulated laser autodyne

Background and Objectives: Measurements of nanodisplacements are relevant for various applications of self-mixing laser (autodyne), in particular when they are combined with microwave probe methods, which are sensitive not only to the profile, but also to the inhomogeneities of the material and the its internal structure. A laser autodyne method for measuring the nanodisplacement by triangular frequency modulation of the laser radiation is proposed.

Spatio-Temporal Dynamics of Modulated cw Laser Beam in Spatial-Extended Nonlinear Medium

On the basis of spatio-temporal numerical model the dynamics of frequency-modulated cw laser beam propagating in resonance conditions is investigated. At modulation periods comparable with the atomic relaxation times the time and frequency dependence of the output intensity exhibits the manifestations of delayed medium response and resonance self-action. Time dependence of output intensity and spot size are measurement parameters. On the basis of phase portraits and power spectrum analysis we found a different dynamical regimes.

Non-Stationary Coherent Population Trapping in Frequency-Modulated Fields

Coherent population trapping (CPT) resonance formation is modeled numerically in a three-level Λ-system with one of the near-resonance fields being frequency-modulated. The model is based on density matrix equations in RW approximation with atomic relaxation properly taken into account. Slow modulation is shown to be equivalent to CW excitation with the frequency changed point by point.

Optical Transient Nutation in Frequency-modulated cw Laser Beams in Resonant Self-Action Conditions

On the basis of numerical simulations an optical transient nutation is investigated. This effect is developed on high modulation amplitude of frequency-modulated cw laser beam propagating in resonance conditions. At modulation periods comparable with the atomic relaxation times the time dependence of the output intensity exhibits the combined manifestations of optical nutation and resonance self-action.