## Physics of Natural Fluctuations in Lasers and Non-classical Light

Prof. I.V. Sokolov,

upper level courses

I. Semi-classical theory of natural fluctuations in lasers

Elementary physical model of single-mode laser. Physical sources of fluctuations in laser emission. Temporal scales of dynamical and stochastic processes in gas laser. Description of the laser field evolution: equations for field amplitudes with random sources and Fokker-Planck equation for the field probability distribution. Field diffusion coefficients. Stationary field probability distribution below threshold. Linearized Fokker-Planck equation for the field probability distribution above threshold.

Possible schematic of observation of the intensity fluctuations spectrum of laser radiation. Temporal and spectral properties of the shot (photon) noise of photodetection in semi-classical picture. Derivation of the second order correlation function of intensity fluctuations. Physical analysis of the intensity fluctuations spectrum for the cases of weak and strong laser field. The signal to noise ratio, the role of detection efficiency.

Spectrum of laser radiation and the second order correlation function of laser field. Line shape of laser radiation in presence of the amplitude and phase diffusion. Estimate of the linewidth of laser radiation for some types of lasers. Possible schematic of observation of the frequency fluctuations spectrum of laser radiation. The second order correlation function of laser frequency. Spectral power of the signal at the output of frequency detector.

II. Novel quantum phenomena in optics

Antibunching ans sub-Poissonian statistics of photons in resonance fluorescence, physics and experimental observation.

Glauber coherent state. Quadrature field amplitudes and squeezed states. Squeezing as the light field modulation by quantum noise. Intensity noise suppression via squeezing. Parametric frequency downconversion as a source of squeezed light. Experimental observations of squeezing and direct test of the uncertainity relation.

Physical model of the pump noise suppression in laser. Sub-Poissonian laser as a source of non-classical light. Quantum phenomenological theory of the sub-Poissonian laser with regular excitation. Experimental observations of sub-Poissonian laser emission.