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Time-reversed lasing and control of absorption in a two-channel coherent perfect absorber

Wan , Chong, Ge +3 more

Conference on Lasers and Electro-OpticsJan 1, 20110 citations

Grating Enhanced Gain and Reverse Oscillations in a Sodium Vapor Laser: Evidence for Collective Atomic Recoil Lasing (CARL)

Philip Hemmer, M. S. Shahriar, D. P. Katz +3 more

Springer eBooksJan 1, 19960 citations

Time-delayed laser-induced double gratings with broadband lights

Xin Mi, Zuhe Yu, Qian Jiang +1 more

Optics CommunicationsMay 1, 19952 citations

Coherent perfect absorption in a homogeneously broadened two-level medium

Stefano Longhi

In recent works, it has been shown, rather generally, that the time-reversed process of lasing at threshold realizes a coherent perfect absorber (CPA). In a CPA, a lossy medium in an optical cavity with a specific degree of dissipation, equal in modulus to the gain of the lasing medium, can perfectly absorb coherent optical waves that are the time-reversed counterpart of the lasing field. Here, the time-reversed process of lasing is considered in detail for a homogeneously broadened two-level medium in an optical cavity and the conditions for CPA are derived. It is shown that, owing to the dispersive properties of the two-level medium, exact time-reversal symmetry is broken and the frequency of the field at which CPA occurs is generally different than the one of the lasing mode. Moreover, at a large cooperation parameter, the observation of CPA in the presence of bistability requires one to operate in the upper branch of the hysteresis cycle.In recent works, it has been shown, rather generally, that the time-reversed process of lasing at threshold realizes a coherent perfect absorber (CPA). In a CPA, a lossy medium in an optical cavity with a specific degree of dissipation, equal in modulus to the gain of the lasing medium, can perfectly absorb coherent optical waves that are the time-reversed counterpart of the lasing field. Here, the time-reversed process of lasing is considered in detail for a homogeneously broadened two-level medium in an optical cavity and the conditions for CPA are derived. It is shown that, owing to the dispersive properties of the two-level medium, exact time-reversal symmetry is broken and the frequency of the field at which CPA occurs is generally different than the one of the lasing mode. Moreover, at a large cooperation parameter, the observation of CPA in the presence of bistability requires one to operate in the upper branch of the hysteresis cycle.

arXiv:1111.3463Physical Review AMay 24, 201188 citations

Nonlinear dynamics in lasing without inversion

J. Mompart, R. Corbal�n, Ramon A. Vilaseca

Radiophysics and Quantum ElectronicsOct 1, 20042 citations

New light-matter phase: Asymmetric nonlinear self-consistent grating in a low-Q CW superradiant laser with symmetric Fabry-Perot cavity

Vl. V. Kocharovsky, Alexey Mishin, E. R. Kocharovskaya +2 more

We carry out numerical modelling of the Maxwell-Bloch equations for a CW superradiant lasing of a homogeneous two-level active medium in a symmetric low-Q Fabry-Perot cavity and find a remarkable phase transition. Namely, at a pumping level n > n ( a ) exceeding by several times the lasing threshold, n ( s ) , a stationary (or nonstationary multimode) lasing of more or less symmetric counter-propagating electromagnetic waves is replaced with a steady-state monochromatic (or weakly modulated) lasing of asymmetric counter-propagating waves with different amplitudes a + , a − . The spontaneous transition to a new field structure is accompanied by formation of a highly asymmetric strongly nonlinear half-wavelength grating of the self-consistent polarization and population inversion of active medium n z [1] , [2] . Many similar numerical runs with noise taking into account show that in a rather wide range of laser parameters the grating appears with equal probabilities 50:50 at one and the same distance from left or right ends of an active sample and has always one and the same asymmetric profile n z ( ζ ) with maximum at symmetric points with respect to the cavity center ζ = 0. As a rule, a formation of the steady-state grating takes a long transient period of time and includes generation of several superradiant pulses (see Fig. 1a ).We carry out numerical modelling of the Maxwell-Bloch equations for a CW superradiant lasing of a homogeneous two-level active medium in a symmetric low-Q Fabry-Perot cavity and find a remarkable phase transition. Namely, at a pumping level n > n ( a ) exceeding by several times the lasing threshold, n ( s ) , a stationary (or nonstationary multimode) lasing of more or less symmetric counter-propagating electromagnetic waves is replaced with a steady-state monochromatic (or weakly modulated) lasing of asymmetric counter-propagating waves with different amplitudes a + , a − . The spontaneous transition to a new field structure is accompanied by formation of a highly asymmetric strongly nonlinear half-wavelength grating of the self-consistent polarization and population inversion of active medium n z [1] , [2] . Many similar numerical runs with noise taking into account show that in a rather wide range of laser parameters the grating appears with equal probabilities 50:50 at one and the same distance from left or right ends of an active sample and has always one and the same asymmetric profile n z ( ζ ) with maximum at symmetric points with respect to the cavity center ζ = 0. As a rule, a formation of the steady-state grating takes a long transient period of time and includes generation of several superradiant pulses (see Fig. 1a ).

Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)Jun 21, 20210 citations

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