Coulomb broadening of the peak of electromagnetically induced transparency in plasma

We have measured the shape of the Autler-Townes doublet and the peak of electromagnetically induced transparency (EIT) under plasma conditions. We compare the experimental results with the calculated spectrum of the probe field of a three-level ArII Λ-scheme by taking into account Coulomb collisions. We show that the Coulomb broadening of the EIT peak is small (less than 40%), while the saturation resonance is broadened under the experimental conditions by a factor of 3. In contrast to the saturation resonance attributable to the Bennett dip in the velocity distribution of the population, the EIT peak is a coherent effect and is broadened mainly through Coulomb dephasing.     

Intracavity electromagnetically induced transparency

The effect of intracavity electromagnetically induced transparency (EIT) on the properties of optical resonators and active laser devices is discussed theoretically. Pronounced frequency pulling and cavity-linewidth narrowing are predicted. The EIT effect can be used to reduce classical and quantum-phase noise of the beat note of an optical oscillator substantially. Fundamental limits of this stabilization mechanism as well as its potential application to high-resolution spectroscopy are discussed.     

Birefringence in electromagnetically induced transparency

(4)He 2 (3)S(1) --> 2 (3)P transitions at 1083 nm were laser probed in the presence of radiation that coupled the 2 (3)P level with the 3 (3)S(1) level in a ladder scheme. The metastable helium that was used was produced in a rf discharge. Significant atomic birefringence was detected, in addition to complete electromagnetically induced transparency. A simple theoretical model explains the experimental results.     

Self-action of laser radiation under the conditions of electromagnetically induced transparency

The laser-radiation self-action dynamics in the electromagnetically induced transparency band were studied analytically and numerically for an atomic gas with the Λ-type energy-level scheme. The self-consistent system of equations describing the spatiotemporal evolution of a finite-amplitude wave packet in the field of a uniform pump wave was derived. The self-action in the presence of competing diffraction, nonlinear dispersion, and radiation absorption in the system was qualitatively analyzed; in particular, the conditions for self-focusing of a probe beam were determined. The results were confirmed by the numerical simulation of wave-packet spatiotemporal evolution.     

Soliton propagations in the electromagnetically induced transparency

One-dimensional pulse propagations in the electromagnetically induced media are investigated. The Maxwell-Bloch equations for a three-level medium are simplified with the approximations of slowly varying amplitudes, negligible irreversible relaxations and exact resonances. An analysis is made for the case where the integrable condition is satisfied; the oscillation strengths for the two allowed transitions are equal. Through the Bäcklund transformation, one-soliton and two-soliton solutions including the so-called simulton are derived. It is found that collisions of solitons exhibit a variety of dynamical behaviors such as elastic collisions, energy exchanges, compressions and switching phenomena depending on the initial conditions for the system. Those processes are rather common to the multi-component soliton systems and should be useful in various applications such as quantum information processings.     

Gain leveling using electromagnetically induced transparency

We propose and demonstrate a scheme of gain leveling for erbium-doped fiber amplifier (EDFA) by applying a strong coherent field to a three level amplified system using electromagnetically induced transparency. Due to the effect of this coupling field on the Stark-splitting sublevels, this scheme can be realized a flat gain operating around 1.53 μm.     

Dark-state polaritons in electromagnetically induced transparency

We identify form-stable coupled excitations of light and matter ("dark-state polaritons") associated with the propagation of quantum fields in electromagnetically induced transparency. The properties of dark-state polaritons such as the group velocity are determined by the mixing angle between light and matter components and can be controlled by an external coherent field as the pulse propagates. In particular, light pulses can be decelerated and "trapped" in which case their shape and quantum state are mapped onto metastable collective states of matter. Possible applications of this reversible coherent-control technique are discussed.     

High-speed properties of a phase-modulation scheme based on electromagnetically induced transparency

Recently a cross-phase modulation scheme that yields giant Kerr nonlinearities by use of an electromagnetically induced transparency (EIT) was proposed [Schmidt and Imamoglu, Opt. Lett. 21, 1936 (1996)]. We analyze the high-speed properties of this scheme for short-pulse propagation. We discuss the relevant losses in this system and show that for short pulses one-photon losses are dominant. We demonstrate that over the entire bandwidth the attainable phase shift in an EIT scheme with a quasi-cw coupling field is orders of magnitude higher than in a conventional three-level scheme or in EIT schemes, in which matched pulses are used to create the transparency.     

All-optical modulation based on electromagnetically induced transparency

We numerically investigate the implementation of all-optical absorption modulation of electromagnetic pulses by a medium that exhibits electromagnetically induced transparency. The quantum system is modelled as a three-level Λ-type system that interacts with two electromagnetic pulses, a probe pulse and a coupling pulse. The dynamics of the system is described by the coupled Maxwell-density matrix equations, and we explore the dependence of the optical modulation efficiency on the parameters of the system.     

Slow light with cavity electromagnetically induced transparency

We report an experimental observation of slow light propagation in cold Rb atoms exhibiting cavity electromagnetically induced transparency (EIT). The steep slope of the atomic dispersion manifested by EIT reduces the light group velocity. The cavity filtering and feedback further contribute to the slowdown and delay of the light pulse propagation. A combination of the cavity and the EIT atomic system significantly improves the performance of the slow light propagation. A propagation time delay of approximately 200 ns was observed in the cavity and Rb EIT system, which is approximately 70 times greater than the time delay calculated for the light pulse propagation through the same Rb EIT system without the cavity.     

Spatial Thirring-type solitons via electromagnetically induced transparency

We show that the giant Kerr nonlinearity in the regime of electromagnetically induced transparency in vapor can give rise to the formation of Thirring-type spatial solitons, which are supported solely by cross-phase modulation that couples the two copropagating light beams.     

Role of population transfer under strong probe conditions in electromagnetically induced transparency

We analyze theoretically the phenomenon of electromagnetically induced transparency (EIT) under conditions where the probe laser is not in the usual weak limit. We consider the effects in both three-level and four-level systems, which are either closed or open (due to losses to an external metastable level). We find that the EIT dip almost disappears in a closed three-level system but survives in an open system. In four-level systems, there is a narrow enhanced-absorption peak (EITA) at line center, which has applications as an optical clock. The peak converts to an EIT dip in a closed system, but again survives in an open system.     

Measurement of photon statistics via electromagnetically induced transparency

We propose a method to measure the photon statistics of a quantized radiation field in an electromagnetically induced transparency setup. The proposed method provides a direct way of measuring the photon statistics. This method is insensitive to the detector efficiency.     

Decoherence of electromagnetically induced transparency in atomic vapor

We report characterization of electromagnetically induced transparency (EIT) resonances in the D1 line of (87)Rb under various experimental conditions. The dependence of the EIT linewidth on the power of the pump field was investigated at various temperatures for the ground states of the lambda system associated with different hyperfine levels of the atomic 5S(1/2) state as well as magnetic sublevels of the same hyperfine level. Strictly linear behavior was observed in all cases. A theoretical analysis of our results shows that dephasing in the ground state is the main source of decoherence, with population exchange playing a minor role.     

Cavity-linewidth narrowing by means of electromagnetically induced transparency

Cavity-linewidth narrowing in a ring cavity that is due to the high dispersion and reduced absorption produced by electromagnetically induced transparency (EIT) in rubidium-atom vapor has been experimentally observed. The cavity linewidth with rubidium atoms under EIT conditions can be significantly narrowed. Cavity-linewidth narrowing was measured as a function of coupling beam power.     

Observation of electromagnetically induced transparency in cesium molecules

We have studied electromagnetically induced transparency (EIT) in diatomic cesium molecules in a vapor cell by using tunable diode lasers. We have observed a sub-natural Λ-resonance in absorption molecular band B ¹Π _u − X ¹Σ _g ⁺ at different cesium vapor pressures. The width of the EIT resonance shows a linear dependence on a cesium vapor pressure.     

Generation of nonclassical states of light in the Bose-Einstein condensate under electromagnetically induced transparency

A quantum theory of the interaction of the atomic Bose condensate with external optical fields has been developed for a two-beam Λ-scheme close to resonance. Regimes have been obtained where the coefficients of Kerr nonlinearity and nonlinear absorption reach giant values and even become negative, which gives rise to the effect of nonlinear electromagnetically induced transparency. The possibility of the efficient generation of quadrature-squeezed light under the condition of the nonlinear compensation of optical losses has been shown.