Showing papers on "Electromagnetically induced transparency published in 1998"
TL;DR: In this paper, the basic physical ideas behind electromagnetically induced transparency (EIT) are elucidated and the relation of EIT to other processes involving laser-induced atomic coherence, such as coherent population trapping, coherent adiabatic population transfer and lasing without inversion, is discussed.
Abstract: The subject of electromagnetically induced transparency (EIT) is reviewed in this paper. Emphasis is placed on the experimental work reported in this field since 1990. Theoretical work is also covered, although it is not intended to review all the very numerous recent theoretical treatments on this topic. The basic physical ideas behind EIT are elucidated. The relation of EIT to other processes involving laser-induced atomic coherence, such as coherent population trapping, coherent adiabatic population transfer and lasing without inversion, is discussed. Experimental work is described covering the following topics: EIT with pulsed and continuous-wave sources, lasing without inversion, pulse propagation in a laser dressed medium and EIT in nonlinear optical processes. A full set of references and a bibliography are included.
892 citations
TL;DR: In this paper, a theory for studying electromagnetically induced grating (EIG) in a homogeneously broadened medium consisting of three-level \ensuremath{\Lambda}-type atoms was developed.
Abstract: A strong coupling standing wave, interacting with three-level \ensuremath{\Lambda}-type (or ladder-type) atoms, can diffract a weak probe field (propagating along a direction normal to the standing wave) into high-order diffractions, a phenomenon which we name electromagnetically induced grating (EIG). We develop in this work a theory for studying EIG in a homogeneously broadened medium consisting of three-level \ensuremath{\Lambda}-type atoms. We show that by taking advantage of the absorption and dispersion properties of electromagnetically induced transparency one can create an atomic grating that can effectively diffract light into the first-order direction.
256 citations
TL;DR: In this paper, the effects of spontaneously generated coherence on the formation of a trapped state in the presence of two coherent fields of arbitrary intensity were investigated and showed that such coherence preserves both electromagnetically induced transparency and coherent population trapping (CPT) phenomena.
Abstract: Near-degenerate lower levels in a $\ensuremath{\Lambda}$ system have an additional coherence term due to interaction with the vacuum of the radiation field. We report the effects of this spontaneously generated coherence on the formation of a trapped state in the presence of two coherent fields of arbitrary intensity. We show that such coherence preserves both electromagnetically induced transparency and coherent population trapping (CPT) phenomena. However, it changes the time scales associated with the formation of the CPT state, and brings about quantitative changes in the line profiles. We present a clear analytical explanation for our numerical results. We also report the dependence of line shapes on the relative phase between the two applied fields.
182 citations
TL;DR: The EIT effect can be used to reduce classical and quantum-phase noise of the beat note of an optical oscillator substantially and fundamental limits of this stabilization mechanism as well as its potential application to high-resolution spectroscopy are discussed.
Abstract: 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.
163 citations
TL;DR: In this article, a technique for producing subfemtosecond pulses of radiation was proposed based on using electromagnetically induced transparency to produce a strongly driven molecular coherence, which results in a Raman spectrum with Bessel function amplitudes and phases corresponding to a frequency modulated signal.
Abstract: We suggest a technique for producing subfemtosecond pulses of radiation. The technique is based on using electromagnetically induced transparency to produce a strongly driven molecular coherence. This coherence results in a Raman spectrum with Bessel function amplitudes and phases corresponding to a frequency modulated signal, thereby allowing compression by the group velocity dispersion of the same medium.
143 citations
74 citations
TL;DR: In this paper, it was shown that the essential condition for the observation of EIT in solids is that the Rabi frequency of excitation must be larger than the inhomogeneous width of the transition between the two states coupled to the third state by the pair of optical fields.
Abstract: Strong evidence indicating the occurrence of electromagnetically induced transparency (EIT) in a solid medium was found. Fluorescence reduction due to EIT was observed in solids. The excitation intensity dependence of the fluorescence reduction was found to be consistent with theoretical predictions for EIT. It was experimentally demonstrated that the essential condition for the observation of EIT in solids is that the Rabi frequency of excitation must be larger than the inhomogeneous width of the transition between the two states coupled to the third state by the pair of optical fields.
63 citations
Book•
01 Jan 1998
TL;DR: In this paper, it was shown that two laser beams whose frequency difference is slightly offset from a molecular transition can, for an appropriate choice of gas pressure and cell length, generate a spectrum of Raman sidebands whose Fourier transform is a periodic train of subfemtosecond pulses.
Abstract: This Letter suggests and analyzes a technique for producing subfemtosecond pulses of radiation. We will show that two laser beams whose frequency difference is slightly offset from a molecular transition will, for an appropriate choice of gas pressure and cell length, generate a spectrum of Raman sidebands whose Fourier transform is a periodic train of subfemtosecond pulses. The essence of the technique is the concurrent generation of a frequency modulated (FM) waveform and the use of group velocity dispersion to temporally compress this waveform. By numerically modeling this process in molecular deuterium sD2d, we calculate a generated train of pulses with a pulse spacing of 11.1 fs and a pulse length of 0.21 fs. The coherence rab (Fig. 1) of the driven molecular transition is central to this work. This coherence is established by driving the molecular transition slightly off resonance with driving lasers of sufficient intensity that the product of their Rabi frequencies exceeds the product of the detuning from the molecular electronic states and the detuning from the Raman transition. With the linewidth of the applied laser pulses small as compared to the Raman detuning, the magnitude of the molecular coherence approaches 0.5, and its sign is determined by the sign of the Raman detuning. For the conditions of the previous paragraph, the generation and phase-slip lengths are of the same order, and Raman sideband generation proceeds collinearly and very differently than in the conventional low coherence regime. In essence, the molecular motion now modulates the electronic refractive index much in the same way that a low frequency electric field modulates the refractive index of a polar crystal. Incident optical frequencies become frequency modulated with peak (sinusoidal) frequency deviations and spectral bandwidths that substantially exceed the width of the visible spectrum. This allows the extension of compression techniques, such as the use of group velocity dispersion as described here, to a new regime of short pulse compression. In pertinent prior work, (1) the authors have noted how an electromagnetically induced transparency (EIT)-like excitation may be used to generate a broad comb of coherent sidebands, but the Bessel-function nature of the spectrum and the possibility of pulse compression were not
58 citations
TL;DR: In this article, the authors proposed a new kind of magnetometer that operates in the strong-fie regime leading to potentially higher signal-to-noise (SNO) ratio.
Abstract: The presence of atomic coherence manifests itself in optical properties of materials through a plethora of effe such as electromagnetically induced transparency ~EIT! @1#, enhanced index of refraction @2#, lasing without population inversion @3,4#, or resonantly enhanced nonlinear proces @5#. Among the interesting applications of these effects i proposal for a new kind of magnetometer @6,7#. Contrary to the common and established techniques of optical mag tometry @8#, it operates in the high-density – strong-fie regime leading to potentially higher signal-to-noise rati This new type of magnetometer utilizes the high dispers at an EIT resonance where the absorption is almost c pletely canceled by quantum interference. For example, for a simple three-level system, as show Fig. 1, the real part of the susceptibility of the probe tran tion, x8, close to the resonance point, is linear in the tw photon detuningD,
49 citations
TL;DR: In this article, the authors studied the transfer efficiency of stimulated Raman scattering involving adiabatic passage (STIRAP) in a molecular beam and in the bulk of the NO molecule induced by the interaction of two delayed laser pulses.
Abstract: Coherent population transfer between vibrational levels of the NO molecule induced by the interaction of two delayed laser pulses, also referred to as stimulated Raman scattering involving adiabatic passage (STIRAP), is studied experimentally in a molecular beam and in the bulk. The consequences of hyperfine splitting and Doppler broadening are discussed in detail. Unlike in previous studies of this kind, transfer occurs simultaneously between more than one group of non degenerate levels. In a molecular beam or in the bulk, the transfer efficiency of STIRAP exceeds that obtained by Stimulated Emission Pumping (SEP) by a factor of 3.6 or 15, respectively. We estimate the absolute transfer efficiency T in the beam to be \(\), while \(\) is found in the bulk. In both cases, this is \(\) of the maximum value expected from numerical studies. Possible reasons for this discrepancy are discussed. Finally we show that the absorption of a pump pulse in a weakly absorbing medium is significantly enhanced by the presence of a copropagating Stokes pulse when the Rabi frequency \(\) of the latter is smaller than the width of the Doppler profile \(\). The relation of this observation to the phenomenon of Electromagnetically Induced Transparency (EIT), which is observed for \(\), is also discussed.
49 citations
01 Jan 1998
TL;DR: The subject of electromagnetically induced transparency (EIT) is reviewed in this article, where the basic physical ideas behind EIT are elucidated and the relation of EIT to other processes involving laser-induced atomic coherence, such as coherent population trapping, coherent adiabatic population transfer and lasing without inversion, is discussed.
Abstract: The subject of electromagnetically induced transparency (EIT) is reviewed in this paper. Emphasis is placed on the experimental work reported in this ®eld since 1990. Theoretical work is also covered, although it is not intended to review all the very numerous recent theoretical treatments on this topic. The basic physical ideas behind EIT are elucidated. The relation of EIT to other processes involving laser-induced atomic coherence, such as coherent population trapping, coherent adiabatic population transfer and lasing without inversion, is discussed. Experimental work is described covering the following topics: EIT with pulsed and continuous-wave sources, lasing without inversion, pulse propagation in a laser dressed medium and EIT in nonlinear optical processes. A full set of references and a bibliography are included.
TL;DR: It is demonstrated 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.
Abstract: Recently a cross-phase modulation scheme that yields giant Kerr nonlinearities by use of an electromagnetically induced transparency (EIT) was proposed [
Schmidt
Imamo?lu
, 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.
TL;DR: In this paper, an experimental observation of transparency on a transition in the blue spectral region, induced by a continuous-wave infrared coupling field in a Doppler-broadened medium, is presented.
Abstract: An experimental observation of transparency on a transition in the blue spectral region, induced by a continuous-wave (cw) infrared coupling field in a Doppler-broadened medium, is presented. This experimental result is supported by extensive theoretical modeling of the system, a V-type scheme in atomic rubidium vapor. Transparency is observed by a 422-nm probe field on the transition between the hyperfine split ground state ${5S}_{1/2}$ and the excited state ${6P}_{1/2}.$ The coupling laser is employed on the linked transition ${5S}_{1/2}{\ensuremath{-}5P}_{3/2},$ inducing significant levels of transparency $(g70%)$ nondissipatively and in the absence of optical pumping effects.
TL;DR: In this paper, the authors conducted an experimental study of V-type electromagnetically induced transparency in sodium and showed that the detuning of the driving and probe fields can result in decreased fluorescence and absorption, in agreement with the results of numerical simulation.
Abstract: We have conducted an experimental study of V-type electromagnetically induced transparency in sodium. Its principles are elucidated by a simple model. Measurements show decreased fluorescence and absorption depending on the detuning of the driving and probe fields, which is in agreement with the results of numerical simulation.
TL;DR: In this paper, the effects of collisional dephasing and Doppler broadening on the quantum beats, narrow resonances, and probe transparency induced by quantum interference in a Vee-type atom consisting of an excited doublet coupled to a single ground level by the vacuum were investigated.
Abstract: We investigate the effects of collisional dephasing and Doppler broadening on the quantum beats, narrow resonances, and probe transparency induced by quantum interference in a Vee-type atom consisting of an excited doublet coupled to a single ground level by the vacuum. We show that the amplitudes of the quantum-beat oscillations are greatly reduced, and the narrow resonances are substantially suppressed and broadened, for even very small dephasing rates and Doppler broadening. Fluorescence quenching and the previously reported probe transparency can never occur in the presence of dephasing collisions and Doppler broadening.
TL;DR: In this article, the effects of optical pumping, coherent population trapping and light polarisation on electromagnetically induced transparency in simple Λ-type configurations of rubidium 87 where the relevant coherences are within the three Zeeman substates of the F=1 component of the 5S1/2 ground level Inversionless gain is also demonstrated.
TL;DR: In this article, the authors show that the presence of Doppler broadening does not preclude inversionless lasing for mismatched wavelengths; this is shown to hold even for Rabi splittings significantly less than the doppler width.
Abstract: Inversionless gain is predicted in a Doppler-broadened $V$ scheme for which the probe laser frequency is approximately twice that of the coupling laser. A comparison is made of inversionless gain achieved via electromagnetically induced transparency in Doppler-broadened matched and mismatched wavelength systems. We show that the presence of Doppler broadening does not preclude inversionless lasing for mismatched wavelengths; importantly, this is shown to hold even for Rabi splittings significantly less than the Doppler width. Our analysis demonstrates that inversionless gain is realizable in Doppler-broadened media, at modest continuous wave laser powers, for a probe frequency well in excess of the coupling field frequency. The presented theory is related to a practical mismatched system in atomic rubidium vapor. Approximately 8% gain is predicted in a 422 nm probe field coherently driven by a 780 nm coupling field, in the presence of a modest level of incoherent excitation.
Patent•
30 Oct 1998
TL;DR: In this article, the coupling and probe beams are tuned to transitions between the centers of gravity (COGs) of the hyperfine split energy levels, which allows high transparencies to be achieved in high opacity materials.
Abstract: A method for producing electromagnetically induced transparency (EIT) in atoms with hyperfine structure. EIT is the phenomenon in which a material (e.g. lead vapor) becomes transparent to a first electromagnetic frequency (a probe beam) when exposed to a second electromagnetic frequency (a coupling beam). In the present invention, the atom has hyperfine split energy levels. In the method of the present invention, the coupling and probe beams are tuned to transitions between the centers of gravity (COGs) of the hyperfine split levels. This allows high transparencies to be achieved in high opacity materials. Also, the present method can produce EIT in isotopically mixed materials. This is because the COGs of hyperfine split levels (in nuclear spin≢0 atoms) are generally coincident with nonhyperfine split levels (in nuclear spin=0 atoms). The method of the present invention is directly applicable to nonlinear sum and difference frequency generation.
TL;DR: In this paper, a perturbation treatment for Raman generation with a combination of long, short, and delayed laser pulses is presented, where the coupling and probe lasers are applied in a counterintuitive sequence, and the fast oscillatory contributions to populations and coherence are eliminated by robust adiabatic passage.
Abstract: A perturbation treatment for Raman generation with a combination of long, short, and delayed laser pulses is presented. When the coupling and probe lasers are applied in a counterintuitive sequence, the fast oscillatory contributions to populations and coherence are eliminated by robust adiabatic passage, allowing a much simpler solution to the problem. Such counterintuitive and on-resonance operation allows effective electromagnetically induced transparency to evolve so that the probe laser photons will experience no absorption yet still fully participate in the nonlinear frequency conversion. Consequently, better conversion efficiency should be possible. {copyright} {ital 1998} {ital The American Physical Society}
TL;DR: In this paper, the photon statistics of a quantized radiation field in an electromagnetically induced transparency setup were measured using a single photon detector. But the proposed method is insensitive to the detector efficiency.
TL;DR: In this article, a single-pass inversionless amplification by more than a factor of 10 has been measured, a significant improvement over previous experiments, and synchronously pumped laser oscillation without inversion.
Abstract: We report a lasing without inversion (LWI) experiment on the basis of coherent population trapping, realized in low-pressure cadmium vapor. A single-pass inversionless amplification by more than a factor of 10 has been measured, a significant improvement over previous experiments. In addition, we report synchronously pumped laser oscillation without inversion. Using a simple model to fit the gain/absorption curves as a function of magnetic field, we have obtained values for the populations in the system, showing that there is no inversion in the atomic basis. Combined with a simple optical method to measure absolute densities of a gas, this model results in a completely optical method to determine the absolute populations and density in the system.
TL;DR: In this article, an investigation of electromagnetically induced transparency (EIT) in sodium vapour was carried out, and a frequency transparency window was measured to have subnatural width, which is a clear indication of coherent population trapping.
Abstract: We report on an investigation of electromagnetically induced transparency (EIT) in sodium vapour. In our experiment, sodium atoms are excited on the D1-line with laser radiation containing two components with a frequency difference close to that of the two hyperfine ground states of sodium (1.772 GHz). Such an excitation leads to coherent trapping of atomic population in “dark” superpositional states, which dramatically reduces the absorption of light. A frequency transparency window is measured to have a subnatural width, which is a clear indication of coherent population trapping. Dependence of EIT on laser frequencies and intensities, on the magnetic field strength as well as on the temperature of the sodium vapour is studied.
01 Apr 1998
TL;DR: In this article, an investigation of electromagnetically induced transparency (EIT) in sodium vapour was carried out, and a frequency transparency window was measured to have subnatural width, which is a clear indication of coherent population trapping.
Abstract: We report on an investigation of electromagnetically induced transparency (EIT) in sodium vapour. In our experiment, sodium atoms are excited on the D1-line with laser radiation containing two components with a frequency difference close to that of the two hyperfine ground states of sodium (1.772 GHz). Such an excitation leads to coherent trapping of atomic population in “dark” superpositional states, which dramatically reduces the absorption of light. A frequency transparency window is measured to have a subnatural width, which is a clear indication of coherent population trapping. Dependence of EIT on laser frequencies and intensities, on the magnetic field strength as well as on the temperature of the sodium vapour is studied.
10 Aug 1998
TL;DR: The atomic coherence effect can be used in enhancing the efficiencies of nonlinear optical processes, such as nondegenerate four-wave mixing (NDFWM) in multilevel systems.
Abstract: The atomic coherence effect can be used in enhancing the efficiencies of nonlinear optical processes. Particularly, nondegenerate four-wave mixing (NDFWM) in multilevel systems has recently gained attention in connection with the advantage of using coherent population trapping (CPT) or electromagnetically induced transparency (EIT) to enhance the efficiency of generated signals. Generally speaking, linear absorption competes with the nonlinear signal generation at the exact one-photon resonance condition. However, the linear absorption can, in principle, be reduced or even eliminated by preparing the system in the CPT or EIT state. We report experimental demonstrations of NDFWM in several multi-level configurations in rubidium atomic vapor. In one of the double-/spl Lambda/ systems an unusual behavior of signal output power as a function of pump power, i.e. a maximum in the generated signal power is reached as the pump power increases, is experimentally observed. By comparing with several related /spl Lambda/ and double-/spl Lambda/ systems, we have concluded that CPT is the mechanism for this interesting effect.
TL;DR: In this article, the concepts and the physics behind electromagnetically induced transparency (EIT) and lasing without inversion (LWI) for various models of the V-type configurations are reviewed.
Abstract: We review the concepts and the physics behind electromagnetically induced transparency (EIT) and lasing without inversion (LWI) for various models of the V-type configurations.
TL;DR: In this article, it is demonstrated that pulse electron paramagnetic resonance experiments on electron-nuclear spin systems provide a simple means for studying the physics of these types of coherence phenomena.
Abstract: Dark magnetic resonance in the solid state is observed and is shown to be analogous to electromagnetically induced transparency in coherent optics. The basis of the two effects is coherent population trapping, which can conveniently be described by the product operator formalism. It is demonstrated that pulse electron paramagnetic resonance experiments on electron-nuclear spin systems provide a simple means for studying the physics of these types of coherence phenomena.
TL;DR: In this article, the authors show that for some range of parameter values, the system exhibits zero absorption accompanied by zero dispersion of the probe field, attributed to coherent population oscillations induced by the squeezed vacuum.
Abstract: The modification of the statistical properties of vacuum fluctuations, via quadrature squeezing, can dramatically reduce the absorptive and dispersive properties of two-level atoms. We show that for some range of parameter values the system exhibits zero absorption accompanied by zero dispersion of the probe field. This complete transparency is attributed to the coherent population oscillations induced by the squeezed vacuum.