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41.
Phase-dependent inversionless gain in a four-level atomic system with a closed interaction loop
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A four-level atomic system with a closed interaction loop connected
by two coherent driving fields and a microwave field is
investigated. The results show that inversionless gain can be
achieved on a higher frequency transition outside the closed
interaction loop, and the gain behaviour can be modulated by the
phase of the closed loop as well as the amplitude of the microwave
field. The phase sensitivity property in such a scheme is similar to
that in an analogous configuration with spontaneously generated
coherence, but it is beyond the rigorous condition of
near-degenerate levels with non-orthogonal dipole moments.
Therefore this scheme is much more convenient in experimental
realization. 相似文献
42.
The efficiency of ultrabroad-band wavelength conversion using orthogonal-pump four-wave mixing in a semiconductor optical amplifier is measured for the wavelength shifts from 1500 to 1640 nm. The variation of conversion efficiency is < 0.9 dB over the wavelength range from 1530 to 1560 nm (C-band), and < 4.5dB over the wavelength range from 1560 to 1610 nm (L-band). The maximum conversion efficiency is about -8.7 dB. 相似文献
43.
INVERSIONLESS GAIN IN A THREE-LEVEL SYSTEM DRIVEN BY A STRONG FIELD AND COLLISIONS 总被引:1,自引:0,他引:1
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Inversionless gain in a degenerate three-level system driven by a strong external field and by collisions with a buffer gas is investigated. The mechanism of population distribution in upper laser level, contributed by the collision transfer, as well as by relaxation, induced by pressure of a buffer gas, is discussed in detail. Explicit formulae for analysis of optimal conditions are derived. The idea developed here for the incoherent pump could be generalized to other systems. 相似文献
44.
A new scheme of electromagnetically induced two-photon transparency in a four-level V-type Doppler-broadened medium is presented in this paper. Under a proper condition, the two-photon absorption can be greatly reduced by applying a control laser field with relatively lower intensity compared with that needed in other field-induced multi-photon absorption reduction. 相似文献
45.
We propose a scheme of a bistable system with an electromagnetically induced grating and analyse the optical bistabilities in the system.The stationary equations describing the system have been derived.This bistable system shows typical hysteresis behaviour. 相似文献
46.
We investigate the resonance fluorescence spectrum of an atomic three-level ladder system driven by two laser fields.We show that such a system emulates to a large degree a V-type atom with parallel dipole moments-the latter being a system that exhibits spontaneously generated coherence and can display ultrasharp spectral lines.We find a suitable energy scheme in a 85Rb atom and experimentally observe the narrowing of the central peak in a rubidium atomic beam.The corresponding spectrum can convincingly demonstrate the existence of spontaneously generated coherence. 相似文献
47.
We experimentally study the controllable generation of a beating signal using stored light pulses based on electromagnetically induced transparency(EIT) in a solid medium. The beating signal relies on an asymmetric procedure of light storage and retrieval. After storing the probe pulse into the spin coherence under the EIT condition, two-color control fields with opposite detunings instead of the initial control field are used to scatter the stored spin coherence. The controllable beating signal is generated due to alternative constructive and destructive interferences in the retrieved signal intensities. The beating of the two-color control fields is mapped into the beating of weak probe fields by using atomic spin coherence. This beating signal will be important in precise atomic spectroscopy and fast quantum limited measurements. 相似文献
48.
49.
Highly efficient four-wave mixing induced by quantum constructive interference in rubidium vapour
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We demonstrate efficient four-wave mixing with an intensity conversion efficiency of nearly 100% in theory without considering the Doppler-broadening effect in a four-level double-Λ system of hot 87Rb gas. The corresponding experimental value of about 73% was reported in our earlier work under the same conditions. This dramatic efficiency is critically dependent on the constructive interference between two four-wave mixing processes relevant to the internally generated four-wave mixing signal. 相似文献
50.
Influence of Doppler-broadening on absorption-dispersion properties in a resonant coherent medium
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We investigate the influence of Doppler broadening on absorption-dispersion
properties in a four-level atomic system that can evolve from a normal
dispersion to an anomalous dispersion. Our results show that the absorption-dispersion
properties become strongly dependent on the propagation directions of the
applied fields if Doppler broadening is taken into account. Especially, the
switchover in the sign of the dispersion is still achievable even in the
presence of Doppler broadening if properly arranging the propagation
directions of the applied fields, which is in contrast with the otherwise
behaviours in some other configurations. 相似文献