Blue and infrared stimulated emission from alkali vapors pumped through two-photon absorption

Sulham, Clifford V.; Pitz, Greg A.; Perram, Glen P.

doi:10.1007/s00340-010-4015-9

Cited by 49 publications

(12 citation statements)

References 17 publications

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“…To date, studies of the FWM process in diamond-type energy-level systems in alkali atoms, mostly in Rb, have focused almost exclusively on detecting the CBL and inferring details of the generation process from the blue light properties [1][2][3][4][5][6][7][8][9][10][11][12][13]. The primary reason for this is that the mid-IR radiation at 5.23 µm generated by the process of amplified spontaneous emission (ASE) is completely absorbed by the glass windows of vapour cells usually used in such experiments.…”

Section: B Velocity Selective and Velocity Insensitive Twophoton Excmentioning

confidence: 99%

Parametric wave mixing enhanced by velocity-insensitive two-photon excitation in Rb vapor

2017

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Section: B Velocity Selective and Velocity Insensitive Twophoton Excmentioning

confidence: 99%

Parametric wave mixing enhanced by velocity-insensitive two-photon excitation in Rb vapor

2017

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“…Substantially greater blue beams than previously observed are achieved by scaling the input beams to much higher intensities while adjusting their frequency detunings along with the Rb density in order to obtain optimal phase matching and input beam absorption for blue beam generation and transmission. The coherent and collimated blue light can be used as a basis for applications, such as sensitive atom detection [13], quantum information processing [14], and underwater communication [10]. The generated 1324 nm beam has seldomly been studied; however, we find it can be significant reaching levels of 2.5 mW or more.…”

mentioning

confidence: 93%

“…Incorporating an additional laser at 795 nm has been shown to both enhance and suppress the FWM process through control of optical pumping [8]. A single-frequency laser at 778 nm has also been shown to produce blue (420 nm) beams, using both cw [9] and pulsed excitation [10]. Utilizing the corresponding two-step excitation scheme in Cs, 4 μW of coherent blue light was generated at 455 nm [11], illustrating the application of this method to less ideal cases as only 0.4% of Cs atoms cascade from 6D 5∕2 → 7P 3∕2 compared to 35% of Rb 5D 5∕2 atoms, which decay through the 6P 3∕2 state [12].…”

mentioning

confidence: 99%

Collimated blue and infrared beams generated by two-photon excitation in Rb vapor

et al. 2014

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Utilizing two-photon excitation in hot Rb vapor we demonstrate the generation of collimated optical fields at 420 and 1324 nm. Input laser beams at 780 and 776 nm enter a heated Rb vapor cell collinear and circularly polarized, driving Rb atoms to the 5D 5∕2 state. Under phase-matching conditions coherence among the 5S 1∕2 → 5P 3∕2 → 5D 5∕2 → 6P 3∕2 transitions produces a blue (420 nm) beam by four-wave mixing. We also observe a forward and backward propagating IR (1324 nm) beam, due to cascading decays through the 6S 1∕2 → 5P 1∕2 states. Power saturation of the generated beams is investigated by scaling the input powers to greater than 200 mW, resulting in a coherent blue beam of 9.1 mW power, almost an order of magnitude larger than previously achieved. We measure the dependences of both beams in relation to the Rb density, the frequency detuning between Rb ground-state hyperfine levels, and the input laser intensities. A wide range of phenomena can be created by exploiting nonlinear optical processes in a dense atomic vapor. Large enhancements of these processes are possible through the generation of quantum coherences among atomic states and include effects, such as electromagnetically induced transparency, fast and slow light propagation, four-wave mixing (FWM), and lasing without inversion. FWM in particular has been shown to produce both efficient frequency upconversion [1-3] and downconversion [4] using low-power continuous-wave (cw) lasers. The newly created optical fields are narrowband tunable coherent light sources [5], with wavelengths from the IR to approaching the UV depending upon the atomic states involved. Frequency upconversion by FWM has most often been studied in Rb vapor, first demonstrated using low-power cw lasers by Zibrov et al. in 2002 [6] where 15 μW of coherent radiation at 420 nm was achieved. The method relies upon input lasers at 780 and 776 nm [see Fig. 1(a)] driving Rb atoms from the 5S 1∕2 ground state to the 5D 5∕2 state by two-photon excitation, with the 5P 3∕2 level as an intermediate state. A third optical field between the 5D 5∕2 → 6P 3∕2 levels at 5.23 μm is initiated through spontaneous emission. Strong atomic coherences are thus formed in a diamond-type energy level structure, creating coherent blue light at 420 nm (6P 3∕2 → 5S 1∕2 ) by FWM. Recent experiments achieved first 40 μW of 420 nm light through the additional coupling of both 5S 1∕2 hyperfine ground-state levels [1], and subsequently 1.1 mW by further optimization of input laser polarizations and frequencies [3]. The generated blue beam exhibits a high degree of spatial coherence [2], with a spectral linewidth typically limited by the linewidths of the applied laser fields [7]. The absolute frequency of the blue light has been found to be centered on the 6P 3∕2 → 5S 1∕2 transition, with tunability of ≥100 MHz possible by adjustment of the input laser frequencies [5]. Incorporating an additional laser at 795 nm has been shown to both enhance and suppress the FWM process through control of optical pumping [8]. ...

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“…This is largely because of the difficulty of detecting the mid-IR radiation, which is strongly absorbed in conventional Rb cells. We note that similar energy level configurations in Rb atoms have been used extensively for studying ladder-type electromagnetically induced transparency [15,16], nonlinear properties of four-wave mixing and new field generation [17,18], atomic coherence effects [19,20] and transfer of orbital angular momentum [3,21], as well as for imaging of ultracold atoms [22].…”

Section: Figurementioning

confidence: 99%

Amplified spontaneous emission at 523 μm in two-photon excited rubidium vapor

et al. 2017

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Abstract. Population inversion on the 5D5/2-6P3/2 transition in Rb atoms produced by cw laser excitation at different wavelengths has been analysed by comparing the generated mid-IR radiation at 5.23 μm originating from amplified spontaneous emission (ASE) and isotropic blue fluorescence at 420 nm. Using a novel method for detection of two photon excitation via ASE, we have observed directional coand counter-propagating emission at 5.23 μm. Evidence of a threshold-like characteristic is found in the ASE dependences on laser detuning and Rb number density. We find that the power dependences of the backward-and forwarddirected emission can be very similar and demonstrate a pronounced saturation characteristic, however their spectral dependences are not identical. The presented observations could be useful for enhancing efficiency of frequency mixing processes and new field generation in atomic media.

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Blue and infrared stimulated emission from alkali vapors pumped through two-photon absorption

Cited by 49 publications

References 17 publications

Parametric wave mixing enhanced by velocity-insensitive two-photon excitation in Rb vapor

Parametric wave mixing enhanced by velocity-insensitive two-photon excitation in Rb vapor

Collimated blue and infrared beams generated by two-photon excitation in Rb vapor

Amplified spontaneous emission at 523 μm in two-photon excited rubidium vapor

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