Collimated UV light generation by two-photon excitation to a Rydberg state in Rb vapor

Abstract

We use two continuous-wave (CW) laser beams of 780 nm and 515 nm to optically drive 85 Rb atoms in a heated vapor cell to a low-lying Rydberg state 10D 5/2 . We observe a collimated ultraviolet (UV) beam at 311 nm, corresponding to the transition frequency from the 11P 3/2 state to the 5S 1/2 state. This indicates the presence of a coherent four-wave mixing process, built up by two input laser fields as well as a terahertz (THz) radiation of 3.28 THz that is generated by amplified spontaneous emission between the 10D 5/2 and the 11P 3/2 states. We characterize the 311 nm UV light generation and its dependence on various physical parameters. This scheme could open up a new possibility for generating narrow-band THz waves as well as deep UV radiation.

Directional THz generation in hot Rb vapor excited to a Rydberg state

“…Directional THz radiation is created from population inversion between Rydberg states, followed by amplified spontaneous emission (ASE), i.e., amplification via stimulated emission in free space. This work significantly extends previous experiments [17,18] where the presence of THz radiation was inferred from the observed UV light generated by four-wave mixing. In our current experiment, gener-ated THz fields are detected directly, which is achieved by a custom-built vacuum cell with a silicon window that transmits THz radiation.…”

“…According to Table I, these two transitions have by far the largest transition dipole-matrix elements, and should thus make the dominant contribution to the generated THz radiation. As in our previous work [17], we also detect the UV light emitted on the 11P 3/2 → 5S 1/2 transition (transition 4) via four-wave mixing.…”

Spiking dynamics of frequency upconverted field generated in continuous-wave excited rubidium vapors

“…Nonlinear parametric and nonparametric processes in atomic media generate new optical fields with substantially different wavelengths to those used for excitation [1]. The frequency conversion of continuous wave (cw) laser light with a power of several tenths of a milliwatt into directional blue, ultraviolet and mid-infrared (IR) radiation in alkali vapours continues to be an active topic of research [2][3][4][5][6][7][8][9][10][11][12][13][14].…”

Intensity-correlated spiking of infrared and ultraviolet emission from sodium vapors

“…We note that despite frequency up-and down-conversion of resonant radiation in alkali vapours becoming an active topic of research [16][17][18][19][20][21][22][23][24][25][26], surprisingly little is known about temporal characteristics of the generated fields.…”