Development and characterization of a 22  W narrow-linewidth 3186  nm ultraviolet laser

Abstract

We demonstrate a high-power narrow-linewidth ultraviolet (UV) laser system at 318.6 nm for direct 6S1/2-nP (n = 70 to 100) Rydberg excitation of cesium atoms. Based on commercial fiber lasers and efficient nonlinear frequency conversion technology, 2.26 W of tunable UV laser power is obtained from cavity-enhanced second harmonic generation following sum-frequency generation of two infrared lasers at 1560.5 nm and 1076.9 nm to 637.2 nm. The maximum doubling efficiency is 57.3%. The typical UV laser power root-mean-square fluctuation is less than 0.87% over 30 minutes, and the continuously tunable range of the UV laser frequency is more than 6 GHz. Its beam quality factors M 2 X and M 2 Y are 1.16 and 1.48, respectively. This high-performance UV laser has significant potential use in quantum optics and cold atom physics.

Single-Photon Rydberg Excitation and Trap-Loss Spectroscopy of Cold Cesium Atoms in a Magneto-Optical Trap by Using of a 319-nm Ultraviolet Laser System

“…[23]. The spectral linewidth is about 14.7 MHz, including the natural linewidth of 5.2 MHz from the 6P 3/2 state, the UV beam's linewidth of ∼10 kHz [16], the Doppler width at the UV wavelength of ∆f D = 2 √ ln2υ mp /λ 400 kHz, the Zeeman broadening of 6S 1/2 state in the center of the MOT along the z direction (∆f Z = µ B h g J (S 1/2 ) ∂Bz ∂z ∆z 4.6 MHz with g J (S 1/2 ) = 2), and Stark broadening of 2.8 MHz from the background electric fields. Compared with the large-scale atomic ensemble in a Cs vapour cell, the Stark broadening induced by the spatial inhomogeneity of background DC electric field for the small-scale cold atomic ensemble trapped in the MOT is much smaller.…”

“…1(b). The narrowlinewidth UV beam with a 1/e 2 diameter of ∼2.4 mm is produced by the cavity-enhanced second-harmonic generation following sum-frequency generation of two infrared lasers at 1560 nm and 1077 nm, leading to more than 2 W output power at 319 nm [16]. To reduce the influence that the radiation pressure forces the atoms out of the trap, we use a 319 nm standing wave field to excite the atoms to Rydberg states.…”

Towards implementation of a magic optical-dipole trap for confining ground-state and Rydberg-state cesium cold atoms

“…Although realization of UV laser for the single-photon Rydberg excitation is technically challenging, it is still of great significance for solving the physical issues. With the well-developed fiber laser, fiber amplifier and efficient frequency conversion PPXX material and technology, we have implemented a narrow-linewidth continuous-tunable 319-nm UV laser with more than 2 W output [40] for Cs 6S 1/2 ↔ nP 3/2 (n = 70 − 100) single-step Rydberg excitation [32][33][34]. To further realize the spatial localization of cold atomic ensemble against the atomic diffusion and decoherence caused by residual atomic thermal motion, a magic ODT will be a powerful tool for manipulating the cold atoms.…”

Autler–Townes doublet in single-photon Rydberg spectra of cesium atomic vapor with a 319 nm UV laser

“…1a. The narrow-linewidth UV laser is produced by the cavity-enhanced second harmonic generation following sum-frequency generation of two infrared lasers at 1560 nm and 1077 nm, leading to more than 2 W output power at 319 nm [23,24]. The 852 nm probe beam is provided by a distributed-Braggreflector (DBR) diode laser which is frequency stabilized to Cs 6S 1/2 (F = 4) → 6P 3/2 (F = 5, or 4, or 3) hyperfine transition by means of polarization spectroscopy [25].…”