Experimental study of laser collimation of Cr beam

Abstract

Laser collimation of Cr atomic beam using a transverse Doppler cooling scheme is studied. The frequency of laser is stabilized at 5±0.26MHz below the 7S3→7PO452Cr transition. The shortest size of the laser cooling beam is computed theoretically to be 13.7mm. Accordingly a Cr beam was collimated using a transverse Doppler cooling scheme. We obtained that the transverse distribution of Cr beam is less than 1/3 of the uncooled beam.

Laser-Focused Atomic Deposition for Nanascale Grating

“…3 ) using a laser-induced fluorescence technique with stability less than 0.28 MHz (< 2π × 5 MHz). [15] Optical potential Result All depositions were carried out in a turbomolecular pumped vacuum system with typical pressure 10 −5 Pa. The chromium atomic beam is produced by thermal evaporation out of an orifice (Φ = 1 mm) of a ceramic crucible in a molecular beam epitaxy oven at 1650 • C. This leads to a typical deposition rate of 0.0125 nm/s at a distance of 0.8 m. Using Doppler cooling, a well collimated atomic beam with a divergence of <1 mrad is obtained.…”

“…A detailed investigation of the transverse laser cooling of 52 Cr was described in Ref. [15]. The experimental setup of laser-focused atomic deposition is shown in Fig.…”

“…2. This laser is divided into 4 beams: the first is for laser frequency stabil-ity (less than 0.28 MHz) using a laser-induced fluorescence (LIF) technique; [15] the second and third from the zero order diffraction of an acousto-optical modulator (AOM) are individually for the laser cooling beam and the fluorescence detecting beam; and the fourth is +1 order diffraction of the AOM (frequency shifted +250 MHz) for laser focusing used to deposit a period nanostructure. A standing light field is obtained such that the fourth beam with a 100-µm waist is retro-reflected by a 0 • mirror (reflection larger than 95%), which is directly against one face of the rightangle prime and perpendicular to the substrate.…”

“…The setup of monitoring the effect of laser cooling is the same as the one in Ref. [15]. The result is shown in Fig.…”