Optical Pumping Of Helium Research Articles

A Miniature Permanent Magnet Assembly with Localized and Uniform Field with an Application to Optical Pumping of Helium

Atomic state preparation can benefit from a compact and uniform magnetic field source. Simulations and experimental measurements have been used to design, build, and test such a source and then apply it to the optical pumping of atomic helium. This source is a 9.5 mm (3/8″) OD × 6.7 mm (1/4″) ID × 9.5 mm (3/8″) long, NdFeB-N42 assembly of 1.6 mm (1/16″) thick customized annular magnets. It has octupole decay with a residual dipole far field from imperfect dipole cancelations. Fast B-field decay localizes the field, minimizing the need for shielding in applications. It has a greater than 50% clear aperture with a uniform and collimated magnetic field consistent with the prediction of several models. The device is applied to a high precision 3,4He laser spectroscopy experiment using σ+ or σ− optical pumping currently resulting in a measured 99.3% preparation efficiency and in accordance with a rate equation model.

Double-clad fiber amplifier for broadband tunable ytterbium-doped oxyorthosilicates lasers

Broadband tunable continuous-wave laser action and double-clad fiber amplifier of Yb:GSO, Yb:GYSO and Yb:LYSO crystals have been demonstrated. Under 940 nm diode pump, the free-running Yb:GSO, Yb:GYSO and Yb:LYSO lasers output power are 3.1 W at 1091 nm, 3.0 W at 1083 nm and 1.1 W at 1058 nm, with the corresponding optical-to-optical conversion efficiency of 57%, 42% and 13%, respectively. By using intra-cavity dispersion prism and a slit to restrict the spatial mode structure, continuously tunable range extends from 1002 to 1120 nm, covering some specific wavelengths as required for metrological or optical pumping applications. By using an ytterbium-doped double-clad fiber amplifier, several watts were obtained at tunable wavelengths. Particularly, the output power was 6.5 W for Yb:GSO, 12 W for Yb:GYSO, and 4 W for Yb:LYSO at 1083 nm, which matched the atomic transition wavelength useful for optical pumping of helium.

Spectroscopy of the helium 2 3 S 2 3 P transition above 0.01 Tesla application to optical pumping studies

Optical pumping of helium makes use of the 2 3S–2 3P transition at 1083 nm. We report on a study of this transition in magnetic fields up to 1.5 T. Based on these results, an optical method to measure nuclear polarisation in arbitrary field has been developed. Preliminary results on optical pumping at 0.1 T are presented.

High nuclear polarization in3He and3He-4He gas mixtures by optical pumping with a laser diode

New diode lasers delivering 50 mW output power at 1083 nm are shown to be efficient sources for optical pumping of helium. They can polarize nuclei in a3He gas up toM = 50% over the pressure range 0.4–1.6 torr. Larger nuclear polarizationsM of3He nuclei, of order 80%, can be obtained in3He-4He mixtures when the laser frequency is tuned to a4He line. A standard optical measurement of nuclear polarizationM has been extended to the case of3He-4He mixtures. The effect of various parameters on the steady-state polarizationM and on the pumping timeTp is discussed.

Optical pumping of helium with arc lamp excited LNA lasers

Optical pumping of helium with arc lamp excited LNA lasers

Polarizing ^3He nuclei with neodymium La_1−xNdxMgAl_11O_19 lasers

Optical pumping of helium, using the 23S–23P line at 1.083 μm, can be performed with a tunable neodymium laser [La1−xNdxMgAl11O19 (LNA)]. The LNA crystal, longitudinally excited by an Ar+ gas laser, delivers a usable power of about 300 mW. A 3He cell at 0.3 Torr can thus nuclearly polarized up to 60%. Preliminary results are also obtained with a LNA laser pumped by discharge lamps.