Optical Pumping


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Optical pumping

The process of causing strong deviations from thermal equilibrium populations of selected quantized states of different energy in atomic or molecular systems by the use of optical radiation (that is, light of wavelengths in or near the visible spectrum), called the pumping radiation.

Optical pumping is vital for light amplification by stimulated emission in an important class of lasers. For example, the action of the ruby laser involves the fluorescent emission of red light by a transition from an excited level E2 to the ground level E1. In this case E2 is relatively high above El and the equilibrium population of E2 is practically zero. Amplification of the red light by laser action requires that number of atoms N2 exceed N1 (population inversion). The inversion is accomplished by intense green and violet light from an external source which excites the chromium ion in the ruby to a band of levels, E3 above E2. From E3 the ion rapidly drops without radiation to E2, in which its lifetime is relatively long for an excited state. Sufficiently intense pumping forces more luminescent ions into E2 by way of the E3 levels than remain in the ground state E1, and amplification of the red emission of the ruby by stimulated emission can then occur. See Laser

Optical Pumping

 

the excitation of the microparticles, such as atoms and molecules, that make up matter from a lower energy level to a higher level by the use of light.

optical pumping

[′äp·tə·kəl ′pəmp·iŋ]
(optics)
The process of causing strong deviations from thermal equilibrium populations of selected quantized states of different energy in atomic or molecular systems by the use of electromagnetic radiation in or near the visible region.
References in periodicals archive ?
The apparatus must utilize ultrashort broadband terahertz pulses to allow imaging and spectroscopy of terahertz conductivity and ultrafast terahertz photoconductivity on a nanometric scale (ie, The system must allow time-resolved optical pumping experiments - thz near field probing).
Caption: Neodymium-alumina (left) shows no signs of cracking at 40W applied optical pumping at 808nm, while neodymium-YAG (right) cracks at 25W
As can be seen in Figure 15 when starting the optical pumping of the laser crystal, the helium-neon laser beam converges as a result of the thermal lens within the crystal Nd: KGW as a result of pumping.
Among their topics are the xenon chemical shift and chemical shift anisotropy, principles and practices of spin-exchange optical pumping at high xenon densities and laser fluxes, biosensing and the study of biological cells using hyperpolarized 129xenon, continuous flow and dissolved phase 129xenon nuclear magnetic resonance/magnetic resonance imaging for quantifying in preclinical study as well as materials science, and hyperpolarized xenon nuclear magnetic resonance/magnetic resonance imaging signal amplification by gas extraction and remote detection.
As an alternative to electrical pumping in VCSELs, optical pumping may be used which can inject excitation carriers uniformly across a wide area [4, 6].
The coherence induced in this structure is due to the coupling of two exciton states arising from tunnelling instead of optical pumping process [25].
Figure 2 shows the optical pumping over the F = 4 [right arrow] F = 3 transition of the cesium D1 absorption line using right circularly polarized light, which results in photon's angular momentum equal to +1.
Besides the optical pumping of fiber lasers, direct processing of metals--welding, brazing, cutting, hardening, cladding, and coating--for use in automotive manufacturing is one of the main applications of infrared lasers with more than 1 kW of power.
Coverage overlaps with the many texts that cover laser spectroscopy and quantum optics, but this text is distinguished by discussion of topics from a variety of viewpoints and by inclusion of topics not readily available in other introductory texts such as atom optics and interferometry, optical pumping, light scattering, and sub-Doppler laser cooling.
For example, the addition of zinc oxide nanoparticles into the epoxy shows laser-like behavior upon optical pumping. The addition of barium titanate (BaTiO3) nanoparticles results in high capacitance.
To achieve light amplification and lasing, one has to be able to realize net optical gain in an active medium by either electrical or optical pumping. Owing to the fact that silicon is an indirect band gap semiconductor, internal quantum efficiency of light emission associated with band-to-band transition in silicon is many orders of magnitude smaller than that for direct band gap III-V compound semiconductors, such as GaAs and InP.