FASOR is an acronym for frequency addition source of optical radiation. The name is used for a certain type of guide star laser deployed at US Air Force Research Laboratory facilities

SOR Sor may refer to: * Fernando Sor (1778–1839), Spanish guitarist and composer * Sor, Ariège, a French commune * SOR Libchavy, a Czech bus manufacturer * Sor, Azerbaijan, a village * Sor, Senegal, an offshore island * Sor River, a river in th ...

and

AMOS Amos or AMOS may refer to: Arts and entertainment * Amos Records, an independent record label established in Los Angeles, California, in 1968 * Amos (band), an American Christian rock band * ''Amos'' (album), an album by Michael Ray * ''Amos' ...

. The laser light is produced in a

sum-frequency generation Sum-frequency generation (SFG) is a second order nonlinear optical process based on the annihilation of two input photons at angular frequencies \omega_1 and \omega_2 while, simultaneously, one photon at frequency \omega_3 is generated. As with ...

process from two solid-state laser sources that operate at different wavelengths. The ''frequencies'' of the sources add directly to a summed frequency. Thus, if the source wavelengths are

\lambda_1

and

\lambda_2

, the resulting wavelength is :

\lambda = \left(\frac + \frac \right)^.

Application

The FASOR was initially used for many

laser guide star A laser guide star is an artificial star image created for use in astronomical adaptive optics systems, which are employed in large telescopes in order to correct atmospheric distortion of light (called '' astronomical seeing''). Adaptive op ...

experiments. These have ranged from mapping the photon return verse wavelength, power, and pointing location in the sky. Two FASORS were used to show the advantages of 'back pumping' or pumping at both D2a and D2b lines. Later a FASOR was used to measure the earth's magnetic field.Kane, T. J., Hillman, P. D., Denman, C. A., Hart, M., Phillip Scott, R., Purucker, M. E., & Potashnik, S. J. (2018). Laser remote magnetometry using mesospheric sodium. Journal of Geophysical Research: Space Physics, 123(8), 6171-6188. It has also been used for its intended application of generating a laser guidestar for adaptive optics, see first reference. It is tuned to the D2a

hyperfine In atomic physics, hyperfine structure is defined by small shifts in otherwise degenerate energy levels and the resulting splittings in those energy levels of atoms, molecules, and ions, due to electromagnetic multipole interaction between the ...

component of the sodium D line and used to excite

sodium Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable ...

atoms in the mesospheric upper atmosphere. The FASOR consists of two single-frequency injection-locked Nd:YAG lasers close to 1064 and 1319 nm that are both

resonant Resonance describes the phenomenon of increased amplitude that occurs when the frequency of an applied periodic force (or a Fourier component of it) is equal or close to a natural frequency of the system on which it acts. When an oscilla ...

in a cavity containing a

lithium triborate Lithium triborate (LiB3O5) or LBO is a non-linear optics crystal. It has a wide transparency range, moderately high nonlinear coupling, high damage threshold and desirable chemical and mechanical properties. This crystal is often used for seco ...

(LBO) crystal, which sums the frequencies yielding 589.159 nm light.

References

{{DEFAULTSORT:Frequency Addition Source Of Optical Radiation Laser science