NICOP - Investigation of the possibilities of coherent light return from laser guide stars
Abstract
Laser Guide Stars (LGS) are used in astronomy and military remote sensing, to characterize the degradation caused by the atmosphere and compensate it with adaptive optics. An intense lasers beam is used to energize regions of the sodium layer in the mesosphere whose responses serve as point sources to determine the atmospheric transfer function. Current LGS systems produce incoherent light backscatter from the mesosphere, and the signal-to-noise ratio (SNR) of the returns from the mesosphere are often low for some applications. The innovative S&T of this project is that it will investigate the feasibility of inducing coherent backscatter responses from sodium and other gases to increase the SNR and to potentially allow new applications of interest to the Navy. The proposed method is known as mirrorless backward lasing, which has been achieved in laboratory settings, using nonlinear interaction between resonant radiation and atomic species. The PI will use two superimposed laser beams at different wavelengths to stimulate amplified spontaneous emission (ASE) in gas cells, in the lab. This stimulation will produce a coherent, collimated backscatter toward the source of the laser beams. The effect of various parameters on the strength of the return will be investigated. An analytical model will be developed and validated. Coherent Laser Guide Stars (CLGS) can increase the mesospheric signal strength more than 10 times, and may be used for applications including remote magnetometry and navigation in the absence of GPS. In addition, applied to gas species on the surface, the coherent backscatter signal may be used to estimate local magnetic fields, as well as for remote detection of harmful gases and explosives. Steve Potashnik, Code 32, strongly supports this project and will provide co-funding. The desired outcome is a realistic model describing stimulated laser returns in an arbitrary atomic, andpossibly molecular system, and a rigorous validation with laboratory experiments using Na and Rb. The validated model will be used to optimize the returns and guide the choice of the design parameters for a future LGS system. The PI will also investigate other possible atmospheric species that might be suitable for stimulated return and remote atmospheric sensing, especially on the earth~s surface. The model, techniques, results and recommendations will be published in articles and as a chapter in the publication of ONR~s Remote Atmospheric Magnetometry Workshop.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Sep 23, 2016
- Source ID
- N629091612113
Entities
People
- Dmitry Budker
Organizations
- Office of Naval Research
- United States Navy