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Optical Frequency Optimization of a High Intensity Laser Power Beaming System Utilizing VMJ Photovoltaic CellsAn effective form of wireless power transmission (WPT) has been developed to enable extended mission durations, increased coverage and added capabilities for both space and terrestrial applications that may benefit from optically delivered electrical energy. The high intensity laser power beaming (HILPB) system enables long range optical 'refueling" of electric platforms such as micro unmanned aerial vehicles (MUAV), airships, robotic exploration missions and spacecraft platforms. To further advance the HILPB technology, the focus of this investigation is to determine the optimal laser wavelength to be used with the HILPB receiver, which utilizes vertical multi-junction (VMJ) photovoltaic cells. Frequency optimization of the laser system is necessary in order to maximize the conversion efficiency at continuous high intensities, and thus increase the delivered power density of the HILPB system. Initial spectral characterizations of the device performed at the NASA Glenn Research Center (GRC) indicate the approximate range of peak optical-to-electrical conversion efficiencies, but these data sets represent transient conditions under lower levels of illumination. Extending these results to high levels of steady state illumination, with attention given to the compatibility of available commercial off-the-shelf semiconductor laser sources and atmospheric transmission constraints is the primary focus of this paper. Experimental hardware results utilizing high power continuous wave (CW) semiconductor lasers at four different operational frequencies near the indicated band gap of the photovoltaic VMJ cells are presented and discussed. In addition, the highest receiver power density achieved to date is demonstrated using a single photovoltaic VMJ cell, which provided an exceptionally high electrical output of 13.6 W/sq cm at an optical-to-electrical conversion efficiency of 24 percent. These results are very promising and scalable, as a potential 1.0 sq m HILPB receiver of similar construction would be able to generate 136 kW of electrical power under similar conditions.
Document ID
20120007096
Document Type
Technical Memorandum (TM)
Authors
Raible, Daniel E. (NASA Glenn Research Center Cleveland, OH, United States)
Dinca, Dragos (NASA Glenn Research Center Cleveland, OH, United States)
Nayfeh, Taysir H. (Cleveland State Univ. Cleveland, OH, United States)
Date Acquired
August 25, 2013
Publication Date
March 1, 2012
Subject Category
Electronics and Electrical Engineering
Report/Patent Number
NASA/TM-2012-217256
E-18011
Meeting Information
International Conference on Space Optical Systems and Applications (ICSOS)(Santa Monica, CA)
Funding Number(s)
WBS: WBS 439432.07.01.17.02
Distribution Limits
Public
Copyright
Public Use Permitted.

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