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Proceedings Paper

Variable acquisition/communication split ratio for lasercom terminals
Author(s): Todd G. Ulmer; Frederick G. Walther
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Paper Abstract

In a lasercom terminal with co-operative acquisition and tracking, it is desirable to be able to devote all of the received power to the acquisition function while the link is being established and then switch most or all of the power to the tracking and communication functions for link operation. This ability can be especially important in a backbone terminal that interoperates with a wide range of edge terminals with different capabilities, as it can eliminate the need to optimize for one edge terminal at the expense of the others. We begin by examining link budgets for hypothetical edge terminals to establish the potential benefit to the system. We then consider three different schemes for implementing a variable acquisition/communication ratio. The first uses a bifurcating mirror to passively separate the acquisition and communications receiver paths in the backbone terminal. The second uses separate wavelengths for the acquisition and communication functions. The third uses polarization with a rotatable wave pate or its equivalent and a polarization beam splitter to vary the split ratio. We find that all three schemes are viable; the bifurcating mirror scheme is completely passive, while the wavelength scheme offers all-electronic implementation, and the polarization scheme can be implemented completely at the receiver end of the link without coordination with the remote transmitter. Any of these schemes could be implemented to relax requirements one edge terminals, allowing lower cost solutions to proliferate.

Paper Details

Date Published: 16 March 2015
PDF: 10 pages
Proc. SPIE 9354, Free-Space Laser Communication and Atmospheric Propagation XXVII, 93540P (16 March 2015); doi: 10.1117/12.2084857
Show Author Affiliations
Todd G. Ulmer, MIT Lincoln Lab. (United States)
Frederick G. Walther, MIT Lincoln Lab. (United States)

Published in SPIE Proceedings Vol. 9354:
Free-Space Laser Communication and Atmospheric Propagation XXVII
Hamid Hemmati; Don M. Boroson, Editor(s)

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