NASA Scientific and Technical Aerospace Reports

20040047127 Raytheon Electronic Systems, El Segundo, CA, USA
RF Photonics for Beamforming and Array Applications
Lee, J. J.; Optics Microwave Interactions; April 2003, pp. 4-1 - 4-9; In English; See also 20040047121; Copyright; Avail:
CASI; A02, Hardcopy
This paper was prepared for NATO’s RTA Lecture Series No. 229 presented at the workshop of Optics-Microwave
Interactions in September 2002. This lecture focuses on the applications of RF photonics for array antennas in signal
distribution, beamforming, beam control, and antenna remoting. Examples are given to discuss the requirements, benefits, and
design approaches of photonics for phased array antennas. The first demonstration of using photonics for a dual band array
was conducted in 1990. Later a wide band conformal array controlled by photonics was built and tested. This example talks
about the optical control of phased arrays by using fiber-optic links for RF and data remoting and a time-shift beamforming
network for wide instantaneous bandwidth. Last, the talk will illustrate how photonics can be used to form a wide band feed
system for multibeam arrays.
Author
Radio Frequencies; Photonics; Beamforming; Antenna Arrays
20040047241 Lawrence Livermore National Lab., Livermore, CA
Modeling of Long-Range Atmospheric Lasercom Links Between Static and Mobile Platforms
Scharlemann, E. T.; Breitfeller, E. F.; Henderson, J. R.; Kallman, J. S.; Morris, J. R.; Jul. 29, 2003; 14 pp.; In English
Report No.(s): DE2004-15005837; UCRL-JC-151554; No Copyright; Avail: Department of Energy Information Bridge
We describe modeling and simulation of long-range terrestrial laser communications links between static and mobile
platforms. Atmospheric turbulence modeling, along with pointing, tracking and acquisition models are combined to provide
an overall capability to estimate communications link performance.
NTIS
Optical Communication; Communication Networks; Atmospheric Models
20040047247 Alabama Univ., Huntsville, AL, USA
Characteristic Matrices for Spherical Shell Photonic Systems
Fuller, Kirk A.; Smith, David D.; January 2004; 3 pp.; In English; No Copyright; Avail: CASI; A01, Hardcopy
We establish a parallel between the transfer matrix used in the study of plane-parallel photonic structures and the matrix
characterizing transfer of partial waves in concentric spheres. We derive explicit expressions for the elements of the transfer
matrix for concentric spherical layers, and from those expressions derive the scattering coefficients of a multilayered sphere.
The transfer matrices are 4x4 block diagonal with only four independent elements. Matrix elements for the case of TM waves
are related to those for the case of TE waves through simple interchange and multiplicative constants. In analogy with plane
parallel layers, the transfer matrix for concentric multilayers is simply the product of the transfer matrices of the individual
layers.
Author
Matrices (Mathematics); Spherical Shells; Photonics; Laminates; Analogies
20040047262 Lawrence Livermore National Lab., Livermore, CA
Horizontal Path Laser Communications Employing MEMS Adaptive Optics Correction
Thompson, C. A.; Wilks, S. C.; Brase, J. M.; Young, R. A.; Johnson, G. W.; Sep. 05, 2001; 14 pp.; In English
Report No.(s): DE2004-15005679; UCRL-JC-145326; No Copyright; Avail: Department of Energy Information Bridge
Horizontal path laser communications are beginning to provide attractive alternatives for high-speed optical
communications, In particular, companies are beginning to sell fiberless alternatives for intranet and sporting event video.
These applications are primarily aimed at short distance applications (on the order of 1 km pathlength). There exists a potential
need to extend this pathlength to distances much greater than a lkm. For cases of long distance optical propagation,
atmospheric turbulence will ultimately limit the maximum achievable data rate. In this paper, we propose a method of
improved signal quality through the use of adaptive optics. In particular, we show work in progress toward a high-speed, small
footprint Adaptive Optics system for horizontal path laser communications. Such a system relies heavily on recent progress
in Micro-Electro- Mechanical Systems (MEMS) deformable mirrors as well as improved communication and computational
components. In this paper we detail two Adaptive Optics approaches for improved through-put, the first is the compensated
receiver (the traditional Adaptive Optics approach), the second is the compensated transmitter/receiver. The second approach
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