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Title: Remotely-interrogated high data rate free space laser communications link

Abstract

A system and method of remotely extracting information from a communications station by interrogation with a low power beam. Nonlinear phase conjugation of the low power beam results in a high power encoded return beam that automatically tracks the input beam and is corrected for atmospheric distortion. Intracavity nondegenerate four wave mixing is used in a broad area semiconductor laser in the communications station to produce the return beam.

Inventors:
 [1]
  1. Livermore, CA
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
909430
Patent Number(s):
7,224,905
Application Number:
09/827,454
Assignee:
The Regents of the University of California (Oakland, CA) OAK
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
47 OTHER INSTRUMENTATION

Citation Formats

Ruggiero, Anthony J. Remotely-interrogated high data rate free space laser communications link. United States: N. p., 2007. Web.
Ruggiero, Anthony J. Remotely-interrogated high data rate free space laser communications link. United States.
Ruggiero, Anthony J. Tue . "Remotely-interrogated high data rate free space laser communications link". United States. doi:. https://www.osti.gov/servlets/purl/909430.
@article{osti_909430,
title = {Remotely-interrogated high data rate free space laser communications link},
author = {Ruggiero, Anthony J},
abstractNote = {A system and method of remotely extracting information from a communications station by interrogation with a low power beam. Nonlinear phase conjugation of the low power beam results in a high power encoded return beam that automatically tracks the input beam and is corrected for atmospheric distortion. Intracavity nondegenerate four wave mixing is used in a broad area semiconductor laser in the communications station to produce the return beam.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue May 29 00:00:00 EDT 2007},
month = {Tue May 29 00:00:00 EDT 2007}
}

Patent:

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  • Free-space optical (FSO) laser communication systems offer exceptionally wide-bandwidth, secure connections between platforms that cannot other wise be connected via physical means such as optical fiber or cable. However, FSO links are subject to strong channel fading due to atmospheric turbulence and beam pointing errors, limiting practical performance and reliability. We have developed a fade-tolerant architecture based on forward error correcting codes (FECs) combined with delayed, redundant, sub-channels. This redundancy is made feasible though dense wavelength division multiplexing (WDM) and/or high-order M-ary modulation. Experiments and simulations show that error-free communications is feasible even when faced with fades that are tensmore » of milliseconds long. We describe plans for practical implementation of a complete system operating at 2.5 Gbps.« less
  • A Nd:YAG laser is described that operates in a dual functioning cavity with a Ba/sub 2/Na(NbO/sub 3/)/sub 5/ frequency doubling crystal that provides two frequencies of laser radiation, one frequency double the other, to provide a laser beacon beam at a wavelength of approximately 1.06 micrometers and a high data rate beam at a wavelength of approximately 0.53 micrometer.
  • Materials studies as well as general and specific device development were carried out in the InGaAsP system. A comparison was made of three standard methods of evaluating substrate quality by means of dislocation studies. A cause of reduced yield of good wafers, the pullover of melt from one bin to the next, has been analyzed. Difficulties with reproducible zinc acceptor doping have been traced to segregation of zinc in the In/Zn alloy used for the doping source. Using EBIC measurments, the pn junction was shown to drift in location depending on factors not always under control. An analysis of contactmore » structures by SIMS showed that the depth to which the sintered Au/Zn contact penetrates into the structure is typically 0.13 microns, or well within the cap layer and out of the p-type cladding and thus not deleterious to laser performance. The problem of single-mode laser development was investigated and it was shown to be related to the growth habit over four different possible substrate configurations. The fabrication of constricted double heterojunctions, mesa stripe buried heterostructures, and buried heterostructures was discussed, and measurements were presented on the device properties of single-mode buried heterostructure lasers. Results include single spectral line emission at 3 mW and a threshold current of 60 mA.« less
  • Injection lasers of AlGaAs (Lambda(L) approximately 800 nm) have been permanently bonded to single-mode fibers, with power levels up to 600 microwatts being coupled into the fibers. Values over 150 microwatts were consistently obtained under cw operation at room temperature. Very close mechanical alignment tolerances are required to achieve good coupling, with positioning to + or - 1 micrometer being required. This necessitates the use of bonding materials for attaching the fiber to the laser mount that have a high dimensional stability over long time periods, and lasers whose modal patterns do not change with time or operating conditions. Anmore » epoxy provided the best bonding material that we found, although there are indications that suitable low-melting solders can also be used. Laser mode changes with drive current level can alter the observed coupling efficiency significantly.« less
  • A single transmission line interrogated multiple channel data acquisition system is provided in which a plurality of remote station/sensor circuits each monitors a specific process variable and each transmits measurement values over a single transmission line to a master interrogating station when addressed by said master interrogating station. Typically, as many as 330 remote stations may be parallel connected to the transmission line which may exceed 7,000 feet. The interrogation rate is typically 330 stations/second. The master interrogating station samples each station according to a shared, charging transmit-receive cycle. All remote station address signals, all data signals from the remotemore » stations/sensors and all power for all of the remote station/sensors are transmitted via a single continuous terminated coaxial cable. A means is provided for periodically and remotely calibrating all remote sensors for zero and span. A provision is available to remotely disconnect any selected sensor station from the main transmission line.« less