Electromagnetically generated, high-dielectric tube forms a waveguide which retains the electromagnetic energy within the beam, the trapped beam establishes an optical frequency waveguide appropriate for its own conduction with minimum diffraction loss

Chiao, R. Y.

Townes, C. H.

English

NASA Technical Reports Server

December 1969
	 Brief 69-10746 
[I:	 NASA TECH BRIEF 
- ------------- 	 --.,	
-.-. 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information; Springfield, Virginia 22151. 
-	 ,..	 -	 .	 . 
Optical Frequency Waveguide and Ion Transmission System 
Laser Beam in 
Self-Generated 
Waveguide	
Partition 
Laser	
. j Rec&veri #1 
Laser Beam	 Pipe	
Beamsplitter 
fl
Receiver #2 
Optical Frequency Waveg uide 
A self-generating, optical frequency waveguide is 
proposed for improved communications, fashioning 
of materials, and surgical operations. The basis of the 
invention is diffractionless transmission of electro-
magnetic radiation by formation of a dielectric wave-
guide between the source and receiver. 
An electromagnetic beam of optical frequency of suf-
ficient power and correct diameter can produce its own 
dielectric waveguide and is capable of propagation 
through a dielectric medium with minimum refraction 
loss due to its ability to confine its rays of energy. 
This occurs in materials in which the dielectric content 
increases with field intensity and is homogeneous in 
the absence of electromagnetic radiation.
In these materials, a high-energy electromagnetic 
beam can produce a tube of material with a higher 
dielectric constant in a shape and diameter correspond-
ing to the beam. Divergent rays within the beam will 
be internally reflected at the edge of this tube (at the 
transition point from high to low dielectric constant). 
Thus, this self-generated, high-dielectric tube forms a 
waveguide which retains the electromagnetic energy 
within the beam. 
The trapped beam establishes a waveguide of ap-
propriate characteristics for its own conduction; weak 
waves of higher frequency are conducted but not those 
of lower frequency. To a first-order approximation, 
the dielectric properties of the waveguide are undis-
(continued overleaf) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
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turbed by such a wave, provided that the beat fre-
quency between it and the initial wave is too high for 
the dielectric to respond. 
Power density of the beam and critical power for 
self-trapping are distinctly different and separable. 
Critical power can be preselected relative to wave-
length, beam diameter, etc., according to the required 
function of the beam. Thus for cutting or forming 
operations high power densities are required, while 
for long-range transmission, low-level power density 
should be maintained to minimize losses due to heat-
ing. A steel pipe filled with carbon dioxide is recom-
mended as the basic structure, because the gas has a 
favorable index of refraction. However, the critical 
power for beam-entrapment is a function of gas pres-
sure. The power required for the self-trapping at one 
atmosphere pressure is one hundred times greater 
than the power required at one hundred atmospheres. 
Thus the pressure used to fill the pipe should be modi-
fied to suit particular applications, depending upon 
the power of the beam to be used.
Note: 
No additional documentation is available. Specific 
questions, however, may be referred to: 
Technology Utilization Officer 
Headquarters 
National Aeronautics 
and Space .Administration 
Washington, D.C. 20546 
Reference: B69-10746 
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA, Code 
GP, Washington, D.C. 20546. 
Source C. H. Townes, R. Y. Chiao.

and E. M. Garmire of

Massachusetts Institute of Technology

under contract to

NASA Headquarters 
(HQN- 10541)
I 
. 
., 
. 
Brief 69-10746	 Category 01


Optical frequency waveguide and ion transmission system

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