Optical: systems and elements – Deflection using a moving element – Using a periodically moving element
Reexamination Certificate
2001-08-14
2003-05-13
Pascal, Leslie (Department: 2633)
Optical: systems and elements
Deflection using a moving element
Using a periodically moving element
C359S199200, C359S199200, C359S199200, C359S199200, C359S199200, C359S199200
Reexamination Certificate
active
06563622
ABSTRACT:
TECHNICAL FIELD
The present invention relates to fiber-optic transmission and to computer routers and servers, and, more particularly to a method and apparatus for a very high bandwidth analog or digital communications band source for use in fiber-optic data transmission applications or as very high bandwidth modulators for computer routers and servers.
BACKGROUND OF THE INVENTION
At present, one of the important communications bands for optical fiber is at a wavelength of about 1.5 &mgr;m. To get the most effective use of the bandwidth available in this band, a combination of direct modulation of 1.5 &mgr;m sources and wavelength division multiplexing (WDM) are typically employed. The maximum modulation rate for standard products are about 10 Gb/s and there are now some special modulators available at about 40 Gb/s. It appears that the approaches used to get to 40 Gb/s will not be scalable to much higher frequencies for a number of reasons. So by using different optical wavelengths (i.e., WDM technology) together with high modulation rates (e.g., 10 Gb/s to 40 Gb/s as available today), a fair degree of the available fiber bandwidth can be used. However this approach has a number of drawbacks including: the requirement for multiplexing in a format which does not lend itself to packet switching (as is typical on the internet), multiplexing in a format which presents significant challenges for repeaters (as are required for long haul transmission), the cost of WDM systems tends to scale with the required throughput (this is contrary to the economic need for the cost to decrease as the usage increases), and there is a desire to use even more of the available bandwidth. Consequently it is desirable to be able to operate at still higher modulation rates.
Many of these issues also exist for data communications associated with future computer systems that will require greater than 40 GHz modulators, which is the upper range of today's optical modulator technologies (e.g., integrated optics and electro-absorptive modulators).
SUMMARY OF THE INVENTION
These and other drawbacks and deficiencies of the prior art are overcome or alleviated by the present invention. A need exists to increase the amount of analog or digital information that can be transmitted over a communications channel such as a given optical fiber in fiber-optic communication applications or in future computer systems that will need to feed high data rate switches. Therefore, it would be desirable to have a method to directly modulate a 1.5 &mgr;m wavelength source at higher rates. In the interest of clarity, the present invention is described with respect to the 1.5 &mgr;m wavelength band, however the techniques described herein could also be employed at other fiber bands. WDM, or Dense Wavelength Division Multiplexing (DWDM), could then be applied to the result, with certain overlap restrictions.
A communications transmission system or light modulating system comprises a first source for providing terahertz (THz) radiation, a very large bandwidth modulator that imposes very large bandwidth information on the THz radiation, a second shorter wavelength source having an output wavelength suitable for transmission over fiber optic transmission systems, and a nonlinear optical conversion subsystem which imposes the THz modulated radiation onto the shorter wavelength transmission radiation to generate radiation suitable for transmission over a fiber optic communication system having the very large bandwidth information imposed on the resulting radiation to be transmitted through the optical fiber communication system or to ultra-fast switches used in ultra-fast computer servers and/or routers.
A method of increasing the amount of information transmitted over a communications channel and increasing the extinction ratio of a data transmission system comprises modulating a carrier signal having a first prescribed frequency with an information signal having a prescribed first bandwidth, generating thereby a modulated carrier signal having a second prescribed bandwidth; and mixing a transmission signal having a second prescribed frequency with the modulated carrier signal, generating thereby a converted transmission signal having a third prescribed bandwidth.
The above-discussed and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description and drawings.
REFERENCES:
patent: 4553265 (1985-11-01), Clifton et al.
patent: 5379309 (1995-01-01), Logan, Jr.
patent: 5710651 (1998-01-01), Logan, Jr.
patent: 5768002 (1998-06-01), Puzey
patent: 5796506 (1998-08-01), Tsai
patent: 5822103 (1998-10-01), Boroson
patent: 5886809 (1999-03-01), Puzey
patent: 5896211 (1999-04-01), Watanabe
patent: 6031644 (2000-02-01), Utsumi
patent: 6043920 (2000-03-01), Leopold et al.
patent: 6046486 (2000-04-01), McNamara et al.
patent: 6115162 (2000-09-01), Graves et al.
patent: 6118566 (2000-09-01), Price
patent: 6172782 (2001-01-01), Kobayashi
patent: 6172790 (2001-01-01), Tiemann et al.
patent: 6359716 (2002-03-01), Taylor
patent: 6366377 (2002-04-01), Tajima
Dissertation by David Stephen Kurtz, “Sideband Generation For Submillimeter Wave Applications”, May, 2000 Article published in The Wall Street Journal, Jun. 25, 2001 entitled “World's Fastest Silicon Transistor”.
Article published in Applied Phys Lett. vol. 21, No. 11, Dec. 1, 1972 entitled “Phase matched sumillimeter wave generation by difference-frequency mixing in ZnGeP2”.
PCT Written Opinion Under Rule 66 for International application No. PCT/US01/25358, International filing date Aug. 13, 2001.
Tetsuo Taniuchi, Jun-ichi Shikata & Hiromasa Ito “Continuously tunable THz-wave generation from GaP crystal by difference frequency mixing with dual-wavelength KTP-OPO”, Darmstadt University GMM of Technology ITG p. 1 & 2.
Eric R. Mueller, William E. Robotham, Jr., Richard P. Meisner, Richard A. Hart, John Kennedy and Leona A. Newman, “2.5 THZ Laser Local Oscillator For The EOS Chem 1 Satellite”, Published in the Proceedings of the Ninth International Symposium on Space Terahertz Technology, p. 563 (1998) 12 pages.
Eric R. Mueller and Jerry Waldman, “Power and Spatial Mode Measurements of Sideband Generated, Spatially Filtered Bubmillimeter Radiation” IEEE Tranactions On Microwave Theory and Techniques, vol. 42, No. 10, Oct., 1994 1 page.
David S. Kurtz, Jeffrey L. Hesler et al, “Millimeter-Wave Sideband Generation Using Varactor Phase Modulators” IEEE Microwave and Guided Wave Letters, vol. 10, No. 6, Jun. 2000, pp. 245-247.
O. Tudisco “Broad Band Far Infrared Fabry-Perot With Variable Finesse”, International Journal of Infrared and Millimeter Waves, vol. 9, No. 11, 1988, pp. 41-53.
Q. Chen and Zhiping Jiang, “Near-field terahertz imaging with a dynamic aperture” Optics Letters, vol. 25, No. 15, Aug. 1, 2000, pp. 1122-1124.
P.Y. Han and M. Tani “Use of the organic crystal DAST for terahertz beam applictions” Optics Letters, vol. 25, No. 9, May 1, 2000, pp. 675-677.
DeMaria Anthony J.
Mueller Eric R.
Cantor & Colburn LLP
Pascal Leslie
Phan Hanh
TeraBit Communications, L.L.C.
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