Optical: systems and elements – Optical frequency converter – Dielectric optical waveguide type
Reexamination Certificate
2000-07-07
2002-08-20
Lee, John D. (Department: 2874)
Optical: systems and elements
Optical frequency converter
Dielectric optical waveguide type
C359S326000, C385S122000
Reexamination Certificate
active
06437905
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to the field of optical communications and in particular to a method and apparatus for providing optical wavelength conversion employing cross phase modulation (XPM).
BACKGROUND OF THE INVENTION
All optical wavelength converters which operate at speeds beyond the limits of electronic devices will be essential components in future Wavelength-Division-Multiplexed (WDM) networks. As was shown in a paper entitled “Wavelength Conversion at 10 GBit/s Using a Semiconductor Optical Amplifier” which appeared in Photon Technol. Lett., 5, (11), pp. 1300-1303, (1993), J.M.Weisenfeld demonstrated all optical wavelength conversion using semiconductor optical amplifier (SOA) devices exploiting cross gain modulation (XGM) as well as cross phase modulation (XPM). As shown therein, in the XGM scheme a strong input signal and a cw signal are introduced into a nonlinear element. The input signal is used to saturate the gain of the nonlinear element and thereby modulates the cw signal carrying the new wavelength. In the XPM scheme, a strong input signal is used to modulate both the phase and intensity of a second signal. The modulation of this second signal is then exploited in an interferometric configuration for redirecting the signal from one output to an other.
Different interferometric configurations have been proposed. Some are based on Michaelson (MI), others are based on Mach-Zehnder interferometer (MZI) configurations with the nonlinear elements on one or both branches of the interferometer arms. (See, e.g., K. Tajima, “All Optical Switch with Switch Off Time Unrestricted by Carrier Lifetime; Jpn. J. Appl, Phys. Vol., 32, No. 12A, pp. L1746-1749; December 1993; K. E. Stubkjaer, T. Durhuus, B. Mikkelsen, C. Joergensen, R. J. Pedersen, C. Braagaard, M.Vaa, S. L. Danielsen, P.Doussiere, G. Garabedian, C. Graver, A. Jourdan, J. Jacquet, D. Leclerc, M. Erman, and M. Klenk, “Optical Wavelength Converters”Proc. European Conf. on Opt. Communication, Firence, Italy, Vol., 2, 635-642, September 1994; J.M.Weisenfeld, “Wavelength Conversion for Optical Networks”, Second Optoelectronic & Communications Conference (OECC97), Technical Digest, pp. 426-427, July 1997. Recent developments include hybrid wavelength converters, using only a single SOA followed by a delay-interference section, formed by a calcite crystal. (See, Y. Ueno, S. Nakamura, K. Tajima, S. Kitamura”, “3.8 THz Wavelength Conversion of Picosecond Pulses Using a Semiconductor Delayed-Interference Signal-Wavelength Converter (DISC)”, Photon. Technol. Letters, Vol., 10, No. 3, March 1998; Y. Ueno, K. Tajima, “Wavelength Converter”, EP 0 875 782 A2.
Despite these advances however, these delay interference wavelength converter schemes is hybrid in nature and their operation is fairly limited.
SUMMARY OF THE INVENTION
We have developed an integrated wavelength converter with a monolithically integrated delay loop in a delayed interference configuration that needs only one SOA, only one in and one output fiber. Unlike prior-art hybrid wavelength converters, our inventive device has a monolithically integrated delay loop utilizing an asymmetric splitting ratio.
REFERENCES:
patent: 5721637 (1998-02-01), Simon et al.
patent: 6256137 (2001-07-01), Hironishi
patent: 6282015 (2001-08-01), Ueno et al.
patent: 6323992 (2001-11-01), Ueno
patent: 0 875 782 (1998-04-01), None
Leuthold et al, “Compact and Fully Packaged Wavelength Converter with Integrated Delay Loop for 40 Gbit/s RZ Signals”, Optical Fiber Communication Conference 2000, vol. 4, pp. 218-220, Mar. 2000.*
Leuthold et al, “100 Gbit/s All-Optical Wavelength Conversion With Integrated SOA Delayed-Interference Configuration”, Electronics Letters, vol. 36, No. 13, pp. 1129-1130, Jun. 22, 2000.*
J. M. Weisenfeld, “Wavelength Conversion at 10 Gbit/s Using a Semiconductor Optical Amplifier”,Photon Technol. Lett., 5, (11), pp. 1300-1303 (1993)(Nov.).
K. Tajima, “All Optical Switch With Switch-Off Time Unrestricted by Carrier Lifetime”,Jpn. J. Appl., Phys., vol. 32, No. 12A, pp. L1746-1749; Dec. 1993.
K. E. Stubhkjaer et al, “Optical Wavelength Converters”,Proc. European Conf. on Opt. Communication, Firence, Italy, vol. 2, pp. 635-642, Sep. 1994.
J. M. Weisenfeld, “Wavelength Conversion for Optical Networks”, Second Optoelectronic and Communications Conference (OECC '97), Technical Digest, pp. 426-427, Jul. 1997.
Y Ueno et al, “3.8-THz Wavelength Conversion of Picosecond Pulses Using a Semiconductor Delayed-Interference Signal-Wavelength Converter (DISC)”,Phton. Technol. Letters, vol. 10, No. 3, Mar. 1998, pp. 346-348.
Joyner Charles H
Leuthold Jurg
Brosemer Jeffery J.
Freedman Barry H.
Lee John D.
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