Dispersion-free optical filters

Details Dispersion-free optical filters Dispersion-free optical filters

2001-05-03

2004-04-13

Lee, John D. (Department: 2874)

Optical waveguides

With optical coupler

Particular coupling function

C385S015000, C359S015000, C359S890000

Reexamination Certificate

active

06721477

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to optical filters, and in particular to dispersion-free optical filters for use as interleavers.
BACKGROUND OF THE INVENTION
In dense wavelength division multiplexing (DWDM) optical telecommunications systems, it is advantageous to provide a very narrow width optical filter, which isolates individual transmission channels without distorting the information being transmitted. Accordingly, the optical filter must have a flat-top intensity response and no chromatic dispersion in the pass band. These two conditions guarantee that the filter will not distort the signal either in intensity or in phase.
The first condition, i.e. flat-top intensity response, is well known and has been achieved through various technologies, such as thin film filters, fiber Bragg gratings, coupled resonant cavities, and lattice filters. However, the second condition, i.e. no chromatic dispersion, (or equivalently having a linear phase response in the pass band) is harder to achieve for optical filters, especially when combined with the flat-top requirement. Resonant interleavers have an inherently high dispersion, and any dispersion compensation, which would only be partial, is very difficult to achieve,
It is an object of the present invention to disclose practical ways of realizing optical filters with substantially no chromatic dispersion, apart from the material induced dispersion, regardless of the intensity profile of the optical filter. Applications can be envisaged for any type of optical filter, including flat-top filters and interleavers.
SUMMARY OF THE INVENTION
Accordingly the present invention relates to a cascaded optical filter defined by transfer function H
T
(f) comprising:
a first optical filtering means defined by transfer function of H
1
(f); and
a second optical filtering means, optically coupled to the first optical filtering means, defined by transfer function H
2
(f);
wherein the transfer function of the second optical filtering means H
2
(f) complex conjugate of the transfer function of the first optical filtering means H
1
*(f);
whereby H
T
(f)=H
1
(f)×H
2
(f)=H
1
(f)×H
1
*(f).


REFERENCES:
patent: 4343969 (1982-08-01), Kellett
patent: 5216529 (1993-06-01), Paek et al.
patent: 5694233 (1997-12-01), Wu et al.
patent: 2003/0161579 (2003-08-01), Yan et al.
patent: 1 136 857 (2001-09-01), None
patent: 60-428 (1985-01-01), None
patent: 60-429 (1985-01-01), None
Kaname Jinguji et al., “Synthesis of Coherent Two-Port Lattice-Form Optical delay-Line Circuit”, Journal of Lightwave Technology, IEEE, New York, vol. 13, No. 1, Jan. 1995, pp. 73-82.
Christian Scheerer, “Phase Distortions in Optical Transmission Systems”, Frequenz, Schiele & Schon GmbH, Berlin, DE, vol. 54, No. 1-2, Jan. 2000, pp. 42-46.

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