Dispersion compensator and optical transmission system using same

• US 6,731,846 B2
• Filed: 08/30/2001
• Issued: 05/04/2004
• Est. Priority Date: 05/11/2001
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Hosomi, Kazuhiko, Katsuyama, Toshio, Lee, Young-kun, Ojima, Masahiro
• Primary Examiner(s): Healy, Brian
• Application Number:
  US09/941,697
• Publication Number:
  US 20020172456A1
• Time in Patent Office: 978 Days
• Field of Search: 385/123, 385/124, 385/125, 385/126, 385/24, 385/25, 385/26, 385/27, 385/28, 398/81, 398/158
• US Class Current: 385/123
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02B 6/1225 comprising photonic band-gap structures or photonic lattices
• CPC Class Codes: G02B 6/29317 Light guides of the optical fibre type
• CPC Class Codes: G02B 6/29394 Compensating wavelength dispersion G02B6/29376 takes precedence; dispersion compensated optical transmission systems H04B10/2507
• CPC Class Codes: G02B 6/29395 configurable, e.g. tunable or reconfigurable switching G02B6/35
• CPC Class Codes: G02F 1/035 in an optical waveguide structure
• CPC Class Codes: G02F 2202/32 Photonic crystals

Abstract

The present invention aims to provide a dispersion compensator which is ultra small in size and low in cost and capable of controlling dispersion compensating values, and an optical transmission system using the dispersion compensator. A dispersion property of light that propagates through defects in a photonic crystal, is used to compensate for each wavelength dispersion. A dispersion compensator comprises a dispersion-compensating-waveguide array in which a plurality of dispersion compensating waveguides having dispersion compensating values different from one another are placed, a drive unit for driving the dispersion-compensating-waveguide array, and optical fibers for inputting/outputting a light signal. Each of the dispersion compensating waveguides comprises regular waveguides and a waveguide made of defects in photonic crystal. The lengths of the waveguides made of the defects in photonic crystal are changed one by one to make dispersion compensating values different from one another.

Claims

1. The dispersion compensator for compensating for a wavelength dispersion of a transmission medium lying in an optical pulse transmission path, comprising:

at least one dispersion compensating waveguide formed by a photonic crystal in which ununiform elements are introduced into periodic structures of at least two or more types of mediums different in refractive index;

whereby a dispersion property of light that propagates through the ununiform elements of the photonic crystal, is used to compensate for the waveform dispersion,

wherein the ununiform elements of the photonic crystal and the periodic structures lying therearound form coupled microcavities, and the microcavities are used to compensate for the wavelength dispersion.

2. The dispersion compensator for compensating for a wavelength dispersion of a transmission medium lying in an optical pulse transmission path, comprising:

at least one dispersion compensating waveguide formed by a photonic crystal in which ununiform elements are introduced into periodic structures of at least two or more types of mediums different in refractive index;

whereby a dispersion property of light that propagates through the ununiform elements of the photonic crystal, is used to compensate for the waveform dispersion,

wherein the length of an occupied waveguide portion of the photonic crystal in the dispersion compensating waveguide is changed to thereby compensate for the wavelength dispersion.

3. The dispersion compensator for compensating for a wavelength dispersion of a transmission medium lying in an optical pulse transmission path, comprising:

at least one dispersion compensating waveguide formed by a photonic crystal in which ununiform elements are introduced into periodic structures of at least two or more types of mediums different in refractive index;

whereby a dispersion property of light that propagates through the ununiform elements of the photonic crystal, is used to compensate for the waveform dispersion,

wherein a lattice constant of the photonic crystal in the dispersion compensating waveguide is changed to thereby compensate for the wavelength dispersion.

4. A dispersion compensator comprising:

light input signal switching means; and

a plurality of dispersion compensating waveguides which are placed side by side on the same plane and have different wavelength dispersions and which respectively have coupled microcavities;

whereby the dispersion compensating waveguides are selected by the switching means to thereby control a value for compensating for each wavelength dispersion in an optical transmission path.

6. The dispersion compensator according to claim 4, wherein the coupled microcavities are formed by each of photonic crystals in which ununiform elements are respectively introduced in periodic structures of at least two types of mediums different in refractive index.

7. The dispersion compensator according to claim 6, wherein the lengths of occupied waveguide portions of the photonic crystals in the respective dispersion compensating waveguides are rendered different to thereby control values for compensating for the wavelength dispersions.

8. The dispersion compensator according to claim 6, wherein lattice constants of the photonic crystals in the respective dispersion compensating waveguides are rendered different to thereby control values for compensating for the wavelength dispersions.

5. A dispersion compensator, at least comprising:

an input-side optical system;

a waveguide array comprising a plurality of dispersion compensating waveguides respectively having different wavelength dispersions;

a drive unit for driving the waveguide array; and

an output-side optical system,

wherein the dispersion compensating waveguides respectively have coupled microcavities, and

wherein the waveguide array is shifted by the drive unit to thereby select the dispersion compensating waveguide through which an optical pulse passes, whereby the dispersion compensating waveguide controls a value for compensating each wavelength dispersion in an optical transmission path.