CDMA encoder-decoder, CDMA communication system, WDM-CDMA communication system

• US 6,711,313 B2
• Filed: 01/04/2001
• Issued: 03/23/2004
• Est. Priority Date: 01/06/2000
• Status: Expired due to Fees

• Current Assignee: Nippon Telegraph and Telephone Corporation
• Original Assignee: Nippon Telegraph and Telephone Corporation
• Inventors: Kato, Masao, Shibata, Tomohiro, Goh, Takashi, Okamoto, Katsunari, Takiguchi, Koichi
• Primary Examiner(s): Lee, John D.
• Assistant Examiner(s): HAHM, SARAH UH YOUNG
• Application Number:
  US09/753,565
• Publication Number:
  US 20010010739A1
• Time in Patent Office: 1,174 Days
• Field of Search: 385/15, 385/16, 385/24, 385/27, 359/136, 359/140
• US Class Current: 385/15
• CPC Class Codes: G02B 6/12021 Comprising cascaded AWG devices; AWG multipass configuration; Plural AWG devices integrated on a single chip
• CPC Class Codes: G02B 6/2861 using fibre optic delay lines and optical elements associated with them, e.g. for use in signal processing, e.g. filtering delay lines in general H03H, H01P9/00; optical computing devices G06E
• CPC Class Codes: H04J 14/005 Optical Code Multiplex
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems

Abstract

An optical CDMA encoder-decoder is constructed by combining arrayed-waveguide gratings, matrix optical switches, and delay lines, otherwise by combining arrayed-waveguide grating and variable delay lines, thus providing an encoding process that a wavelength change with respect to time in optical pulses. The light includes a wide spectrum band width inserted into a CDMA encoder/decoder and is demultiplexed by arrayed-waveguide gratings. Each wave length according to the demultiplexed spectrum component spreads out in the time region based on delay time differences produced by delay lines having differential optical lengths. Thus, in CDMA, the dependency of wavelengths on delay time can be set arbitrarily.

Claims

1. A CDMA encoder-decoder comprising:

a first arrayed-waveguide grating having a plurality of input and output parts, and inputting and outputting a signal;

a first matrix optical switch having a plurality of input and output parts, the input parts being connected to the output parts of said first arrayed-waveguide grating;

a plurality of delay lines of which ends are connected to the output parts of said first matrix optical switch and of which lengths are different from each other;

a second matrix optical switch having a plurality of input and output parts, the input parts being connected to the other ends of said plurality of delay lines; and

a second arrayed-waveguide grating having a plurality of input and output parts, the input parts being connected to the output parts of said second matrix optical switch, and the output parts outputting the signal.

5. A CDMA communication system comprising:

the CDMA encoder-decoder according to any one of claims 1 to 4,;

encoders and decoders including a plurality of said CDMA encoders and decoders; and

means for multiplexing and demultiplexing light and a means for transmitting light are disposed between said encoders and decoders.

6. The CDMA communication system according to claim 5, wherein said encoders and decoders comprise an arbitrary combination of a plurality of said CDMA encoders and decoders.

7. A WDM-CDMA communication system comprising:

a WDM communication system including the CDMA encoder-decoder according to any one of the claims 1 to 4,;

wherein a plurality of said CDMA encoders and decoders are used for encoding and decoding each of a plurality of signal wavelengths; and

means for multiplexing and demultiplexing light and a means for transmitting light are disposed between said encoders and decoders.

8. The WDM-CDMA communication system according to claim 7, wherein said CDMA encoders and decoders comprise an arbitary combination of a plurality of said CDMA encoders and decoders.

2. A CDMA encoder-decoder comprising:

an arrayed-waveguide grating having a plurality of input and output parts, and inputting and outputting a signal;

a first matrix optical switch having a plurality of input and output parts, the input parts being connected to the output parts of said arrayed-waveguide grating;

a plurality of delay lines of which ends are connected to the output parts of said first matrix optical switches and of which lengths are different from each other; and

a second matrix optical switch having a plurality of input and output parts, the input parts being connected to the other ends of said delay lines;

wherein the output parts of said second matrix optical switch are connected to either the input parts or output parts of said arrayed-waveguide grating.

3. A CDMA encoder-decoder comprising:

an arrayed-waveguide grating having a plurality of input and output parts, and inputting and outputting a signal;

a matrix optical switch having a plurality of input and output parts, the input parts being connected to the output parts of said arrayed-waveguide grating; and

a plurality of delay lines of which ends are connected to the output parts of said matrix optical switch and of which lengths are different from each other;

wherein the other ends of said delay lines are connected to either the input parts or output parts of said matrix optical switch; and

the connection side parts of said matrix optical switch that have not been used for the connection to the other ends of said delay lines are connected to either the input parts or output parts of said arrayed-waveguide grating.

4. A CDMA encoder-decoder comprising:

an arrayed-waveguide grating having a plurality of input and output parts, and inputting and outputting a signal;

a matrix optical switch having a plurality of input and output parts, the input parts being connected to the output parts of said arrayed-waveguide grating;

a plurality of delay lines of which ends are connected to the output parts of said matrix optical switch and of which lengths are different from each other; and

optical reflectors connected to the other ends of said delay lines.

9. A CDMA encoder-decoder comprising:

a first arrayed-waveguide grating having a plurality of input and output parts, and inputting and outputting a signal;

a plurality of variable delay lines of which input parts are connected to the output parts of said first arrayed-waveguide grating; and

a second arrayed-waveguide grating having a plurality of input and output parts, the input parts being connected to the output parts of said variable delay lines;

wherein said variable delay lines comprise one asymmetrical Mach-Zehnder interferometer or cascaded asymmetrical Mach-Zehnder interferometers in series having the same optical path length differences.

10. A CDMA encoder-decoder comprising:

a first arrayed-waveguide grating having a plurality of input and output parts, and inputting and outputting a signal;

a plurality of variable delay lines of which input parts are connected to the output parts of said first arrayed-waveguide grating; and

a second arrayed-waveguide grating having a plurality of input and output parts, the input parts being connected to the output parts of said variable delay lines;

wherein said variable delay lines comprise cascaded asymmetrical Mach-Zehnder interferometers in series and at least one of said asymmetrical Mach-Zehnder interferometers has an optical path length difference different from those of the others.

11. The CDMA encoder-decoder according to claim 10,

wherein K, an integer equal to or more than two, asymmetrical Mach-Zehnder interferometers have optical path length differences which are 2¹, 2², . . . , and 2^{K− 1} times the minimum optical path length difference.

12. A CDMA encoder-decoder comprising:

a first arrayed-waveguide grating having a plurality of input and output parts, and inputting and outputting a signal;

a plurality of variable delay lines of which input parts are connected to the output parts of said first arrayed-wave guide grating; and

a second arrayed-waveguide grating having a plurality of input and output parts, the input parts being connected to the output parts of said variable delay lines;

wherein said variable delay lines comprise a multiplexer and a demultiplexer;

said multiplexer and demultiplexer are connected by a plurality of variable delay lines with different lengths, and

an optical switch is disclosed on each of said plurality of delay lines.

13. A CDMA encoder-decoder comprising:

a first arrayed-waveguide grating having a plurality of input and output parts, and inputting and outputting a signal;

a plurality of variable delay lines of which input parts are connected to the output parts of said first arrayed-waveguide grating; and

a second arrayed-waveguide grating having a plurality of input and output parts, the input parts being connected to the output parts of said variable delay lines;

wherein said variable delay lines comprise as many as M, an integer equal to or more than two, coupling-coefficient-variable directional couplers that connect a first single waveguide to as many as M waveguides at as many as M different positions; and

said M waveguides are merged into a second single output waveguide by an optical multiplexer after being coupled with said first single waveguide.

14. A CDMA encoder decoder comprising:

an arrayed-wave guide grating having a plurality of input and output part, and inputting and outputting a signal; and

a plurality of variable delay lines of which input parts are connected to the output parts of said arrayed-wave guide grating;

wherein the output parts of said variable delay lines are connected to either the input parts or output parts of said arrayed-waveguide grating,

wherein said variable delay lines comprise one asymmetrical Mach-Zehnder interferometer or cascaded asymmetrical Mach-Zehnder interferometers in series having the same optical path length differences.

15. A CDMA encoder-decoder comprising:

an arrayed-waveguide grating having a plurality of input and output parts, and inputting and outputting a signal; and

a plurality of variable delay lines of which input parts are connected to the output parts of said arrayed-waveguide grating;

wherein the output part of said variable delay lines are connected to either the input parts or output parts of said arrayed-waveguide grating,

wherein said variable delay lines comprise cascaded asymmetrical Mach-Zehnder interferometers in series and at least one of said asymmetrical Mach-Zehnder interferometers has an optical path length difference different from those of the others.

16. The CDMA encoder-decoder according to claim 15,

wherein K, an integer equal to or more than two, asymmetrical Mach-Zehnder interferometers have optical path length differences which are 2¹, 2², . . . , and 2^{K− 1} times the minimum optical path length difference.

17. A CDMA encoder-decoder comprising:

an arrayed-waveguide grating having a plurality of input and output parts, and inputting and outputting a signal; and

a plurality of variable delay lines of which input parts are connected to the output parts of said arrayed-waveguide grating;

wherein the output parts of said variable delay lines are connected to either the input parts or output parts of said arrayed-waveguide grating,

wherein said variable delay lines comprise a multiplexer and a demultiplexer;

said multiplexer and demultiplexer are connected by a plurality of variable delay lines with different lengths, and

an optical switch is disposed on each of said plurality of delay lines.

18. A CDMA encoder-decoder comprising:

an arrayed-waveguide rating having a plurality of input and output parts, and inputting a signal; and

delay lines of which input parts are connected to the output parts arrayed waveguide grating;

wherein the output parts of said variable delay lines are connected to either the input parts or output parts of said arrayed-waveguide grating,

wherein said variable delay lines comprise as many as M, an integer equal to or more than two, coupling-coefficient-variable directional couplers that connect a first single waveguide to as many as M waveguides at as many as M different positions; and

said M waveguides are merged into a second single output waveguide by an optical multiplexer after being coupled with said first single waveguide.

19. A CDMA encoder-decoder comprising:

an arrayed-waveguide grating having a plurality of input and output parts, and inputting and outputting a signal;

a plurality of variable delay lines of which input parts are connected to the output parts of said arrayed-waveguide grating; and

optical reflectors connected to the output parts of said variable delay lines,

wherein said variable delay lines comprise one asymmetrical Mach-Zehnder interferometer or cascaded asymmetrical Mach-Zehnder interferometers in series having the same optical path length differences,

wherein each of said optical reflectors comprises a loop-form waveguide which is formed by connecting two portions of one waveguide at one position so that these portions are arranged close to each other, a grating, or a waveguide having a metal or a dielectric multilayered film at its end.

20. A CDMA encoder-decoder comprising:

an arrayed-waveguide grating having a plurality of input and output parts, and inputting and outputting a signal;

a plurality of variable delay lines of which input parts are connected to the output parts of said arrayed-waveguide grating; and

optical reflectors connected to the output parts of said variable delay lines,

wherein said variable delay lines comprise cascaded asymmetrical Mach-Zehnder interferometers in series and at least one of said asymmetrical Mach-Zehnder interferometers has an optical path length difference different from those of the others,

wherein each of said optical reflectors comprises a loop-form waveguide which is formed by connecting two portions of one waveguide at one position so that these portions are arranged close to each other, a grating, or a waveguide having a metal or a dielectric multilayered film at its end.

21. The CDMA encoder-decoder according to claim 20, wherein said K, an integer equal to or more than two, asymmetrical Mach-Zehnder interferometers have optical path length differences which are 2¹, 2², . . . , and 2^K−

1 times the minimum optical path length difference.

22. A CDMA encoder-decoder comprising:

an arrayed-waveguide grating having a plurality of input and output parts, and inputting and outputting a signal;

a plurality of variable delay lines of which input parts are connected to the output parts of said arrayed-waveguide grating; and

optical reflectors connected to the output parts of said variable delay lines, wherein said variable delay lines, comprise a multiplexer and a demultiplexer;

said multiplexer and demultiplexer are connected by a plurality of variable delay lines with different lengths,

an optical switch is disposed on each of said plurality of delay lines,

wherein each of said optical reflectors comprises a loop-form waveguide which is formed by connecting two portions of one waveguide at one position so that these portions are arranged close to each other, a grating, or a waveguide having a metal or a dielectric multilayered film at its end.

23. A CDMA encoder-decoder comprising:

an arrayed-waveguide grating having a plurality of input and output parts, and inputting and outputting a signal;

a plurality of variable delay lines of which input parts are connected to the output parts of said arrayed-waveguide grating; and

optical reflectors connected to the output parts of said variable delay lines,

wherein said variable delay lines comprise as many as M, an integer equal to or more than two, coupling-coefficient-variable directional couplers that connect a first single waveguide to as many as M waveguides at as many as M different positions; and

said M waveguides are merged into a second single output waveguide by an optical multiplexer after being coupled with said first single waveguide,

wherein each of said optical reflectors comprises a loop-form waveguide which is formed by connecting two portions of one waveguide at one position so that these portions are arranged close to each other, a grating, or a waveguide having a metal or a dielectric multilayered film at its end.