Optical phase multi-level modulation method and apparatus, and error control method

• US 20040141222A1
• Filed: 10/31/2003
• Published: 07/22/2004
• Est. Priority Date: 11/01/2002
• Status: Abandoned Application

• Current Assignee: National Institute of Information and Communications Technology
• Original Assignee: Communications RES Lab IND Admin Institute
• Inventors: Kikuchi, Kazuro, Miyazaki, Tetsuya
• Application Number:
  US10/697,117
• Publication Number:
  US 20040141222A1
• Time in Patent Office: Days
• US Class Current: 359/237
• CPC Class Codes: G02F 1/0121 Operation of devices; Circuit arrangements, not otherwise provided for in this subclass
• CPC Class Codes: G02F 1/212 Mach-Zehnder type
• CPC Class Codes: G02F 2201/16 series; tandem
• CPC Class Codes: H04B 10/505 using external modulation
• CPC Class Codes: H04B 10/5051 using a series, i.e. cascade, combination of modulators
• CPC Class Codes: H04B 10/5053 using a parallel, i.e. shunt, combination of modulators
• CPC Class Codes: H04B 10/5055 using a pre-coder
• CPC Class Codes: H04B 10/548 Phase or frequency modulation
• CPC Class Codes: H04B 2210/003 Devices including multiple stages, e.g., multi-stage optical amplifiers or dispersion compensators

Abstract

A phase modulation method and apparatus use a plurality of phase modulators disposed in series to phase-modulate light from a source laser. Modulation by the phase modulators is used to produce phase shifts in the optical signal, with modulation by the first phase modulator producing phase shifts of 0 degrees or 2φ degrees, and modulation by the n-th phase modulator producing phase shifts of 0 degrees or 2ⁿ×φ degrees. Here, φ degrees is a predetermined phase level and n is an integer than two and not more than the number of phase modulators. The method is also used to detect and control transmission errors.

Claims

1. A phase modulation method comprising:

using a plurality of phase modulators disposed in series to phase modulate light from a source laser,

wherein modulation by a first phase modulator is phase modulation that produces phase shifts of 0 degrees or 2φ

degrees, and

modulation by an n-th phase modulator is phase modulation that produces phase shifts of 0 degrees or 2ⁿ×

φ

degrees, φ

degrees being a predetermined phase level and n an integer that is not less than two and not more than the number of phase modulators.

2. An optical phase multi-level modulation method comprising:

using first and second phase modulators disposed in series to phase modulate a light from a source laser,

wherein modulation by the first phase modulator is modulation by an in-phase component of quadrature modulation, and

modulation by the second phase modulator is modulation by a quadrature component of quadrature modulation.

11. An error control method that detects and controls errors on a bit-by-bit basis, comprising using the optical phase multi-level modulation method according to claim 2 on a sending side to transmit the laser light signal modulated by quadrature modulation in-phase and quadrature components containing some of the same symbols as the respective information signals, and on a receiving side confirms whether or not the logical lev is of the decoded signals are the same.

12. The error control method according to claim 11, in which, in said confirmation, logical levels provided for the quadrature and in-phase components are used to determine whether a state of said components is high (H) or low (L), with a determination only being used if it matches the component determination outcome concerned (H, M or L).

13. The error control method according to claim 12, in which, on a receiving side, symbols included in the in-house and quadrature components that are the same are given different delay times to cancel delay time differences between symbols included in the in-house and quadrature components that are the same.

3. An optical phase multi-level modulation method comprising:

using first and second phase modulators disposed in series to phase modulate a light from a source laser,

wherein modulation by the first phase modulator is modulation that produces phase shifts of 0 degrees or 180 degrees, and

modulation by the second phase modulator is modulation that produces phase shifts of 0 degrees or 90 degrees.

4. An optical phase multi-level modulation method comprising;

using first and second phase modulators disposed in series to phase modulate a light from a source laser,

wherein modulation by the first phase modulator is modulation by an in-phase component of quadrature modulation that produces phase shifts of 0 degrees or 180 degrees, and

modulation by the second phase modulator is modulation by a quadrature component of quadrature modulation that produces phase shifts of 0 degrees or 90 degrees.

5. An optical phase multi-level modulation method comprising:

using first and second phase modulators disposed in series to phase modulate a light from a source laser,

wherein modulation by the first phase modulator is modulation by an in-phase component of quadrature modulation that produces phase shifts of 0 degrees or 90 degrees, and

modulation by the second phase modulator is modulation by a quadrature component of quadrature modulation that produces phase shifts of 0 degrees or 180 degrees.

6. An optical phase multi-level modulation apparatus comprising:

a laser light source and a plurality of phase modulators disposed in a series configuration in which a light from the laser light source is modulated by a first phase modulator that produces phase shifts of 0 degrees or 2φ

degrees, and is modulated by an n-th phase modulator that produces phase shifts of 0 degrees or 2ⁿ×

φ

degrees, φ

degrees being a predetermined phase level and n an integer that is not less than two and not more than the number of phase modulators.

7. An optical phase multi-level modulation apparatus comprising:

a laser light source, first and second phase modulators disposed in series, and means for outputting in-phase and quadrature components of quadrature modulation, in which a light from the laser light source is modulated in the first phase modulator by an in-phase component of quadrature modulation, and is modulated in the second phase modulator by a quadrature component of quadrature modulation.

8. An optical phase multi-level modulation apparatus comprising:

a laser light source, first and second phase modulators disposed in series, and means for outputting in-phase and quadrature components of quadrature modulation, in which light from the laser light source modulated in the first phase modulator is phase-shifted 0 degrees or 180 degrees, and light modulated in the second phase modulator is phase-shifted 0 degrees or 90 degrees.

9. An optical phase multi-level modulation apparatus comprising:

a laser light source, first and second phase modulators disposed in series, and means for outputting in-phase and quadrature components of quadrature modulation, in which a light from the laser light source is modulated in the first phase modulator by an in-phase component of quadrature modulation that produces phase shifts of 0 degrees or 180 degrees, and is modulated in the second phase modulator by a quadrature component of quadrature modulation that produces phase shifts of 0 degrees or 90 degrees.

10. An optical phase multi-level modulation apparatus comprising:

a laser light source, first and second phase modulators disposed in series, and means for outputting in-phase and quadrature components of quadrature modulation, in which a light from the laser light source is modulated in the first phase modulator by an in-phase component of quadrature modulation that produces phase shifts of 0 degrees or 90 degrees, and is modulated in the second phase modulator by a quadrature component of quadrature modulation that produces phase shifts of 0 degree or 180 degrees.