Polarization multiplexing optical transmitter and operation control method

Patent metadata

Field	Value
Publication number	US-9419744-B2
Application number	US-201314418286-A
Country	US
Kind code	B2
Filing date	May 7, 2013
Priority date	Aug 1, 2012
Publication date	Aug 16, 2016
Grant date	Aug 16, 2016

Abstract

A polarization multiplexing optical transmitter of the present invention includes frequency dividing means ( 21 ) that performs frequency dividing on a clock signal having a Baud rate frequency, phase modulation means ( 8 ) that performs phase modulation on a light signal in accordance with the clock signal having undergone the frequency dividing, branching means ( 2 ) that branches the phase-modulated light into two light signals, delay means ( 10 ) that delays one branched light signal relative to the other branched light signal to generate light signals having phases inverted relative to each other, and polarization multiplexing means ( 5 ) that synthesizes the generated signals lights with orthogonal polarizations to generate a polarization multiplexed signal. Hence, the polarization multiplexing optical transmitter that can further improve the signal quality can be accomplished.

First claim

The invention claimed is:

1. A polarization multiplexing optical transmitter comprising:
a frequency dividing unit that performs frequency dividing on a clock signal having a Baud rate frequency;
a phase modulation unit that performs phase modulation on a light signal in accordance with the clock signal having undergone the frequency dividing;
a branching unit that branches the phase-modulated light signal into two branched light signals with polarizations orthogonal to each other;
a delay unit that delays one branched light signal relative to the other branched light signal to generate light signals having phases inverted relative to each other and polarizations orthogonal to each other; and
a polarization multiplexing unit that combines the generated light signals with phases inverted relative to each other and polarizations orthogonal to each other, to generate a polarization multiplexed signal.

2. The polarization multiplexing optical transmitter according to claim 1 , wherein:
the frequency dividing unit divides frequency of the clock signal having the Baud rate frequency to be half in frequency; and
the delay unit delays the one branched light signal relative to the other branched light signal by a cycle of the clock signal having the Baud rate frequency.

3. A polarization multiplexing optical transmitter comprising:
a frequency dividing unit that performs frequency dividing on a clock signal having a Baud rate frequency;
a phase modulation and delay unit that
performs phase modulation on two light signals having polarizations orthogonal to each other and having a same wavelength, in accordance with the clock signal having undergone the frequency dividing, and
delays one phase-modulated light signal relative to the other phase-modulated light signal to generate light signals having phases inverted relative to each other and polarizations orthogonal to each other; and

a polarization multiplexing unit that combines the generated light signals with phases inverted relative to each other and polarizations orthogonal to each other, to generate a polarization multiplexed signal.

4. The polarization multiplexing optical transmitter according to claim 3 , wherein the phase modulation and delay unit comprises:
a branching unit that branches the clock signal having undergone the frequency dividing into a first branched clock signal and a second branched clock signal; and
a delay unit that delays the first branched clock signal relative to the second branched clock signal;
wherein the phase modulation and delay unit is configured to perform phase modulation on the one light signal in accordance with the first branched clock signal, and perform phase modulation on the other light signal in accordance with the second branched clock signal, to generate the light signals having phases inverted relative to each other.

5. The polarization multiplexing optical transmitter according to claim 3 , wherein:
the frequency dividing unit divides frequency of the clock signal having the Baud rate frequency to be half in frequency; and
the phase modulation and delay unit delays the one phase-modulated light signal relative to the other phase-modulated light signal by a cycle of the clock signal having the Baud rate frequency.

6. An operation control method for a polarization multiplexing optical transmitter, the method comprising:
a frequency dividing step for performing frequency dividing on a clock signal having a Baud rate frequency;
a phase modulation step for performing phase modulation on a light signal in accordance with the clock signal having undergone the frequency dividing;
a branching step for branching the phase-modulated light signal into two branched light signals with polarizations orthogonal to each other;
a delay step for delaying one branched light signal relative to the other branched light signal to generate light signals having phases inverted relative to each other and polarizations orthogonal to each other; and
a polarization multiplexing step for combining the generated light signals with phases inverted relative to each other and polarizations orthogonal to each other, to generate a polarization multiplexed signal.

7. The operation control method according to claim 6 , wherein:
the frequency dividing step divides frequency of the clock signal having the Baud rate frequency to be half in frequency; and
the delay step delays the one branched light signal relative to the other branched light signal by a cycle of the clock signal having the Baud rate frequency.

Assignees

• Nec Corp

Inventors

• Inada Yoshihisa

Classifications

• H04J14/04

  Mode multiplex systems · CPC title

• H04B10/532

  Polarisation modulation · CPC title

• H04J14/06 Primary

  Polarisation multiplex systems · CPC title

• H04B10/548

  Phase or frequency modulation · CPC title

• H04B10/255

  Self-phase modulation [SPM] · CPC title