Method and device for converting optical frequency

Patent metadata

Field	Value
Publication number	US-9280032-B2
Application number	US-201214114003-A
Country	US
Kind code	B2
Filing date	Apr 23, 2012
Priority date	Apr 28, 2011
Publication date	Mar 8, 2016
Grant date	Mar 8, 2016

Abstract

An optical frequency conversion method and device are provided by which a component other than a desired harmonic component can be eliminated with high precision and an output lightwave with the desired frequency component can be easily extracted even if the frequency of a modulation signal is changed. A plurality of phase control sections ( 101 - 1 to 101 - n ) that respectively generate a plurality of individual modulation signals with different phases from a modulation signal, a plurality of optical single sideband modulation sections (MOD 1 to MODn) that respectively modulate an input lightwave in accordance with the plurality of individual modulation signals, and a plurality of optical phase control sections ( 201 - 1 to 201 - n ) that respectively give optical phase differences to a plurality of lightwaves that are respectively output from the plurality of optical single sideband modulation sections, an output lightwave is generated by multiplexing a plurality of lightwaves that are output from the plurality of optical phase control sections, wherein phase differences among the plurality of individual modulation signals and the optical phase differences are set so that a predetermined harmonic component other than a target frequency in the output lightwave will be eliminated.

First claim

What is claimed is:

1. An optical frequency conversion device which converts a frequency of an input lightwave in accordance with a modulation signal by using a sideband modulation scheme and thereby generates an output lightwave, comprising:
a plurality of phase controllers for respectively generating from the modulation signal a plurality of individual modulation signals with different phases;
a plurality of optical single sideband modulators for respectively modulating the input lightwave in accordance with the plurality of individual modulation signals;
a plurality of optical phase controllers for respectively giving optical phase differences to a plurality of lightwaves that are respectively output from the plurality of optical single sideband modulators; and
a multiplexer for multiplexing a plurality of lightwaves that are output from the plurality of optical phase controllers to generate the output lightwave,
wherein each of the plurality of phase controllers and each of the plurality of optical phase controllers is configured such that phase differences among the plurality of individual modulation signals and the optical phase differences are set so that third or higher predetermined harmonic components other than a target frequency in the output lightwave will be eliminated.

2. The optical frequency conversion device according to claim 1 , wherein the plurality of lightwaves respectively output from the plurality of optical phase controllers have same frequency spectra, and the phase differences among the plurality of individual modulation signals and the optical phase differences are set so that a phase difference of π will be given to the predetermined harmonic components.

3. The optical frequency conversion device according to claim 1 , wherein when n is a number of the plurality of phase control means, f0 is the frequency of the input lightwave, f is a frequency of the modulation signal, and f0+(2m+1)f is a frequency of the predetermined harmonic component, then the phase differences among the plurality of individual modulation signals and the optical phase differences are π/2k+1 and −π/2k+1 (k=1, . . . , n−1), respectively, where n is the smallest integer that is not smaller than log 2(m).

4. The optical frequency conversion device according to claim 1 , wherein the input lightwave is an optical signal with a frequency f0, the modulation signal is an electric signal with a variable frequency f, and the output lightwave is an optical signal with the target frequency of f0+f or f0−f.

5. The optical frequency conversion device according to claim 4 , wherein the plurality of phase controllers change phase control operation points based on the frequency f of the modulation signal.

6. The optical frequency conversion device according to claim 1 , wherein for each of the plurality of optical single sideband modulators, a bias is set so that an optical intensity of an output lightwave of the respective optical single sideband modulator will be the smallest in a state where no individual modulation signal is input to the respective optical single sideband modulator.

7. An optical transmitter that transmits an input optical signal after converting its frequency in accordance with a modulation signal, comprising the optical frequency conversion device according to claim 1 .

Assignees

• Fujisawa Shinsuke
• Nec Corp

Inventors

• Fujisawa Shinsuke

Classifications

• G02F2001/212

  Physics · mapped topic

• H04B10/25 Primary

  Arrangements specific to fibre transmission · CPC title

• G02F2203/50

  Phase-only modulation · CPC title

• G02F2203/58

  Multi-wavelength, e.g. operation of the device at a plurality of wavelengths · CPC title

• H04B10/29

  Repeaters · CPC title