System to control wavelength and method to control wavelength

Patent metadata

Field	Value
Publication number	US-9395504-B2
Application number	US-201414489147-A
Country	US
Kind code	B2
Filing date	Sep 17, 2014
Priority date	Sep 19, 2013
Publication date	Jul 19, 2016
Grant date	Jul 19, 2016

Abstract

A system includes: a splitter to branch an optical signal output by a wavelength-tunable light source into first to third optical signals; a first photodiode to perform an optical electrical conversion of the first optical signal transmitting a first etalon; a second photodiode to perform an optical electrical conversion of the second optical signal transmitting a second etalon, an FSR of the second etalon being identical to that of the first etalon, peak wavelengths of intensity of a transmitted light of the second etalon being different from those of the first etalon; a third photodiode to perform an optical electrical conversion of the third optical signal; and a controller to control the wavelength-tunable light source with use of a coefficient calculated by following formulas (1) or (2), Coefficient=(PD1−A·PD3)/(PD2−B·PD3) (1) and Coefficient=(PD2−B·PD3)/(PD1−A·PD3) (2).

First claim

What is claimed is:

1. A system to control a wavelength comprising:
a splitter configured to branch an optical signal output by a wavelength-tunable light source into a first to a third optical signals;
a first photodiode configured to perform an optical electrical conversion of the first optical signal transmitting a first etalon;
a second photodiode configured to perform an optical electrical conversion of the second optical signal transmitting a second etalon, an FSR of the second etalon being identical to that of the first etalon, peak wavelengths of intensity of a transmitted light of the second etalon being different from those of the first etalon;
a third photodiode configured to perform an optical electrical conversion of the third optical signal; and
a controller configured to control the wavelength-tunable light source with use of a coefficient calculated by following formulas (1) and (2) of which absolute value is smaller,
Coefficient=( PD 1− A·PD 3)/( PD 2− B·PD 3)  (1)

Coefficient=( PD 2− B·PD 3)/( PD 1− A·PD 3)  (2)

wherein:
PD1 is an output of the first photodiode;
PD2 is an output of the second photodiode;
PD3 is an output of the third photodiode;
A is an average of a ratio of PD1 with respect to PD3; and
B is an average of a ratio of PD2 with respect to PD3.

2. The system as claimed in claim 1 , wherein the controller performs a feedback control of the wavelength-tunable light source with use of the formula.

3. The system as claimed in claim 2 , wherein the controller controls the wavelength-tunable light source based on an initial value that is obtained according to configuration information of a wavelength before the feedback control.

4. The system as claimed in claim 3 , wherein the initial value is stored in a table that is made in advance.

5. The system as claimed in claim 1 , wherein the peak wavelengths of the first etalon are different from those of the second etalon within plus-minus 10% of FSR/4 to suppress variation in a differential gain of the formulas.

6. A method to control a wavelength comprising:
branching an optical signal output by a wavelength-tunable light source into a first to a third optical signals;
performing an optical electrical conversion of the first optical signal transmitting a first etalon with a first photodiode;
performing an optical electrical conversion of the second optical signal transmitting a second etalon with a second photodiode, an FSR of the second etalon being identical to that of the first etalon, peak wavelengths of intensity of a transmitted light of the second etalon being different from those of the first etalon;
performing an optical electrical conversion of the third optical signal with a third photodiode; and
controlling the wavelength-tunable light source with use of a coefficient calculated by following formulas (1) and (2) of which absolute value is smaller,
a coefficient=( PD 1− A·PD 3)/( PD 2− B·PD 3)  (1)

a coefficient=( PD 2− B·PD 3)/( PD 1− A·PD 3)  (2)

wherein:
PD1 is an output of the first photodiode;
PD2 is an output of the second photodiode;
PD3 is an output of the third photodiode;
A is an average of a ratio of PD1 with respect to PD3; and
B is an average of a ratio of PD2 with respect to PD3.

7. The method as claimed in claim 6 further comprising performing a feedback control of the wavelength-tunable light source with use of the formula.

8. The method as claimed in claim 7 , wherein the wavelength-tunable light source is controlled based on an initial value that is obtained according to configuration information of a wavelength before the feedback control.

9. The method as claimed in claim 8 , wherein the initial value is stored in a table that is made in advance.

10. The method as claimed in claim 6 , wherein the peak wavelengths of the first etalon are different from those of the second etalon within plus-minus 10% of FSR/4 to suppress variation in a differential gain of the formulas.

11. A system to control a wavelength comprising:
a splitter configured to branch an optical signal output by a wavelength-tunable light source into a first to a third optical signals;
a first photodiode configured to perform an optical electrical conversion of the first optical signal transmitting a first etalon;
a second photodiode configured to perform an optical electrical conversion of the second optical signal transmitting a second etalon, an FSR of the second etalon being identical to that of the first etalon, peak wavelengths of intensity of a transmitted light of the second etalon being different from those of the first etalon;
a third photodiode configured to perform an optical electrical conversion of the third optical signal; and
a controller configured to control the wavelength-tunable light source with use of a coefficient calculated by following one of formulas (1) and (2), wherein a coefficient calculated by following formula (1) is used on a condition that an absolute value of the coefficient is less than an absolute value of a coefficient calculated by following formula (2), and otherwise the coefficient calculated by following formula (2) is used,
Coefficient=( PD 1− A·PD 3)/( PD 2− B·PD 3)  (1)

Coefficient=( PD 2− B·PD 3)/( PD 1− A·PD 3)  (2)

wherein:
PD1 is an output of the first photodiode;
PD2 is an output of the second photodiode;
PD3 is an output of the third photodiode;
A is an average of a ratio of PD1 with respect to PD3; and
B is an average of a ratio of PD2 with respect to PD3.

12. The system as claimed in claim 11 , wherein the controller performs a feedback control of the wavelength-tunable light source with use of the formula.

13. The system as claimed in claim 12 , wherein the controller controls the wavelength-tunable light source based on an initial value that is obtained according to configuration information of a wavelength before the feedback control.

14. The system as claimed in claim 13 , wherein the initial value is stored in a table that is made in advance.

15. The system as claimed in claim 11 , wherein the peak wavelengths of the first etalon are different from those of the second etalon within plus-minus 10% of FSR/4 to suppress variation in a differential gain of the formulas.

Assignees

• Sumitomo Electric Industries
• Nat Inst Of Advanced Ind Scien

Inventors

• Uesaka Katsumi
• Banno Eiichi
• Shoji Hajime
• Matsuura Hiroyuki
• Kuwatsuka Haruhiko
• Tanizawa Ken
• Namiki Shu

Classifications

• G02B6/4215 Primary

  the intermediate optical elements being wavelength selective optical elements, e.g. variable wavelength optical modules or wavelength lockers (G02B6/4246 takes precedence) · CPC title

• G01J2001/4247

  for testing lamps or other light sources · CPC title

• H01S5/0687

  Stabilising the frequency of the laser · CPC title

• G01J1/4257

  applied to monitoring the characteristics of a beam, e.g. laser beam, headlamp beam (monitoring arrangements for lasers in general H01S3/0014) · CPC title