Optical multiplexing circuit and optical source

Patent metadata

Field	Value
Publication number	US-11768342-B2
Application number	US-202017917034-A
Country	US
Kind code	B2
Filing date	May 18, 2020
Priority date	May 18, 2020
Publication date	Sep 26, 2023
Grant date	Sep 26, 2023

Abstract

In a conventional RGB coupler, the split ratio largely depends on the wavelength. The split ratio of R and the split ratios of G and B are non-uniform because R has a wavelength far from those of G and B. Accordingly, a video display device needs to have the monitoring detection value corrected, making it difficult to use the monitoring function. A light combining circuit and a light source of this disclosure include a first splitting unit for splitting R wavelength light and a second splitting unit for splitting G and B combined light. They split monochromatic light of R and combined light of G and B, independently. G and B light from an LD are first combined by a preliminary wave-combining unit before being split. The split lights of each wavelength are combined by a main wave-combining unit, outputting RGB combined light. Each split light from the two splitting units is detected by a single PD.

First claim

The invention claimed is:

1. A light combining circuit comprising:
a first splitting unit for splitting first wavelength light;
a preliminary wave-combining unit for combining second wavelength light and third wavelength light;
a second splitting unit for splitting the combined second wavelength light and third wavelength light;
a main wave-combining unit for combining first split light from the first splitting unit and first split light from the second splitting unit;
an output waveguide for outputting the combined light from the main wave-combining unit;
a first monitoring waveguide for outputting second split light from the first splitting unit; and
a second monitoring waveguide for outputting second split light from the second splitting unit.

2. The light combining circuit according to claim 1 , wherein
the first and second monitoring waveguides include respective terminations juxtaposed close to each other.

3. The light combining circuit according to claim 2 , further comprising:
a monitoring wave-combining unit disposed in the middle of the first monitoring waveguide, the monitoring wave-combining unit having the same configuration as the main wave--combining unit.

4. The light combining circuit according to claim 2 , wherein
the output waveguide has a termination at a position shifted from the extension in the guided wave direction from the output point of the main wave-combining unit.

5. The light combining circuit according to claim 2 , wherein
the first and second monitoring waveguides are bent waveguides for optical path conversion and configured so that the light emitting direction from the main wave-combining unit is generally perpendicular to the optical axes of the first and second monitoring waveguides.

6. A light source with a monitoring function comprising:
the light combining circuit according to claim 2 ;
three laser diodes for outputting the first wavelength light, the second wavelength light, and the third wavelength light, respectively; and
a photo diode optically coupled to the first and second monitoring waveguides.

7. A light source with a monitoring function comprising:
the light combining circuit according to claim 1 ;
three laser diodes for outputting the first wavelength light, the second wavelength light, and the third wavelength light, respectively; and
a photo diode optically coupled to the first and second monitoring waveguides.

8. The light source with a monitoring function according to claim 7 , wherein
the three laser diodes output the three primary colors light of R(red light), G(green light), and B(blue light), respectively.

9. The light combining circuit according to claim 1 , wherein
the output waveguide has a termination at a position shifted from the extension in the guided wave direction from the output point of the main wave-combining unit.

10. A light source with a monitoring function comprising:
the light combining circuit according to claim 5 ;
three laser diodes for outputting the first wavelength light, the second wavelength light, and the third wavelength light, respectively; and
a photo diode optically coupled to the first and second monitoring waveguides.

11. The light combining circuit according to claim 1 , further comprising:
a monitoring wave-combining unit disposed in the middle of the first monitoring waveguide, the monitoring wave-combining unit having the same configuration as the main wave-combining unit.

12. A light source with a monitoring function comprising:
the light combining circuit according to claim 11 ;
three laser diodes for outputting the first wavelength light, the second wavelength light, and the third wavelength light, respectively; and
a photo diode optically coupled to the first and second monitoring waveguides.

13. The light combining circuit according to claim 11 , wherein
the output waveguide has a termination at a position shifted from the extension in the guided wave direction from the output point of the main wave-combining unit.

14. The light combining circuit according to claim 11 , wherein
the first and second monitoring waveguides are bent waveguides for optical path conversion and configured so that the light emitting direction from the main wave-combining unit is generally perpendicular to the optical axes of the first and second monitoring waveguides.

15. The light combining circuit according to claim 11 , wherein at least one of the preliminary wave-combining unit or the monitoring wave-combining unit has an output guided-wave direction inclined to an output guided-wave direction of the main wave-combining unit.

16. The light combining circuit according to claim 15 , wherein
the output waveguide has a termination at a position shifted from the extension in the guided wave direction from the output point of the main wave-combining unit.

17. The light combining circuit according to claim 15 , wherein
the first and second monitoring waveguides are bent waveguides for optical path conversion and configured so that the light emitting direction from the main wave-combining unit is generally perpendicular to the optical axes of the first and second monitoring waveguides.

18. A light source with a monitoring function comprising:
the light combining circuit according to claim 15 ;
three laser diodes for outputting the first wavelength light, the second wavelength light, and the third wavelength light, respectively; and
a photo diode optically coupled to the first and second monitoring waveguides.

19. The light combining circuit according to claim 1 , wherein the first and second monitoring waveguides are bent waveguides for optical path conversion and configured so that the light emitting direction from the main wave-combining unit is generally perpendicular to the optical axes of the first and second monitoring waveguides.

20. A light source with a monitoring function comprising:
the light combining circuit according to claim 19 ;
three laser diodes for outputting the first wavelength light, the second wavelength light, and the third wavelength light, respectively; and
a photo diode optically coupled to the first and second monitoring waveguides.

Assignees

• Nippon Telegraph & Telephone

Inventors

• Sakamoto Junji
• Nemoto Naru
• Hashimoto Toshikazu

Classifications

• G02B6/4286 Primary

  Optical modules with optical power monitoring · CPC title

• G02B6/4215

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

• G02B6/12007 Primary

  forming wavelength selective elements, e.g. multiplexer, demultiplexer · CPC title

• G02B6/12004

  Combinations of two or more optical elements · CPC title