Optical waveguide device having a light absorber for split out modes

Patent metadata

Field	Value
Publication number	US-9857534-B2
Application number	US-201314422926-A
Country	US
Kind code	B2
Filing date	Aug 13, 2013
Priority date	Aug 22, 2012
Publication date	Jan 2, 2018
Grant date	Jan 2, 2018

Abstract

An optical waveguide device includes: a mode splitter including a main waveguide in which lights can be propagated in at least two propagation modes with different propagation orders and a subsidiary waveguide which includes a coupling section disposed in parallel with the main waveguide at a certain distance away from the main waveguide so as to constitute a directional coupler and is capable of splitting at least one propagation mode out of the two or more propagation modes from the main waveguide. Also, n core /n cladding which is a refractive index ratio between a core and a cladding which constitute the main waveguide and the subsidiary waveguide is in a range of 101% to 250%.

First claim

The invention claimed is:

1. An optical waveguide device comprising:
an optical coupler section which couples two input beams into one output beam; and
a mode splitter which includes a main waveguide in which beams are configured to be propagated in at least two propagation modes with different propagation orders and a subsidiary waveguide which includes a coupling section disposed in parallel with the main waveguide at a certain distance away from the main waveguide so as to constitute a directional coupler and is configured to split at least one propagation mode out of the two or more propagation modes from the main waveguide, the mode splitter being provided in a front section which is on an input side of the optical coupler section, wherein
n core /n cladding which is a refractive index ratio between a core and a cladding which constitute the main waveguide and the subsidiary waveguide is in a range of 101% to 250%,
the mode splitter is provided in both of two waveguides in the front section of the optical coupler section,
a phase modulator is provided in a front section of one of the mode splitters,
a waveguide, which is connected to the input side of the optical coupler section from the main waveguide, is a multi-mode waveguide which guides a beam in a multi-mode, the subsidiary waveguide is configured to split high-order modes from the main waveguide, and
wherein a light-absorbing layer doped with impurities is provided in a termination section of the subsidiary waveguide.

2. The optical waveguide device according to claim 1 , wherein
another mode splitter is further provided in a rear section which is on an output side of the optical coupler section.

3. The optical waveguide device according to claim 1 , wherein
two input-side waveguides and an output-side waveguide, which are connected to the optical coupler section, are multi-mode waveguides which guide a beam in a multi-mode.

4. The optical waveguide device according to claim 1 , further comprising:
a Mach-Zehnder optical modulator constituted of an optical splitter section which splits one input beam into two split beams and the optical coupler section, wherein
in the Mach-Zehnder optical modulator, the mode splitter is disposed in at least one of the rear section of the optical coupler section and inside the Mach-Zehnder optical modulator which is between the optical splitter section and the optical coupler section.

5. The optical waveguide device according to claim 1 , further comprising:
an optical splitter section which splits one input beam into two split beams and is provided in a front section which is on an input side of the optical coupler section, wherein
first output beam from the optical splitter section is input to the optical coupler section through a waveguide having the phase modulator, and second output beam from the optical splitter section is input to the optical coupler section through a waveguide having no phase modulator.

6. The optical waveguide device according to claim 1 , wherein the coupler section is an MMI-type optical coupler.

7. The optical waveguide device according to claim 1 , wherein the coupler section is a Y-type coupler/splitter.

8. The optical waveguide device according to claim 1 , further comprising:
a photo detector and an electric wire for ejecting a current from the photo detector which are disposed at a front end of the termination section of the subsidiary waveguide.

9. The optical waveguide device according to claim 1 , wherein the subsidiary waveguide further comprises an initiation section, extending from an input end of the subsidiary waveguide to the coupling section of the subsidiary waveguide, a termination section, extending from the coupling section of the subsidiary waveguide to an output end of the subsidiary waveguide, wherein the initiation section is substantially symmetrical to the termination section with respect to the coupling section, and the initiation section smoothly curves toward the main waveguide as the initiation section curves from the input end of the subsidiary waveguide toward the coupling section of the subsidiary waveguide.

10. An optical waveguide device comprising:
an optical coupler section which couples two input beams into one output beam; and
a mode splitter which includes a main waveguide in which beams are configured to be propagated in at least two propagation modes with different propagation orders and a subsidiary waveguide which includes a coupling section disposed in parallel with the main waveguide at a certain distance away from the main waveguide so as to constitute a directional coupler and is configured to split at least one propagation mode out of the two or more propagation modes from the main waveguide, the mode splitter being provided in a rear section which is on an output side of the optical coupler section; and
a phase modulator which is provided in a front section which is on an input side of the optical coupler section, wherein
n core /n cladding which is a refractive index ratio between a core and a cladding which constitute the main waveguide and the subsidiary waveguide is in a range of 101% to 250%,
in a case in which two input beams are in phase, a coupled beam of the two input beams propagates through an optical waveguide in a rear section of the coupling section in a basic mode, and the optical signal changes into an ON state,
in a case in which two input beams are in opposite phase, the coupled beam propagates through the optical waveguide in the rear section of the rear section of the coupling section in a first-order mode, and the optical signal changes into an OFF state,
a waveguide of the main waveguide, which is connected to the main waveguide from the output side of the optical coupler section, is a multi-mode waveguide which guides a beam in a multi-mode, the subsidiary waveguide is configured to split the first-order mode from the main waveguide, and the mode splitter includes a photo detector which monitors a light intensity of a beam in the first-order mode branched into the subsidiary waveguide, and
wherein a light-absorbing layer doped with impurities is provided in a termination section of the subsidiary waveguide.

11. The optical waveguide device according to claim 10 , wherein
two input-side waveguides and an output-side waveguide, which are connected to the optical coupler section, are multi-mode waveguides which guide a beam in a multi-mode.

12. The optical waveguide device according to claim 10 , further comprising:
a Mach-Zehnder optical modulator constituted of an optical splitter section which splits one input beam into two split beams and the optical coupler section, wherein
in the Mach-Zehnder optical modulator, the mode splitter is disposed in at least one of the rear section of the optical coupler section and inside the Mach-Zehnder optical modulator which is between the optical splitter section and the optical coupler section.

13. The optical waveguide device according to claim 10 , further comprising:
an optical splitter section which splits one input beam into two split beams and is provided in a front section which is on an input side of the optical coupler section, wherein
a first output beam from the optical splitter section is input to the optical coupler section through a waveguide having the phase modulator, and a second output beam from the optical splitter section is input to the optical coupler section through a waveguide having no phrase modulator.

14. The optical waveguide device according to claim 10 , wherein the optical coupler section is an MMI-type optical coupler.

15

Assignees

• Fujikura Ltd

Inventors

• Kusaka Hiroyuki
• Ogawa Kensuke
• Goi Kazuhiro

Classifications

• G02B6/2813

  based on multimode interference effect, i.e. self-imaging · CPC title

• G02F2001/212

  Physics · mapped topic

• G02F1/225

  in an optical waveguide structure · CPC title

• G02F1/2255 Primary

  controlled by a high-frequency electromagnetic component in an electric waveguide structure · CPC title

• G02B6/125

  Bends, branchings or intersections · CPC title