Optical functional device, optical receiving apparatus and optical transmission apparatus

Patent metadata

Field	Value
Publication number	US-9874709-B2
Application number	US-201514955600-A
Country	US
Kind code	B2
Filing date	Dec 1, 2015
Priority date	Dec 3, 2014
Publication date	Jan 23, 2018
Grant date	Jan 23, 2018

Abstract

An optical functional device includes: a photodetector; a first optical waveguide which is connected to one end face of the photodetector; and a second optical waveguide which is connected to the other end face of the photodetector. The photodetector is formed in a multi-mode interferometer and has electrodes. Light input from the first optical waveguide to the photodetector focuses image at a position physically away from the second optical waveguide, and light input from the second optical waveguide to the photodetector focuses image at a position physically away from the first optical waveguide.

First claim

What is claimed is:

1. An optical functional device, comprising:
a photodetector which is formed in a multi-mode interferometer and has electrodes;
a first optical waveguide which is connected to one end face of the photodetector; and
a second optical waveguide which is connected to the other end face of the photodetector,
wherein light input from the first optical waveguide or the second optical waveguide, or from the first optical waveguide and the second optical waveguide to the photodetector is separated into lights in a plurality of propagation modes, the separated lights propagate in the photodetector while interfering, and a photocurrent generated by photoelectrically converting the lights is detected from the electrodes,
the light input from the first optical waveguide to the photodetector focuses image at a position physically away from the second optical waveguide, and
the light input from the second optical waveguide to the photodetector focuses image at a position physically away from the first optical waveguide.

2. The optical functional device according to claim 1 ,
wherein the light input from the first optical waveguide to the photodetector focuses image at right and left two positions of the second optical waveguide at the other end face of the photodetector, and
the light input from the second optical waveguide to the photodetector focuses image at right and left two positions of the first optical waveguide at the one end face of the photodetector.

3. The optical functional device according to claim 2 , further comprising:
a third optical waveguide and a fourth optical waveguide in which one ends are respectively connected to right and left two positions of the second optical waveguide at the other end face; and
a fifth optical waveguide and a sixth optical waveguide in which one ends are respectively connected to right and left two positions of the first optical waveguide at the one end face,
wherein the light input from the first optical waveguide to the photodetector focuses image at the third optical waveguide and the fourth optical waveguide, and
the light input from the second optical waveguide to the photodetector focuses image at the fifth optical waveguide and the sixth optical waveguide.

4. The optical functional device according to claim 3 ,
wherein optical absorbers are connected respectively to the other end of the third optical waveguide, the other end of the fourth optical waveguide, the other end of the fifth optical waveguide, and the other end of the sixth optical waveguide.

5. An optical receiving apparatus, comprising:
an optical separation part which separates input light into TE polarization light and TM polarization light;
an optical rotation part which rotates the TM polarization light into the TE polarization light;
an optical demultiplexing part which demultiplexes the TE polarization light in accordance with a wavelength; and
an optical functional device which receives the demultiplexed TE polarization light,
wherein the optical functional device includes:
a photodetector which is formed in a multi-mode interferometer and has electrodes;
a first optical waveguide which is connected to one end face of the photodetector; and
a second optical waveguide which is connected to the other end face of the photodetector,
wherein light input from the first optical waveguide or the second optical waveguide, or from the first optical waveguide and the second optical waveguide to the photodetector is separated into lights in a plurality of propagation modes, the separated lights propagate in the photodetector while interfering, and a photocurrent generated by photoelectrically converting the lights is detected from the electrodes,
the TE polarization light input from the first optical waveguide to the photodetector focuses image at a position physically away from the second optical waveguide, and
the TE polarization light input from the second optical waveguide to the photodetector focuses image at a position physically away from the first optical waveguide.

6. The optical receiving apparatus according to claim 5 ,
wherein in the optical functional device,
the light input from the first optical waveguide to the photodetector focuses image at right and left two positions of the second optical waveguide at the other end face of the photodetector, and
the light input from the second optical waveguide to the photodetector focuses image at right and left two positions of the first optical waveguide at the one end face of the photodetector.

7. The optical receiving apparatus according to claim 6 ,
wherein the optical functional device further includes:
a third optical waveguide and a fourth optical waveguide in which one ends are respectively connected to right and left two positions of the second optical waveguide at the other end face; and
a fifth optical waveguide and a sixth optical waveguide in which one ends are respectively connected to right and left two positions of the first optical waveguide at the one end face,
wherein the light input from the first optical waveguide to the photodetector focuses image at the third optical waveguide and the fourth optical waveguide, and
the light input from the second optical waveguide to the photodetector focuses image at the fifth optical waveguide and the sixth optical waveguide.

8. The optical receiving apparatus according to claim 7 ,
wherein in the optical functional device,
optical absorbers are connected respectively to the other end of the third optical waveguide, the other end of the fourth optical waveguide, the other end of the fifth optical waveguide, and the other end of the sixth optical waveguide.

9. An optical transmission apparatus, comprising:
a light source;
an optical waveguide in which one end is an input part of light emitted from the light source and the other end is an output part of signal light;
an optical modulator which is connected to the optical waveguide; and
an optical functional device which is connected to the optical modulator,
wherein the optical functional device includes:
a photodetector which is formed in a multi-mode interferometer and has electrodes;
a first optical waveguide which is connected to one end face of the photodetector; and
a second optical waveguide which is connected to the other end face of the photodetector,
wherein light input from the first optical waveguide or the second optical waveguide, or from the first optical waveguide and the second optical waveguide to the photodetector is separated into lights in a plurality of propagation modes, the separated lights propagate in the photodetector while interfering, and a photocurrent generated by photoelectrically converting the lights is detected from the electrodes,
the light input from the first optical waveguide to the photodetector focuses image at a position physically away from the second optical waveguide, and
the light input from the second optical waveguide to the photodetector focuses image at a position physically away from the first optical waveguide.

10. The optical transmission apparatus according to claim 9 ,
wherein in the optical functional device,
the light input from the first optical waveguide to the photodetector focuses image at right and left two positions of the second optical waveguide at the other end face of the photodetector, and
the light input from the second optical waveguide to the photodetector focuses image at right and left two positions of the first optical waveguide at the one end face of the photodetector.

11. The optical transmission apparatus according to claim 10 ,
wherein the optical functional device further in

Assignees

• Fujitsu Ltd
• Photonics Electronics Technology Res Ass

Inventors

• Hayakawa Akinori

Classifications

• G02B2006/12142

  Modulator · CPC title

• G02B2006/12138

  Sensor · CPC title

• G02B6/4295 Primary

  coupling with semiconductor devices activated by light through the light guide, e.g. thyristors, phototransistors · CPC title

• G02B6/2934

  Fibre ring resonators, e.g. fibre coils · CPC title

• G02B6/29382

  including at least adding or dropping a signal, i.e. passing the majority of signals · CPC title