OPTICALLY FUNCTIONAL DEVICE, AND MANUFACTURING METHOD THEREOF

• US 20150063801A1
• Filed: 03/22/2013
• Published: 03/05/2015
• Est. Priority Date: 03/30/2012
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Ishizaka, Masashige
• Granted Patent: US 9,729,246 B2
• Time in Patent Office: Days
• US Class Current: 398/48
• CPC Class Codes: G02F 1/0121 Operation of devices; Circuit arrangements, not otherwise provided for in this subclass
• CPC Class Codes: G02F 1/212 Mach-Zehnder type
• CPC Class Codes: G02F 1/2257 the optical waveguides being made of semiconducting material
• CPC Class Codes: G02F 2203/055 wavelength filtering
• CPC Class Codes: G02F 2203/15 involving resonance effects, e.g. resonantly enhanced interaction
• CPC Class Codes: H04B 10/25 Arrangements specific to fibre transmission
• CPC Class Codes: H04B 10/548 Phase or frequency modulation
• CPC Class Codes: H04B 10/564 Power control
• CPC Class Codes: H04Q 11/0005 Switch and router aspects
• CPC Class Codes: H04Q 2011/0035 using miscellaneous components, e.g. circulator, polarisation, acousto/thermo optical
• CPC Class Codes: H04Q 2011/0039 Electrical control

Abstract

An optical functional device equivalent to a 2×2 Mach-Zehnder optical switch is produced by forming two 3 dB couplers and input/output waveguides on a substrate. Two optical phase modulation paths are formed on corresponding waveguides between 3 dB couplers. A channel region having an opposite electric polarity is formed between source and drain regions, having the predetermined electric polarity, formed on the substrate. The optical phase modulation path is insulated from the surrounding area and disposed above the channel region. Additionally, a control electrode (i.e. a gate region) subjected to high-density doping is formed above the optical phase modulation path. By applying an electric voltage having the predetermined polarity to the control electrode, the source region, and the drain region, it is possible to generate hot carriers, in proximity to the optical phase modulation path, so as to accumulate charges and change a refractive index, thus setting a desired light-wave input/output path.

Claims

1. An optical phase modulation device comprising:

an optical modulation path with a refractive index being changed depending on charges accumulated therein, which is configured to change a phase of a light-wave being guided;

an insulating part with a lower refractive index than the optical phase modulation path, which is configured to insulate the optical phase modulation path from a surrounding area; and

a voltage applying means which is configured to apply an electric voltage used to accumulate charges in the optical phase modulation path being insulated from the surrounding area via the insulating part.

2. The optical phase modulation device according to claim 1, wherein the voltage applying means causes hot carriers so as to accumulate charges in the optical phase modulation path.

3. The optical phase modulation device according to claim 1, wherein the optical phase modulation path has a flat cross-sectional shape perpendicular to a light-wave waveguide direction, and wherein the voltage applying means includes a gate region positioned oppositely to one face of the optical phase modulation path, a source region positioned proximately to one end of another face of the optical phase modulation path, and a drain region positioned proximately to another end of another face of the optical phase modulation path.

4. The optical phase modulation device according to claim 3, wherein the gate region transmits a part of excitation light, irradiated from the outside, to the optical phase modulation path.

5. The optical phase modulation device according to claim 4, wherein a plurality of through-holes transmitting excitation light, irradiated from the outside, are formed in the gate region.

6. The optical phase modulation device according to claim 4, wherein the gate region is made of a transparent electrode transmitting excitation light irradiated from the outside.

7. The optical phase modulation device according to claim 1, wherein an optical passage transmitting a light-wave is formed in the insulating part in parallel to the optical phase modulation path, and wherein the optical passage is optically connected to the optical phase modulation path.

8. The optical phase modulation device according to claim 1, wherein the optical phase modulation path is made of poly-silicon.

9. The optical phase modulation device according to claim 1, wherein the optical phase modulation path is formed using a plurality of silicon oxide films and a plurality of silicon nitride films, both of which are deposited in multiple layers.

10. A device setting method for switching and setting a phase of a light-wave being guided by the optical phase modulation device according to claim 3, wherein an electric voltage is applied between the gate region, the source region, and the drain region so as to generate hot carriers, thus accumulating charges in the optical phase modulation path.

11. The device setting method according to claim 10, wherein the voltage applying means applies an electric voltage between the source region and the drain region so as to discharge charges accumulated in the optical phase modulation path.

12. A device setting method for switching and setting a phase of a light-wave being guided by the optical phase modulation device according to claim 4, wherein the optical phase modulation path is configured to accumulate charges when an electric voltage is applied between the gate region, the source region, and the drain region while excitation light from the outside is transmitted through the gate region and irradiated to the optical phase modulation path.

13. A device setting method for switching and setting a phase of a light-wave being guided by the optical phase modulation device according to claim 4, wherein excitation light from the outside is transmitted through the gate region and irradiated to the optical phase modulation path, thus discharging accumulated charges.

14. A device setting method for switching and setting a phase of a light-wave being guided by the optical phase modulation device according to claim 4, wherein the optical phase modulation path is configured to discharge accumulated charges when an electric voltage is applied between the gate region and the source region while excitation light from the outside is transmitted through the gate region and irradiated to the optical phase modulation path.

15. An optical function circuit comprising:

an optical input element configured of a 3 dB coupler including a pair of external input terminals and a pair of internal output terminals;

an optical output element configured of a 3 dB coupler including a pair of internal input terminals and a pair of external output terminals; and

a pair of optical phase modulation paths, according to claim 1, which are formed in parallel so as to optically connect the pair of internal output terminals of the optical input element to the pair of internal input terminals of the optical output element.

16. An optical functional circuit comprising:

a first optical waveguide having an external input terminal and an external output terminal;

a second optical waveguide having an external input terminal and an external output terminal;

a ring-type optical waveguide which is formed in a ring shape to guide a light-wave and which optically connects the first optical waveguide and the second optical waveguide in a tangential manner; and

an optical phase modulation path according to claim 1, which is formed in the ring-type optical waveguide.

17. An optical functional circuit comprising:

a first optical waveguide having an external input terminal and an external output terminal;

a second optical waveguide having an external input terminal and an external output terminal; and

an optical phase modulation path according to claim 1, which is formed in each of the first and second optical waveguides and optically connected together.

18. An optical matrix circuit including a plurality of optical functional circuits according to claim 15, each of which includes a pair of external input terminals and a pair of external output terminals, wherein the external output terminal of one optical functional circuit is optically connected to the external input terminal of another optical functional circuit.

19. The optical phase modulation device according to claim 2, wherein an optical passage transmitting a light-wave is formed in the insulating part in parallel to the optical phase modulation path, and wherein the optical passage is optically connected to the optical phase modulation path.

20. The optical phase modulation device according to claim 3, wherein an optical passage transmitting a light-wave is formed in the insulating part in parallel to the optical phase modulation path, and wherein the optical passage is optically connected to the optical phase modulation path.