DEMULTIPLEXER AND OPTICAL DEMULTIPLEXING METHOD

• US 20130161496A1
• Filed: 09/13/2012
• Published: 06/27/2013
• Est. Priority Date: 12/21/2011
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Akiyama, Tomoyuki
• Granted Patent: US 9,184,865 B2
• Time in Patent Office: Days
• US Class Current: 250/227.23
• CPC Class Codes: G02B 6/12007 forming wavelength selective elements, e.g. multiplexer, demultiplexer
• CPC Class Codes: G02F 1/0147 based on thermo-optic effects G02F1/132 takes precedence
• CPC Class Codes: G02F 1/311 Cascade arrangement of plural switches
• CPC Class Codes: G02F 1/313 in an optical waveguide structure
• CPC Class Codes: G02F 1/3132 of directional coupler type
• CPC Class Codes: G02F 2201/06 integrated waveguide
• CPC Class Codes: G02F 2201/58 Arrangements comprising a monitoring photodetector
• CPC Class Codes: G02F 2202/101 Ga×As and alloy
• CPC Class Codes: G02F 2202/105 single crystal Si
• CPC Class Codes: G02F 2203/05 wavelength dependent
• CPC Class Codes: G02F 2203/15 involving resonance effects, e.g. resonantly enhanced interaction
• CPC Class Codes: G02F 2203/58 Multi-wavelength, e.g. operation of the device at a plurality of wavelengths
• CPC Class Codes: G02F 2203/585 Add/drop devices
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems
• CPC Class Codes: H04J 14/0212 using optical switches or wavelength selective switches [WSS]

Abstract

An optical switch includes a substrate, a ring resonator formed on the substrate, a first waveguide formed on the substrate in optical coupling with the ring resonator, the first waveguide being configured to guide a WDM signal, an optical detector configured to detect an optical signal component in said ring resonator, a temperature regulator driven in response to an output signal of the optical detector, the temperature regulator being configured to change a temperature of the ring resonator, the ring resonator having a resonant wavelength corresponding to a wavelength of an optical signal component that constitutes the WDM signal, the ring resonator, the optical detector and the temperature regulator constituting together a feedback control system that locks the resonant wavelength of the ring resonator to the wavelength of the optical signal component in the WDM signal.

Claims

1. An optical switch, comprising:

a substrate;

a ring resonator formed on said substrate;

a first waveguide formed on said substrate in optical coupling with said ring resonator, said first waveguide being configured to guide a WDM signal;

an optical detector configured to detect an optical signal component in said ring resonator;

a temperature regulator driven in response to an output signal of said optical detector, said temperature regulator being configured to change a temperature of said ring resonator,

said ring resonator having a resonant wavelength corresponding to a wavelength of an optical signal component that constitutes said WDM signal,

said ring resonator, said optical detector and said temperature regulator constituting together a feedback control system that locks said resonant wavelength of said ring resonator to said wavelength of said optical signal component in said WDM signal.

2. The optical switch as claimed in claim 1, wherein said temperature regulator includes a heater configured to heat said ring resonator, a driving power source configured to drive said heater and a starter switch configured to select, upon operation, one of said optical detector and said driving source as a selected device, said starter switch is further configured to supply an output of said selected device to said heater.

3. The optical switch as claimed in claim 1, further including a signal processing unit configured to process said output signal of said optical detector, said signal processing unit including a current-to-voltage conversion device configured to convert said output signal of said optical detector from a current signal to a voltage signal, and wherein said temperature regulator is driven by said voltage signal converted by said current-to-voltage conversion device.

4. The optical switch as claimed in claim 1, wherein said temperature regulator includes a low-pass filter configured to eliminate a high-frequency component from said output signal of said optical detector, said temperature regulator being configured to be driven in response to said output signal of said optical detector from which said high-frequency component is eliminated and is further configured to cause a temperature change in said ring resonator.

5. The optical switch as claimed in claim 1, wherein said temperature regulator includes an amplifier configured to amplify said output signal of said optical detector, said temperature regulator being configured to be driven in response to said amplified output signal of said optical detector and is further configured to cause a temperature change in said ring resonator.

6. The optical switch as claimed in claim 5, wherein said amplifier amplifies said output signal of said optical detector such that a temperature of said ring resonator increases above a temperature in which said resonant wavelength of said ring resonator and said wavelength of said optical signal component are coincident.

7. The optical switch as claimed in claim 5, wherein said amplifier comprises a linear amplifier.

8. The optical switch as claimed in claim 5, wherein said amplifier comprises a non-linear amplifier.

9. The optical switch as claimed in claim 3, wherein said signal processing unit includes a comparator configured to perform a threshold processing to said output signal of said optical detector, and wherein said temperature regulator is driven in response to an output signal of said comparator.

10. The optical switch as claimed in claim 1, further including a second waveguide provided on said substrate in optical coupling with said ring resonator, said second waveguide being confirmed to guide a signal component of said WDM signal, said optical detector being optically coupled to said second waveguide.

11. The optical switch as claimed in claim 10, wherein said optical resonator is formed on a first region of said substrate defined by a trench, said optical detector being formed in a second region outside said first region, said second waveguide extending from said first region to said second region at an area wherein said trench is interrupted.

12. The optical switch as claimed in claim 1, wherein said optical detector is formed in said ring resonator as a part of said ring resonator.

13. An optical demodulator, comprising:

a substrate,

a waveguide formed on said substrate, said waveguide being configured be supplied with a WDM signal at an end and guiding said WDM signal to the other end;

a plurality of optical switches formed on said substrate consecutively along said waveguide, each of said plurality of optical switches including a ring resonator coupled optically to said optical waveguide and having a resonant wavelength corresponding to an optical signal component in said WDM signal;

an optical detector configured to detect an optical signal component in said ring resonator;

a signal processing unit configured to process an output signal of said optical detector to produce an electric signal corresponding to said optical signal component;

a temperature regulator driven in response to an output signal of said optical detector, said temperature regulator being configured to change a temperature of said ring resonator,

said ring resonator, said optical detector and said temperature regulator constituting together a feedback control system that locks said resonant wavelength of said ring resonator to said wavelength of said optical signal component in said WDM signal.

14. The optical demodulator as claimed in claim 13, wherein said temperature regulator includes a heater configured to heat said ring resonator, a driving power source configured to drive said heater and a starter switch configured to select, upon operation, one of said optical detector and said driving source as a selected device, said starter switch is further configured to supply an output of said selected device to said heater.

15. An optical demodulation method using an optical demodulator of claim 14, said demodulation method comprising:

a first step of selecting said drive power source by said starter switch and heating said ring resonator by said heater to a temperature at which a resonant wavelength of said ring resonator is longer than a wavelength of said optical signal component,

a second step of supplying a WDM signal to said optical waveguide, and

a third step, after said first step and said second step, of selecting an output signal of said optical detector by said starter switch and locking said wavelength of said ring resonator to said wavelength of said optical signal component.