US 6,643,424 B2Granted

Silicon oxynitride optical waveguide switch with wavelength locked feedback control

AssigneeInternational Business Machines Corporation

InventorsLawrence Jacobowitz, Casimer M. DeCusatis

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Abstract

A silicon oxynitride (SiON)/silicon dioxide (SiO2) optical waveguide switch with a wavelength locked feedback control loop which monitors the wavelength of UV radiation produced by a UV tunable laser diffraction grating write source which has passed through a UV bandpass filter and is then used to selectively write a diffraction grating in the optical waveguide switch. The diffraction grating structure can be switched on or off at will, resulting in an optical switch element for IR radiation traveling through the optical waveguide. This optical switch element is a basic building block which can be used for many other systems, such as optical logic gates or all-optical cross connect switches for wide area networks. Further, it may be used to selectively tap off a portion of the optical signal, for example to read header information in a data stream (or packets) which indicates the destination switch port of the optical data, without disrupting the remaining optical data.

Claims17

Dependent claims

A silicon oxynitride (SiON)/silicon dioxide (SiO2) optical waveguide switch comprising:

a SiON/SiO2 optical waveguide structure;
a UV wavelength tunable diffraction grating write source for generating a UV write beam for writing a diffraction grating pattern in the optical waveguide;
a dither source producing a dither signal for modulating the wavelength of the UV tunable write source;
a UV bandpass filter, receiving the UV write beam, and passing a center wavelength which will write the diffraction pattern in the optical waveguide;
a dither-operated, wavelength-locked feedback loop, sampling the output of the UV bandpass filter and generating a feedback control signal for controlling the wavelength of the UV write source to write the diffraction grating pattern in the optical waveguide, or not
a logic circuit for controlling the TV write source, wherein:
to write the diffraction pattern, and if the feedback control signal indicates that the center wavelengths of the UV write source and the UV filter are aligned, then the logic circuit output is zero card no change is made to the center wavelength of the UV write source, and if the center wavelength of the UV write source and the UV filter are not aligned, the feedback control signal is used to determine in which direction and by what amount the drive signal of the UV write source is changed to bring them into alignment, and the feedback control signal is fed back to the UV write source
to not write the diffraction pattern and if the feedback control signal indicates that the center wavelengths of the UV write source and the UV filter are not aligned, the logic output is zero and no change is made to the center wavelength of the UV write source, and if the feedback control signal indicates that the center wavelengths of the UV write source and the UV filter are aligned, then the feedback signal determines in which direction and by what amount the drive signal of the UV write source is changed to bring them out of alignment.

5 more elements

A method of operating a silicon oxynitride (SiON)/silicon dioxide (SiO2) optical waveguide switch comprising:

generating a UV write beam with a UV wavelength tunable diffraction grating write source for writing a diffraction grating pattern in a SiON/SiO2 optical waveguide;
producing a dither signal for modulating the wavelength of the UV tunable write source;
receiving the UV write beam with a UV bandpass filter, and passing a center wavelength which will write the diffraction pattern in the optical waveguide;
sampling the output of the UV bandpass filter and generating a feedback control signal, a dither-operated, wavelength-locked loop, for controlling the wavelength of the UV write source to write the diffraction grating patter in the optical waveguide, or not;
adjusting the state of the feedback control signal, wherein:
to write the diffraction pattern, and if the feedback control signal indicates that the center wavelengths of the UV write source and the UV filter are aligned, then the logic circuit output is zero and no change is made to the center wavelength of the UV write source, and if the center wavelength of the UV write source and the UV filter are not aligned, the feedback control signal is used to determine in which direction and by what amount the drive signal of the UV write source is changed to bring them into alignment, and the feedback control signal is fed back to the UV write source;
to not write the diffraction pattern and if the feedback control signal indicates that the center wavelengths of the UV write source and the UV filter are not aligned, the logic output is zero and no change is made to the center wavelength of the UV write source, and if the feedback control signal indicates that the center wavelengths of the UV write source and the UV filter are aligned, then the feedback signal determines in which direction and by what amount the drive signal of the UV write source is changed to bring them out of alignment.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/944,274Filed 31 Aug 2001
Published: US 2003/0169959 A111 Sep 2003
Granted: 4 Nov 2003
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

G02F 1/011
For the control of the intensity, phase, polarisation or colour: in optical waveguides, not otherwise provided for in this subclass
G02B 6/124
Basic optical elements, e.g. light-guiding paths: geodesic lenses or integrated gratings
G02B 2006/12145
Functions: switch
G02F 1/0126
For the control of the intensity, phase, polarisation or colour: opto-optical modulation, i.e. control of one light beam by another light beam,…