Scheme for controlling polarization in waveguides

An integrated optical device configured for splitting TE and TM modes of an optical signal, said device comprising (i) first and second optical waveguide arms arranged to define an optical signal splitting region near an input side of said integrated optical device and an optical signal combining region near an output side of said integrated optical device, (ii) a functional region between said optical signal splitting and combining regions, and (iii) a controller coupled functional region, wherein:

• said first optical waveguide arm comprises a first waveguide core passing through a first electrooptic portion of said functional region;
• said second optical waveguide arm comprises a second waveguide core passing through a second electrooptic portion of said functional region;
• a first set of control electrodes are positioned to generate an electric field in said first portion of said functional region;
• a second set of control electrodes are positioned to generate an electric field in said second portion of said functional region;
• said first set of control electrodes, said first waveguide core, and said first portion of said functional region are configured such that, upon application of suitable voltage to said first set of control electrodes, as established by said controller, a TE electromagnetic polarization mode of an optical signal propagating along said first waveguide core encounters an electrooptically induced change in refractive index that is more predominant than an electrooptically induced change in refractive index encountered by a TM electromagnetic polarization mode of said optical signal propagating along said first waveguide core;
• said second set of control electrodes, said second waveguide core, and said second portion of said functional region are configured such that, upon application of suitable voltage to said second set of control electrodes, as established by said controller, a TM electromagnetic polarization mode of an optical signal propagating along said second waveguide core encounters an electrooptically induced change in refractive index that is more predominant than an electrooptically induced change in refractive index encountered by a TE electromagnetic polarization mode of said optical signal propagating along said second waveguide core;
• and
• said controller is programmed to establish said voltages applied to said first and second sets of control electrodes to affect optical coupling at said optical signal combining region of TE and TM polarized portions of said optical signals propagating along said first and second waveguide cores such that one of said first and second waveguide cores following said optical signal combining region includes an enhanced TE signal while the other of said first and second waveguide cores following said optical signal combining region includes an enhanced TM signal.

A method of operating an integrated optical device configured for splitting TE and TM modes of an optical signal, said device comprising (i) first and second optical waveguide arms arranged to define an optical signal splitting region near an input side of said integrated optical device and an optical signal combining region near an output side of said integrated optical device, (ii) a functional region between said optical signal splitting and combining regions, and (iii) a controller coupled to said functional region, wherein said first optical waveguide arm comprises a first waveguide core passing through a first electrooptic portion of said functional region, said second optical waveguide arm comprises a second waveguide core passing through second electrooptic portion of said functional region, a first set of control electrodes are positioned to generate an electric field in said first portion of said functional region, and a second set of control electrodes are positioned to generate an electric field in said second portion of said functional region, said method comprising:

• applying a suitable voltage to said first set of control electrodes, as established by said controller, such that a TE electromagnetic polarization mode of an optical signal propagating along said first waveguide core encounters an electrooptically induced change in refractive index that is more predominant than an electrooptically induced change in refractive index encountered by a TM electromagnetic polarization mode of said optical signal propagating along said first waveguide core;
• applying a suitable voltage to said second set of control electrodes, as established by said controller, such that a TM electromagnetic polarization mode of an optical signal propagating along said second waveguide core encounters an electrooptically induced change in refractive index that is more predominant than an electrooptically induced change in refractive index encountered by a TE electromagnetic polarization mode of said optical signal propagating along said second waveguide core;
• and
• establishing said voltages applied to said first and second sets of control electrodes to affect optical coupling at said optical signal combining region of TE and TM polarized portions of said optical signals propagating along said first and second waveguide cores such that one of said first and second waveguide cores following said optical signal combining region includes an enhanced TE signal while the other of said first and second waveguide cores following said optical signal combining region includes an enhanced TM signal.

An integrated optical device configured for variable optical attenuation of an optical signal including TE and TM modes of polarization, said device comprising (i) first and second optical waveguide arms arranged to define an optical signal splitting region near an input side of said integrated optical device and an optical signal combining region near an output side of said integrated optical device, (ii) a functional region between said optical signal splitting a combining regions, and (iii) a controller coupled to said functional region, wherein:

• said first optical waveguide arm comprises a first waveguide core passing through a first electrooptic portion of said functional region, said first waveguide core being optically non-functional relative to a remaining portion of said functional region;
• said second optical waveguide arm comprises a second waveguide core passing through a second electrooptic portion of said functional region, said second waveguide core being optically non-functional relative to a remaining portion of said functional region;
• a first set of control electrodes are positioned to generate an electric field in said first portion of said functional region;
• a second set of control electrodes are positioned to generate an electric field in said second portion of said functional region;
• said first set of control electrodes, said first waveguide core, and said first portion of said functional region are configured such that, upon application of suitable voltage to said first set of control electrodes, as established by said controller, a TE electromagnetic polarization mode of an optical signal propagating along said first waveguide core encounters an electrooptically induced change in refractive index that is more predominant than an electrooptically induced change in refractive index encountered by a TM electromagnetic polarization mode of said optical signal propagating along said first waveguide core;
• said second set of control electrodes, said second waveguide core, and said second portion of said functional region are configured such that, upon application of suitable voltage to said second set of control electrodes, as established by said controller, a TM electromagnetic polarization mode of an optical signal propagating along said second waveguide core encounters an electrooptically induced change in refractive index that is more predominant than an electrooptically induced change in refractive index encountered by a TE electromagnetic polarization mode of said optical signal propagating along said second waveguide core;
• and
• said controller is programmed to establish said voltages applied to said first and second sets of control electrodes to affect selective attenuation of TE and TM polarized portions of an optical signal coupled to an input port of a selected one of said waveguide cores on said input side of said integrated optical device, such that said TE and TM polarized portions of said optical signal are attenuated to substantially equal extents at an output port of said selected waveguide core on said output side of said integrated optical device.

A method of operating an integrated optical device configured for variable optical attenuation of TE and TM modes of an optical signal, said device comprising (i) first and second optical waveguide arms arranged to define an optical signal splitting region near an input side of said integrated optical device and an optical signal combining region near an output side of said integrated optical device, (ii) a functional region between said optical signal splitting a combining regions, and (iii) a controller coupled to said functional region, wherein said first optical waveguide arm comprises a first waveguide core passing through a first electrooptic portion of said functional region, said first waveguide core is optically non-functional relative to a remaining portion of said functional region, said second optical waveguide arm comprises a second waveguide core passing through a second electrooptic portion of said functional region, said second waveguide core is optically non-functional relative to a remaining portion of said functional region, a first set of control electrodes are positioned to generate an electric field in said first portion of said functional region, and a second set of control electrodes are positioned to generate an electric field in said second portion of said functional region, said method comprising:

• applying a suitable voltage to said first set of control electrodes, as established by said controller, such that a TE electromagnetic polarization mode of an optical signal propagating along said first waveguide core encounters an electrooptically induced change in refractive index that is more predominant than an electrooptically induced change in refractive index encountered by a TM electromagnetic polarization mode of said optical signal propagating along said first waveguide core;
• applying a suitable voltage to said second set of control electrodes, as established by said controller, such that a TM electromagnetic polarization mode of an optical signal propagating along said second waveguide core encounters an electrooptically induced change in refractive index that is more predominant than an electrooptically induced change in refractive index encountered by a TE electromagnetic polarization mode of said optical signal propagating along said second waveguide core;
• and
• establishing said voltages applied to said first and second sets of control electrodes to affect selective attenuation of TE and TM polarized portions of an optical signal coupled to an input port of a selected one of said waveguide cores on said input side of said integrated optical device, such that said TE and TM polarized portions of said optical signal are attenuated to substantially equal extents at an output port of said selected waveguide core on said output side of said integrated optical device.

An integrated optical device configured to control delay in respective TE and TM modes of polarization of an optical signal, said device comprising:

• a polarization splitter configured to direct a TE mode of an input optical signal to a first optical waveguide arm of said device and a TM mode of said input optical signal to a second optical waveguide arm of said device;
• a polarization combiner configured to combine said TE mode of said first optical waveguide arm with said TM mode of said second optical waveguide arm into an output optical signal;
• a functional region between said optical signal splitting and combining regions, wherein said first optical waveguide arm comprises a first waveguide core passing through a first electrooptic portion of said functional region, said first waveguide core is optically non-functional relative to a remaining portion of said functional region, said second optical waveguide arm comprises a second waveguide core passing through a second electrooptic portion of said functional region, said first waveguide core is optically non-functional relative to a remaining portion of said functional region, a first set of control electrodes are positioned to generate an electric field in said first portion of said functional region, and a second set of control electrodes are positioned to generate an electric field in said second portion of said functional region;
• and
• a delay section in a propagation path between said polarization splitter and said polarization combiner, wherein said delay section is configured to affect a relative phase delay between said TE mode of polarization in said first optical waveguide arm and said TM mode of polarization in said second optical waveguide arm and said control electrodes, at least one of said waveguide cores, and at least a portion of said functional region are configured such that, upon application of suitable voltage to said control electrodes, a first electromagnetic polarization mode of an optical signal propagating along one of said waveguide cores encounters an electrooptically induced change in refractive index that is more predominant than an electrooptically induced change in refractive index encountered by an electromagnetic polarization mode perpendicular to said first polarization mode of said optical signal propagating along said waveguide core.

An integrated optical device configured to convert a selected TE or TM mode of polarization of an optical signal, said device comprising:

• a polarization splitter configured to direct a TE mode of an input optical signal to a first optical waveguide arm of said device and a TM mode of said input optical signal to a second optical waveguide arm of said device;
• a polarization rotator positioned in one of said first and second optical waveguide arms to rotate a polarization mode of an optical signal following propagation through said polarization splitter;
• a delay section in a propagation path between said polarization splitter and said polarization combiner, wherein said delay section is configured to affect a relative phase delay between signals in said first and second optical waveguide arms;
• and
• an output coupler configured to combine optical signals of said first and second optical waveguide arms following propagation through said delay section.

A method of converting a selected TE or TM mode of polarization of an optical signal in an integrated optical device, said method comprising:

• splitting TE and TM polarized components of an optical signal with a polarization splitter by directing a TE mode of an input optical signal to a first optical waveguide arm of said device and directing a TM mode of said input optical signal to a second optical waveguide arm of said device;
• rotating a mode of polarization of one of said TE and TM polarized components in one of said first and second optical waveguide arms following of said optical signal through said polarization splitter;
• causing a relative phase delay between optical signals in said first and second optical waveguide arms following said rotation of one of said TE and TM polarized components of said optical signal;
• and
• combining optical signals of said first and second optical waveguide arms following causation of said relative phase delay.

An optical network comprising at least one transmitter, at least one receiver, a network of transmission lines interconnecting said transmitter and said receiver, and at least one integrated optical device, said integrated optical device comprising (i) first and second optical waveguide arms arranged to define an optical signal splitting region near an input side of said integrated optical device and an optical signal combining region near an output side of said integrated optical device and (ii) a functional region between said optical signal splitting and combining regions, wherein:

• said first optical waveguide arm comprises a first waveguide core passing through a first electrooptic portion of said functional region, said first waveguide core being optically non-functional relative to a remaining portion of said functional region;
• said second optical waveguide arm comprises a second waveguide core passing through a second electrooptic portion of said functional region, said second waveguide core being optically non-functional relative to a remaining portion of said functional region;
• a first set of control electrodes are positioned to generate an electric field in said first portion of said functional region;
• a second set of control electrodes are positioned to generate an electric field in said second portion of said functional region;
• said first set of control electrodes, said first waveguide core, and said first portion of said functional region are configured such that a TE electromagnetic polarization mode of an optical signal propagating along said first waveguide core encounters an electrooptically induced change in refractive index that is more predominant than an electrooptically induced change in refractive index encountered by a TM electromagnetic polarization mode of said optical signal propagating along said first waveguide core;
• and
• said second set of control electrodes, said second waveguide core, and said second portion of said functional region are configured such that a TM electromagnetic polarization mode of an optical signal propagating along said second waveguide core encounters an electrooptically induced change in refractive index that is more predominant than an electrooptically induced change in refractive index encountered by a TE electromagnetic polarization mode of said optical signal propagating along said second waveguide core.

An optical network comprising at least one transmitter, at least one receiver, a network of transmission lines interconnecting said transmitter an said receiver, at least one optical component, a polarization dependent phase shifter, and a phase shift controller, wherein:

• said optical component is configured to introduce a polarization dependent phase delay in an optical signal propagating through said optical network;
• said polarization dependent phase shifter comprises a non-electrooptic waveguide core passing through an electrooptic portion of a functional region of said phase shifter and a set of control electrodes positioned to generate an electric field in said electrooptic portion of said functional region are configured such that a TE electromagnetic polarization mode of an optical signal propagating along said waveguide core encounters an electrooptically induced change in refractive index that is more or less predominant than an electrooptically induced change in refractive index encountered by a TM electromagnetic polarization mode of said optical signal propagating along said waveguide core;
• and
• said controller is programmed to compensate for said polarization dependent phase delay introduced by said optical component by inducing a suitable change in said refractive indices encountered by said TE and TM polarization modes of said optical signal.

An integrated optical device comprising (i) first and second optical waveguide arms arranged to define an optical signal splitting region near an input side of said integrated optical device and an optical signal combining region near an output side of said integrated optical device and (ii) a functional region between said optical signal splitting and combining regions, wherein:

• said first optical waveguide arm comprises a first waveguide core passing through a first portion of said functional region, said first waveguide core being optically non-functional relative to a remaining portion of said functional region;
• said second optical waveguide arm comprises a second waveguide core passing through a second portion of said functional region, said second waveguide core being optically non-functional relative to a remaining portion of said functional region;
• said first waveguide core and said first portion of said functional region are configured such that a TE electromagnetic polarization mode of an optical signal propagating along said first waveguide core encounters an change in refractive index that is more predominant than a change in refractive index encountered by a TM electromagnetic polarization mode of said optical signal propagating along said first waveguide core;
• and
• said second waveguide core and said second portion of said functional region are configured such that a TM electromagnetic polarization mode of an optical signal propagating along said second waveguide core encounters a change in refractive index that is more predominant than a change in refractive index encountered by a TE electromagnetic polarization mode of said optical signal propagating along said second waveguide core.