Sagnac interferometric switch utilizing faraday rotation
AssigneeIowa State University Research Foundation, Inc.
InventorsSasha N. Kemmet, Jin-Wei Tioh, Mani Mina, Robert J. Weber
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Abstract
A fiber-based, magneto-optic (MO) optical modulator or switch based on Sagnac interferometry is provided. The system uses a magneto-optic Faraday rotator (MOFR) to produce optical modulation with low magnetic fields. The Sagnac geometry allows for increased modulation at lower fields than traditional MO modulators. This switch uses the MOFR to create different states of polarization in counter-propagating waves, which results in interference at the output port. A magnetic field is used to control the amount of rotation in the state of polarization (SOP), and therefore, the ON-OFF extinction ratio.
Claims21
An optical switch, comprising:
- a Sagnac interferometer having an input port and an output port coupled to a Sagnac loop through an optical coupler configured to split an incoming optical signal into two counter-propagating waves around the Sagnac loop;
- a magneto-optic Faraday rotator (MOFR) interposed in the Sagnac loop, wherein the MOFR is a bismuth substituted iron garnet Faraday rotator;
- a magnetic circuit associated with the MOFR;
- and
- wherein modulation of the magnetic circuit via current flow that is switched in approximately 100 ns operates to turn the optical switch on and off.
An optical switch, comprising:
- a Sagnac interferometer having an input port and an output port coupled to a Sagnac loop through an optical coupler configured to split an incoming optical signal into two counter-propagating waves around the Sagnac loop;
- a magneto-optic Faraday rotator (MOFR) interposed in the Sagnac loop;
- a magnetic circuit associated with the MOFR;
- and
- wherein modulation of the magnetic circuit operates to turn the optical switch on and off;
- wherein the magnetic circuit comprises a coil in magnetic communication with the MOFR;
- and
- wherein the magnetic circuit further comprises a modulation circuit operably coupled to the coil to supply current thereto so as to control generation of a magnetic field produced by the coil;
- and
- wherein the modulation circuit comprises a pulse generator driving a switching transistor that provides a path for current flow through the coil.
An optical switch, comprising:
- a Sagnac interferometer having an input port and an output port coupled to a Sagnac loop through an optical coupler configured to split an incoming optical signal into two counter-propagating waves around the Sagnac loop;
- a magneto-optic Faraday rotator (MOFR) interposed in the Sagnac loop;
- a magnetic circuit associated with the MOFR;
- and
- wherein modulation of the magnetic circuit operates to turn the optical switch on and off;
- wherein the magnetic circuit comprises a coil in magnetic communication with the MOFR;
- and
- wherein the magnetic circuit further comprises a modulation circuit operably coupled to the coil to supply current thereto so as to control generation of a magnetic field produced by the coil;
- and
- wherein the modulation circuit operates to switch current flow through the coil in approximately 100 ns.
Dependencies are inferred from the claim text.