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US 8,014,067 B2Granted
High extinction ratio and low crosstalk compact optical switches
AssigneeOclaro (North America), Inc.
InventorsMing Li, Song Peng
Life of this patent
Estimating the term…
Abstract
An improved optical switch utilizes one polarization modulator, with the beam components traversing it twice. Because of the twice traverse, the extinction ratio of the switch is doubled without the addition of another polarization modulator, thus avoiding the costs of additional optical components. With no additional components, the switch is more compact than conventional switches with the same extinction ratio. Fewer components also result in more thermal and long-term stability and less crosstalk.
Claims16
An optical switch, comprising:
- a first birefringent polarization beam displacer configured to separate an input optical beam into a first beam component having a first polarization and a second beam component having a second polarization, wherein the first polarization is orthogonal to the second polarization;
- a polarization modulator operable in at least first and second states configured to rotate the polarization of beams by 0 or 90 degrees, wherein the polarization modulator is positioned in optical paths of the first beam component and the second beam component, wherein the polarization of the first beam component is rotated by 0 degrees when the first beam component passes through the polarization modulator while the polarization modulator is in the first state and by 90 degrees when the first beam component passes through the polarization modulator while the polarization modulator is in the second state, and the polarization of the second beam component is rotated by 90 degrees when the second beam component passes through the polarization modulator while the polarization modulator is in the first state and by 0 degrees when the second beam component passes through the polarization modulator while the polarization modulator is in the second state;
- a second birefringent polarization beam displacer optically coupled to the polarization modulator at a side opposite to the first birefringent polarization beam displacer;
- and
- a reflector positioned to reflect beams output from the second birefringent polarization beam displacer so that the reflected beams pass through the second birefringent polarization beam displacer, the polarization modulator, and the first birefringent polarization beam displacer,
- wherein the first birefringent polarization beam displacer is configured to combine the reflected beams into an output signal which is sent to a first output port when the polarization modulator is in the first state and to a second output port when the polarization modulator is in the second state.
3 more elements
A method for switching an optical signal received through an input port between a first output port and a second output port, comprising:
- passing an input optical signal through a first birefringent polarization beam displacer and separating the input optical signal into a first beam component with a first polarization and a second beam component with a second polarization;
- passing the first and second beam components through a polarization modulator while the polarization modulator is in a first state, wherein the polarization of the first beam component is rotated by 0 degrees when the first beam component passes through the polarization modulator and the polarization of the second beam component is rotated by 90 degrees when the second beam component passes through the polarization modulator;
- passing the first and second beam components output from the polarization modulator through a second birefringent polarization beam displacer;
- reflecting beams output from the second birefringent polarization beam displacer;
- passing the reflected beams through the second birefringent polarization beam displacer, the polarization modulator that is in the first state, and the first birefringent polarization beam displacer to produce an output signal at one of the first and second output ports;
- and
- controlling the polarization modulator to be in a second state to produce an output signal at the other one of the first and second output ports.
4 more elements
An optical switch, comprising:
- a first birefringent polarization beam displacer configured to separate an input optical beam into a first beam component having a first polarization and a second beam component having a second polarization, wherein the first polarization is orthogonal to the second polarization;
- a polarization modulator having a single pixel that is positioned in optical paths of the first beam component and the second beam component to rotate the polarization of incident beam components by 90 degrees each time the incident beam components pass through the single pixel;
- a half-wave plate positioned between the first birefringent polarization beam displacer and the polarization modulator and in the optical path of the first beam component but not in the optical path of the second beam component;
- a second birefringent polarization beam displacer optically coupled to the polarization modulator at a side opposite to the first birefringent polarization beam displacer;
- and
- a reflector positioned to reflect beams output from the second birefringent polarization beam displacer so that the reflected beams pass through the second birefringent polarization beam displacer, the single pixel of the polarization modulator, and the first birefringent polarization beam displacer to produce an output signal at one of first and second output ports.
3 more elements
An optical switch, comprising:
- a first birefringent polarization beam displacer configured to separate an input optical beam into a first beam and a second beam;
- a polarization modulator operable in at least first and second states configured to rotate the polarization of the first and second beams by 0 or 90 degrees when the first and second beams are transmitted therethrough;
- a second birefringent polarization beam displacer optically coupled to the polarization modulator at a side opposite to the first birefringent polarization beam displacer and positioned to receive the first and second beams passing through the polarization modulator;
- and
- a reflector positioned to reflect the first and second beams output from the second birefringent polarization beam displacer so that the reflected beams pass through the second birefringent polarization beam displacer and the polarization modulator, and are combined by the first birefringent polarization beam displacer into a single output beam which is sent to a first output port when the polarization modulator is in the first state and to a second output port when the polarization modulator is in the second state.
2 more elements
Dependencies are inferred from the claim text.