High-speed electro-optic modulator
First Claim
1. A light modulator comprising:
- an input optical fiber;
a polarization separator that separates incident light from the input optical fiber into two polarization components along separate paths within the modulator;
a solid-state electro-optic PLZT phase retarder having electrodes that provide an electric field across the paths, said electric field in said phase retarder producing relative phase retardation with respect to the two polarization components from the separator;
a polarization recombiner that combines the polarization components from the retarder to form a modulated optical signal;
an output fiber optically coupled to the recombiner and that receives the modulated optical signal; and
an optical sensor that is optically coupled such that the sensor receives at least a portion of the modulated optical signal, the sensor providing a feedback signal that controls the modulator.
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Accused Products
Abstract
An optical modulator is provided to control the intensity of a transmitted or reflected light. In a transmission mode, a separator splits arbitrarily polarized light into two polarization rays and one is made to travel a separate path from the other. A recombiner causes the two rays to recombine at an output unless an electro-optic phase retarder changes the polarization of the two rays, in which case, both of them miss the output by an amount which is a function of the voltage on the retarder. A normally-off version with low polarization mode dispersion is obtained by changing the orientation of the recombiner. A normally-on version with low polarization mode dispersion is obtained with a passive polarization direction rotator. Similar results can be obtained in a reflection mode where the input and output are on the same side of the modulator. Versions using a GRIN lens are particularly suited to modulation of light out of and back into fiber-optic cables. The device can be operated as a variable optical attenuator, an optical switch, or a high speed modulator and is insensitive to polarization of the input light. A preferred material for the phase retarder is a hot-pressed ceramic lead lanthanum zirconate titanate composition.
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Citations
10 Claims
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1. A light modulator comprising:
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an input optical fiber;
a polarization separator that separates incident light from the input optical fiber into two polarization components along separate paths within the modulator;
a solid-state electro-optic PLZT phase retarder having electrodes that provide an electric field across the paths, said electric field in said phase retarder producing relative phase retardation with respect to the two polarization components from the separator;
a polarization recombiner that combines the polarization components from the retarder to form a modulated optical signal;
an output fiber optically coupled to the recombiner and that receives the modulated optical signal; and
an optical sensor that is optically coupled such that the sensor receives at least a portion of the modulated optical signal, the sensor providing a feedback signal that controls the modulator. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of modulating an optical signal comprising:
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coupling light from an input optical fiber to a polarization separator to separate the light into a plurality of polarization components;
applying an electric field in a direction across an optical path of the polarization components with a solid state electro-optic PLZT phase retarder to provide relative phase retardation between the components;
combining the polarization components to form a modulated output signal.
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Specification