Apparatus and method for initializing an optical-fiber laser for mode locking
First Claim
Patent Images
1. A fiber loop laser comprising:
- a fiber loop having an output coupler;
a Sagnac loop, optically coupled to the fiber loop to define an optical path, having an input coupler receiving excitation energy;
wherein the optical path includes the fiber loop and the Sagnac loop;
polarization compensation means in the optical path;
an amplifying medium in the optical path, operative to amplify a light signal in the optical path sufficiently to cause to the laser to oscillate;
wherein the output coupler extracts a portion of the amplified light signal; and
a controllable phase shifter in the optical path, operative to introduce a non-reciprocal phase shift before mode-lock to initialize the laser for mode-locking.
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Abstract
A figure-8 loop laser having a controllable phase shifter in a Sagnac loop (non-linear amplifying loop mirror). A half-wave plate in series with Faraday optical rotators provide a switchable non-reciprocal 180-degree phase shifter that allows the birefringence of the fiber loop to be adjusted during continuous wave operation. The phase shifter is activated during continuous wave operation to find a minimum threshold and then is turned off, placing the laser in optimum state for mode locking.
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Citations
18 Claims
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1. A fiber loop laser comprising:
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a fiber loop having an output coupler; a Sagnac loop, optically coupled to the fiber loop to define an optical path, having an input coupler receiving excitation energy; wherein the optical path includes the fiber loop and the Sagnac loop; polarization compensation means in the optical path; an amplifying medium in the optical path, operative to amplify a light signal in the optical path sufficiently to cause to the laser to oscillate; wherein the output coupler extracts a portion of the amplified light signal; and a controllable phase shifter in the optical path, operative to introduce a non-reciprocal phase shift before mode-lock to initialize the laser for mode-locking. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A fiber loop laser comprising:
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a single mode fiber loop including an optical isolator, a first polarization controller, and an output coupler in a series connection; a Sagnac loop including a second polarization controller, an amplifying medium operative to amplify an optical signal, an input coupler which receives excitation energy from an external source, and a controllable phase shifter in a series connection; and optical coupling means coupling the fiber loop and the Sagnac loop together. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A method of initializing a laser for mode-locking, comprising the steps of:
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introducing a non-reciprocal phase shift into the laser; placing the laser in continuous wave operation; adjusting birefringence within the laser to optimize the laser for mode-locking; introducing a reciprocal phase shift into the laser; and initiating mode-locking.
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18. A method of initializing a laser for mode-locking, comprising the steps of:
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introducing a reciprocal phase shift into the laser; placing the laser in continuous wave operation; adjusting birefringence within the laser to optimize the laser for mode-locking; introducing a non-reciprocal phase shift into the laser; and initiating mode-locking.
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Specification