Feedback-enhanced self-injection locking of lasers to optical resonators
First Claim
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1. A laser device for locking a laser to an optical whispering gallery mode resonator external to the laser based enhanced injection feedback from the resonator to the laser, comprising:
- a laser that produces a laser beam at a laser frequency;
an optical resonator structured to support whispering gallery modes circulating in the optical resonator, the optical resonator being optically coupled to the laser to receive a portion of the laser beam into the optical resonator in one or more whispering gallery modes to circulate in the optical resonator;
a first optical coupler located in an optical path of the laser beam to couple at least a portion of the laser beam into the optical resonator to circulate in the optical resonator along a first direction and to couple light, that circulates in the optical resonator along a second direction opposite to the first direction, out of the optical resonator as feedback light to the laser to stabilize the laser frequency and to reduce a linewidth of the laser;
a second optical coupler coupled to the optical resonator at a location different from a location of the first optical coupler with respect to the optical resonator, the second optical coupler to couple light in the optical resonator that circulates along the first direction out of the optical resonator as an output light beam; and
a feedback optics device located in an optical path of the output light beam output by the second optical coupler to receive the output light beam and to reflect at least a portion of the output light beam back into the second optical coupler as a reflected light beam, wherein the second optical coupler couples at least a portion of the reflected light beam into the optical resonator along the second direction to increase optical energy of light in the optical resonator that circulates along the second direction to enhance optical energy that is fed back to the laser by the first optical coupler to effectuate injection locking of the laser to the optical resonator,wherein, the feedback optics device provides a control on the injection locking and the laser frequency of the laser is locked to a resonance frequency of a whispering gallery mode of the optical resonator.
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Abstract
Techniques and devices that lock and stabilize a laser to an optical resonator via self-injection locking based on a reflection feedback. A whispering gallery mode optical resonator can be implemented to provide both the optical filtering and injection feedback based on the reflection feedback from feedback optics outside the optical resonator.
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Citations
28 Claims
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1. A laser device for locking a laser to an optical whispering gallery mode resonator external to the laser based enhanced injection feedback from the resonator to the laser, comprising:
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a laser that produces a laser beam at a laser frequency; an optical resonator structured to support whispering gallery modes circulating in the optical resonator, the optical resonator being optically coupled to the laser to receive a portion of the laser beam into the optical resonator in one or more whispering gallery modes to circulate in the optical resonator; a first optical coupler located in an optical path of the laser beam to couple at least a portion of the laser beam into the optical resonator to circulate in the optical resonator along a first direction and to couple light, that circulates in the optical resonator along a second direction opposite to the first direction, out of the optical resonator as feedback light to the laser to stabilize the laser frequency and to reduce a linewidth of the laser; a second optical coupler coupled to the optical resonator at a location different from a location of the first optical coupler with respect to the optical resonator, the second optical coupler to couple light in the optical resonator that circulates along the first direction out of the optical resonator as an output light beam; and a feedback optics device located in an optical path of the output light beam output by the second optical coupler to receive the output light beam and to reflect at least a portion of the output light beam back into the second optical coupler as a reflected light beam, wherein the second optical coupler couples at least a portion of the reflected light beam into the optical resonator along the second direction to increase optical energy of light in the optical resonator that circulates along the second direction to enhance optical energy that is fed back to the laser by the first optical coupler to effectuate injection locking of the laser to the optical resonator, wherein, the feedback optics device provides a control on the injection locking and the laser frequency of the laser is locked to a resonance frequency of a whispering gallery mode of the optical resonator. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A laser device for locking a laser to an optical whispering gallery mode resonator external to the laser based enhanced injection feedback from the resonator to the laser, comprising:
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a laser that produces a laser beam at a laser frequency; an optical resonator structured to support whispering gallery modes circulating in the optical resonator, the optical resonator being optically coupled to the laser to receive a portion of the laser beam into the optical resonator in one or more whispering gallery modes to circulate in the optical resonator; a first optical coupler located in an optical path of the laser beam to couple at least a portion of the laser beam into the optical resonator to circulate in the optical resonator along a first direction and to couple light, that circulates in the optical resonator along a second direction opposite to the first direction, out of the optical resonator as feedback light to the laser to stabilize the laser frequency and to reduce a linewidth of the laser; a second optical coupler coupled to the optical resonator at a location different from a location of the first optical coupler with respect to the optical resonator, the second optical coupler to couple light in the optical resonator that circulates along the first direction out of the optical resonator as an output light beam; and a feedback optics device located in an optical path of the output light beam output by the second optical coupler to receive the output light beam and to reflect at least a portion of the output light beam back into the second optical coupler as a reflected light beam, wherein the second optical coupler couples at least a portion of the reflected light beam into the optical resonator along the second direction to increase optical energy of light in the optical resonator that circulates along the second direction to enhance optical energy that is fed back to the laser by the first optical coupler to effectuate injection locking of the laser to the optical resonator, wherein; the first optical coupler couples a small portion of the laser beam into the optical resonator to reduce optical nonlinearity or thermal instability caused by the laser beam inside the optical resonator.
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20. A method for locking a laser to an optical whispering gallery mode resonator external to the laser based enhanced injection feedback from the resonator to the laser, comprising:
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operating a laser to produce a laser beam at a laser frequency; operating a first optical coupler to (1) couple a portion of the laser beam into an optical resonator, that is structured to support whispering gallery modes, to circulate along a first direction inside the optical resonator, and (2) couple light in the optical resonator, that circulates along a second direction opposite to the first direction, out of the optical resonator as feedback light to the laser to stabilize the laser frequency and to reduce a linewidth of the laser; operating a second optical coupler, at a location different from a location of the first optical coupler with respect to the optical resonator, to couple light in the optical resonator that circulates along the first direction out of the optical resonator as an output light beam; operating a feedback optics device located in an optical path of the output light beam output by the second optical coupler to receive the output light beam and to reflect at least a portion of the output light beam back into the second optical coupler as a reflected light beam, and to couple at least a portion of the reflected light beam into the optical resonator along the second direction to increase optical energy of light in the optical resonator that circulates along the second direction to enhance optical energy that is fed back to the laser by the first optical coupler to effectuate injection locking of the laser to the optical resonator; and configuring the feedback optics device to have a sufficiently high reflectivity to cause the feedback light to the laser to be at an optical power level above an optical power level of scattered light caused by scattering in the optical resonator. - View Dependent Claims (21, 22)
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23. A laser device for generating and locking laser light to a resonance of an optical whispering gallery mode resonator, comprising:
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a first optical reflector that reflects light; a semiconductor optical amplifier (SOA) located on one side of the first optical reflector and configured to produce an optical gain and amplify light; an optical resonator structured to support optical whispering gallery modes circulating in the optical resonator in two opposite directions, the optical resonator being optically coupled to the SOA to receive light from the SOA; a first optical coupler located to couple light from the SOA into the optical resonator to circulate in the optical resonator along a first direction and to couple light, that circulates in the optical resonator along a second direction opposite to the first direction, out of the optical resonator as feedback light to the SOA, wherein the SOA is located between the first optical reflector and the first optical coupler; a second optical coupler coupled to the optical resonator at a location different from a location of the first optical coupler with respect to the optical resonator, the second optical coupler to couple light in the optical resonator that circulates along the first direction out of the optical resonator as an output light beam; and a feedback optics device located in an optical path of the output light beam output by the second optical coupler to receive the output light beam and to include a second reflector reflects at least a portion of the output light beam back into the second optical coupler as a reflected light beam, wherein the second optical coupler couples at least a portion of the reflected light beam into the optical resonator along the second direction to increase optical energy of light in the optical resonator that circulates along the second direction to enhance optical energy that is fed back to the SOA by the first optical coupler to effectuate a laser resonator formed by the first and second optical reflectors to produce laser light, wherein the optical resonator is a tunable resonator that changes a frequency of the resonator in response to a control signal to tune a frequency of the laser light while the feedback optics device operates to effectuates enhanced optical feedback light to the SOA to reduce a lasing threshold of the laser device. - View Dependent Claims (24, 25, 26, 27, 28)
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Specification