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US 7,362,927 B1Granted
Tunable RF or microwave photonic filters using temperature-balanced whispering gallery mode optical resonators
AssigneeOEwaves, Inc.
InventorsVladimir Ilchenko, Dmitri A. Kossakovski, Ismail Tolga Yilmaz, Danny Eliyahu, Nikolai Morozov, Mark Henderson
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Abstract
Devices and techniques for filtering RF or microwave frequencies by optical filtering using a tunable optical filter.
Claims20
A device, comprising:
- a laser comprising a laser resonator, an optical gain medium in the laser resonator, and a whispering gallery mode (WGM) optical resonator in the laser resonator with a resonance at a laser carrier frequency to filter laser light in the laser resonator;
- an optical coupler to split the laser beam out of the laser into a first laser beam and a second laser beam;
- an optical modulator to receive the first laser beam and an input electrical signal, the optical modulator to modulate the first laser beam in response to the input electrical signal to produce a modulated optical beam carrying optical sidebands at optical frequencies different from the laser carrier frequency;
- a second WGM optical resonator to receive the modulated optical beam, tunable to change in frequency in response to a resonator control signal to filter the modulated optical beam by selecting one of the optical sidebands to transmit as a filtered optical signal and rejecting other optical sidebands and the laser carrier frequency;
- and
- an optical detector to receive the filtered optical signal and the second optical beam and to produce an output signal carrying signal information in the selected optical sideband at a frequency equal to a difference between the laser carrier frequency and an optical frequency of the selected optical sideband.
3 more elements
A method, comprising:
- placing first and second whispering gallery mode (WGM) optical resonators on a common base to be close to each other so that resonances of the first and second WGM optical resonators drift together with temperature to be thermally stable relative to each other;
- using the first WGM optical resonator as a filter inside a laser resonator of a laser to filter laser light in the laser resonator to be at a laser carrier frequency;
- splitting a laser beam out of the laser into a first laser beam and a second laser beam;
- applying an input RF or microwave signal to an optical modulator to modulate the second laser beam to produce a modulated beam that carries the input RF or microwave signal as optical sidebands at optical frequencies different from the laser carrier frequency;
- directing the modulated beam through the second WGM optical resonator to produce a filtered optical beam;
- tuning a resonance frequency of the second WGM optical resonator to select one of the optical sidebands in the modulated beam and to reject other optical sidebands and the laser carrier frequency so that the filtered optical beam has only the selected optical sideband;
- and
- using an optical detector to combine and detect the filtered optical beam and the first optical beam and to produce an output signal carrying signal information in the selected optical sideband at an RF or microwave frequency equal to a difference between the laser carrier frequency and an optical frequency of the selected optical sideband.
5 more elements
A device, comprising:
- a laser to produce a laser carrier beam at a laser carrier frequency and comprising a whispering gallery mode (WGM) optical resonator inside the laser to control the laser carrier frequency;
- an optical coupler to split the laser carrier beam out of the laser into a first laser beam and a second laser beam;
- an optical modulator to modulate the first laser beam in response to an input electrical signal to produce a modulated optical beam carrying optical sidebands at optical frequencies different from the laser carrier frequency;
- a second WGM optical resonator, placed in a close proximity with and thermally coupled to the WGM optical resonator, to receive the modulated optical beam and tunable to select one of the optical sidebands to output a filtered optical signal with only the selected one optical sideband;
- and
- an optical detector to receive the filtered optical signal and the second optical beam and to produce an output signal carrying signal information in the selected one optical sideband at a frequency equal to a difference between the laser carrier frequency and an optical frequency of the selected one optical sideband.
3 more elements
Dependencies are inferred from the claim text.