Abstract: Whispering gallery mode (WGM) optical resonators comprising nonlinear optical materials, where the nonlinear optical material of a WGM resonator includes a plurality of sectors within the optical resonator and nonlinear coefficients of two adjacent sectors are oppositely poled.

Abstract: RF and microwave devices and techniques are disclosed for processing RF and microwave signals by using (1) photonic or optical components and (2) RF and microwave components. In some implementations, a part of the processing is performed in the RF and microwave domain such as applying a microwave or RF input signal to control an optical modulator ,and another part of the processing is performed in the optical domain such as optical filtering of the modulated optical beam to select desired microwave or RF spectral components. The frequency of a selected spectral component can be tuned by either tuning the frequency of the optical beam that is modulated by the optical modulator or a filter that is used to filter modulated optical beam.

Abstract: An opto-electronic oscillator including a modulator for outputting modulated light and a tunable filter for receiving modulated light output from the modulator.

Abstract: Whispering gallery mode (WGM) optical resonators formed of radiation-sensitive materials to allow for permanent tuning of their resonance frequencies in a controlled manner. Two WGM resonators may be cascaded to form a composite filter to produce a second order filter function where at least one WGM resonator is formed a radiation-sensitive material to allow for proper control in the overlap of the two filter functions.

Abstract: Tunable optical filters using whispering-gallery-mode (WGM) optical resonators-are described. The WGM optical resonator in a filter exhibits an electro-optical effect and hence is tunable by applying a control electrical signal.

Abstract: Devices and techniques for achieving signal filtering in RF or microwave frequencies by optical filtering via two optical resonators in two separate optical paths. One optical resonator is tunable to tune the filtering in RF or microwave frequencies. Tunable opto-electronic oscillators may be constructed based on described filters.

Abstract: Whispering gallery mode optical resonators which have spatially-graded refractive indices. In one implementation, the refractive index spatially increases with a distance from an exterior surface of such a resonator towards an interior of the resonator to produce substantially equal spectral separations for different whispering gallery modes. An optical coupler may be used with such a resonator to provide proper optical coupling.

Abstract: Devices with two or more coupled resonators to produce narrow spectral responses due to interference of signals that transmit through the resonators and techniques for operating such devices to achieve certain operating characteristics are described. The devices may be optical devices where optical resonators such as whispering gallery mode resonators may be used. In one implementation, at least one of the coupled optical resonators is a tunable resonator and is tuned to change its resonance frequency to tune the spectral response of the device. The described devices and techniques may be applied in optical filters, optical delays, optical waveform generators, and other applications.

Abstract: Systems and techniques of incorporating an optical resonator in an optical part of a feedback loop in opto-electronic oscillators. This optical resonator provides a sufficiently long energy storage time and hence to produce an oscillation of a narrow linewidth and low phase noise. Certain mode matching conditions are required. For example, the mode spacing of the optical resonator is equal to one mode spacing, or a multiplicity of the mode spacing, of an opto-electronic feedback loop that receives a modulated optical signal and to produce an electrical oscillating signal.

Abstract: This application describes use of an opto-electronic feedback in oscillators to suppress phase noise based on the high Q factor of the opto-electronic feedback.

Abstract: Optical filters having at least two coupled whispering-gallery-mode (WGM) optical resonators to produce a second order or higher order filter function with a desired spectral profile. At least one of the coupled WGM optical resonators may be tunable by a control signal to adjust the filtering function.

Abstract: This application describes examples and implementations of optical devices and techniques based on use of whispering gallery mode (WGM) optical resonators that have nonlinear optical materials in multiple sectors where nonlinear coefficients of two adjacent sectors are oppositely poled.

Abstract: Devices based on a non-spherical whispering-gallery-mode optical resonator.

Abstract: Techniques and devices using whispering gallery mode (WGM) optical resonators, where the optical materials of the WGM resonators exhibit an electro-optical effect to perform optical modulation. Examples of actively mode-locked lasers and other devices are described.

Abstract: Systems and techniques of incorporating an optical resonator in an optical part of a feedback loop in opto-electronic oscillators. This optical resonator provides a sufficiently long energy storage time and hence to produce an oscillation of a narrow linewidth and low phase noise. Certain mode matching conditions are required. For example, the mode spacing of the optical resonator is equal to one mode spacing, or a multiplicity of the mode spacing, of an opto-electronic feedback loop that receives a modulated optical signal and to produce an electrical oscillating signal.

Abstract: Systems and techniques of incorporating an optical resonator in an optical part of a feedback loop in opto-electronic oscillators. This optical resonator provides a sufficiently long energy storage time and hence to produce an oscillation of a narrow linewidth and low phase noise. Certain mode matching conditions are required. For example, the mode spacing of the optical resonator is equal to one mode spacing, or a multiplicity of the mode spacing, of an opto-electronic feedback loop that receives a modulated optical signal and to produce an electrical oscillating signal.

Abstract: A fiber-coupled laser based on a whispering-gallery-mode resonator formed of a laser gain medium and an angle-polished fiber coupler.

Abstract: Devices based on a non-spherical whispering-gallery-mode optical resonator.

Abstract: A fiber-coupled laser based on a whispering-gallery-mode resonator formed of a laser gain medium and an angle-polished fiber coupler.

Abstract: An electro-optical oscillator includes an electro-optical modulator having an electrical input port that accepts an electrical control signal and an optical output port. The electro-optical modulator is operable to generate at the optical output port an optical signal that oscillates at a frequency related to the electrical control signal. The oscillator also includes a photodetector that converts a portion of the optical signal from the optical output port of the electro-optical modulator to an electrical signal and provides the electrical signal to the electrical input port of the electro-optical modulator as the electrical control signal. An open loop gain of a feedback loop including the optical output port, the photodetector and the electrical input port is greater than one.