Abstract: A system for filtering light propagating in a waveguide is described. The system utilizes an adjustable periodic grating which induces mode coupling of predetermined frequencies of light propagating in the waveguide.

Abstract: Tunable PMD emulators and compensators for producing different PMD profiles with an adjustable average DGD value.

Abstract: Devices and techniques for generating and analyzing states of polarization in light using multiple adjustable polarization rotators in various applications.

Abstract: Optical devices with folded optical paths to reduce size of optical devices and optical elements in the optical devices. The folded optical paths operate by manipulating optical polarization of light. Exemplary optical switches and variable optical attenuators are described.

Abstract: Techniques and devices for depolarizing light and producing a variable differential group delays in optical signals. In one implementation, an input optical beam is split into first and second beams with orthogonal polarizations. One or two optical reflectors are then used to cause the first and second optical beams to undergo different optical path lengths before they are recombined into a single output beam. An adjustment mechanism may used implemented to adjust the difference in the optical path lengths of the first and second beams to produce a variable DGD. When the depolarization of light is desired, the difference in the optical path lengths of the first and second beams is set to be greater than the coherence length of the input optical beam.

Abstract: Techniques and systems for dynamically controlling polarization of an optical signal by using various feedback controls, and by combining both feed-forward and feedback controls. Various dynamic control algorithms for such systems and other optical systems have been disclosed.

Abstract: This application describes optical monitoring devices and applications in optical systems for monitoring various optical parameters of light, including the signal to noise ratio, the degree of polarization, and the differential group delay (DGD).

Abstract: An optical device including a beam splitter, polarization controller, and beam combiner is described. In some embodiments, the beam splitter and beam combiner are provided in a single element. An incoming light beam is split into two beams with different polarization components. The polarization of one or both of the beams is rotated using one or two polarization controllers such as fiber squeezers. The beams are then combined, so that a portion of each of the beams is provided to an output. The polarization dependent loss of the device can then be controlled by controlling the polarization rotation. In some embodiments, the rotation is dynamically controlled.

Abstract: Devices and techniques for monitoring spectrum of light. For example, a fiber spectral monitoring device and associated technique are described for monitoring spectral information in light based on an interferometer design.

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: Implementations of a polarization control method and apparatus are provided. In one implementation, a device uses super-polished squeezing surfaces to apply pressure against a polyimide coated fiber thereby minimizing micro-bending effects that cause losses in the fiber. Special control circuitry may be used to maintain a driving source of piezo-electrics that control the squeezing surfaces at a resonant frequency, thereby minimizing the voltages needed to drive the piezo-electrics.

Abstract: In-line optical polarimeters and techniques for calibrating such polarimeters are described. In one implementation a polarimeter integrates components in free space to enhance device performance.

Abstract: A system for filtering light propagating in a waveguide is described. The system utilizes an adjustable periodic grating which induces mode coupling of predetermined frequencies of light propagating in the waveguide.

Abstract: Implementations of a polarization control method and apparatus are provided. In one implementation, a device uses super-polished squeezing surfaces to apply pressure against a polyimide coated fiber thereby minimizing micro-bending effects that cause losses in the fiber. Special control circuitry may be used to maintain a driving source of piezo-electrics that control the squeezing surfaces at a resonant frequency, thereby minimizing the voltages needed to drive the piezo-electrics.

Abstract: A system for filtering light propagating in a waveguide is described. The system utilizes an adjustable periodic grating which induces mode coupling of predetermined frequencies of light propagating in the waveguide.

Abstract: Optical frequency-division filters for multiplexing and demultiplexing operations by combining wavelength-selective filtering and polarization properties of optical signals.

Abstract: Techniques and systems for monitoring a difference between the frequency of a laser and a resonance of a birefringent optical resonator. A feedback control loop may be used to lock the laser to the resonator, or alternatively, to lock the optical resonator to the laser.

Abstract: A system for filtering light propagating in a waveguide is described. The system utilizes an adjustable periodic grating which induces mode coupling of predetermined frequencies of light propagating in the waveguide.

Abstract: Optical variable delay devices for providing variable true time delay to multiple optical beams simultaneously. A ladder-structured variable delay device comprises multiple basic building blocks stacked on top of each other resembling a ladder. Each basic building block has two polarization beamsplitters and a polarization rotator array arranged to form a trihedron; Controlling an array element of the polarization rotator array causes a beam passing through the array element either going up to a basic building block above it or reflect back towards a block below it. The beams going higher on the “ladder”experience longer optical path delay. An index-switched optical variable delay device comprises of many birefringent crystal segments connected with one another, with a polarization rotator array sandwiched between any two adjacent crystal segments.

Abstract: Optical variable delay devices for providing variable true time delay to multiple optical beams simultaneously. A ladder-structured variable delay device comprises multiple basic building blocks stacked on top of each other resembling a ladder. Each basic building block has two polarization beamsplitters and a polarization rotator array arranged to form a trihedron; Controlling an array element of the polarization rotator array causes a beam passing through the array element either going up to a basic building block above it or reflect back towards a block below it. The beams going higher on the “ladder” experience longer optical path delay. An index-switched optical variable delay device comprises of many birefringent crystal segments connected with one another, with a polarization rotator array sandwiched between any two adjacent crystal segments.