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: This application describes devices and techniques for dynamically controlling polarization light at one or more locations along the optical transmission path to reduce optical noise and PMD in the optical signal. One device according to an implementation includes a polarization controller to receive an optical signal and operable to control polarization of the optical signal in response to a control signal, a fixed optical polarizer to receive output from the optical polarization controller and to produce an output optical signal, and a circuit to receive a fraction of the output optical signal from the fixed optical polarizer and operable to produce the control signal in response to an output power level of the output optical signal which controls the polarization controller to maximize the output power level.

Abstract: Devices and their operations to use multiple adjustable differential group delay (DGD) elements in various applications including tunable PMD emulators and compensators for producing different PMD profiles with an adjustable average DGD value.

Abstract: Techniques and devices that use polarization rotation and optical interferometry to provide optical spectrum analysis of an optical signal.

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: Devices and techniques that use a polarization controller and a feedback control to the polarization controller to systematically control the polarization of light output from the polarization controller in measuring the polarization dependent loss (PDL) of an optical device or material that receives the light from the polarization controller or the degree of polarization (DOP) of a light beam directed into the polarization controller.

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: Devices and techniques that use a polarization controller and a feedback control to the polarization controller to systematically control the polarization of light output from the polarization controller in measuring the polarization dependent loss (PDL) of an optical device or material that receives the light from the polarization controller or the degree of polarization (DOP) of a light beam directed into the polarization controller.

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

Abstract: Polarimeters based on transversal division of the input beam and use of different polarization elements in different polarization states to change polarizations of different portions of the input beam so that the power levels of the different portions of the input beam can be measured to determine the polarization state of the input beam. A wedged substrate can be used to direct the different portions of the input beam at different directions and a lens can be used to focus these different portions at different locations at a plane.

Abstract: This application describes techniques for optical multiplexing and demultiplexing in optical communication systems based on polarization multiplexing of different signal channels.

Abstract: Techniques and devices for monitoring polarization of light using at least two polarization elements where the difference between the outputs of the two polarization elements are used to monitor a change in polarization.

Abstract: This application teaches various implementations of methods and in-line polarimeters with free-space sampling elements to sample four sample beams for determining the polarization state of input light. In one exemplary implementation, a device in this application includes four optical polarization analyzers arranged in series to form an optical path in free space to split four sample beams with four different states of polarization from an input optical beam propagating along the optical path. Each optical polarization analyzer transmits a majority of the input optical beam along the optical path and splits a fraction of the input beam as a respective sample beam. The device also includes four optical detectors respectively positioned in optical paths of the four sample beams to convert the sample beams into four detector signals indicative of optical power levels of the four different states of polarization, respectively.

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.