Abstract: A parallel monitored and controlled optical PMD compensator comprises a branch optical signal split from an optical signal path. A polarization controller (PC) and differential group delay are disposed in each of the paths. A controller adjusts polarization compensation of the PCs in response to PMD dispersion of the branch optical signal. A PMD monitor is preferably disposed in the branch path providing a monitor signal to the controller for use in adjusting the PCs. A polarization rotator may inject a reference signal into the paths with the PC disposed in the branch path acting as a polarization scrambler. A state of polarization (SOP) of the reference signal may be monitored by polarimeters disposed in both paths and the SOP of the reference signal in the branch path may be provided to the controller for adjusting polarization compensation of the inline PC.

Abstract: Temperature compensated fiber stretching is accomplished by amplifying with a unique flexure the relative displacement between a rigid frame and a longitudinal spacing element. For passive compensation, relative displacement results from differential thermal expansion between the frame and the longitudinal spacer. For active thermal compensation and/or for wavelength tuning of an embedded fiber Bragg grating, relative displacement results from combining differential thermal expansion with active feedback length control of the longitudinal spacer. The feedback control can stabilize using length feedback from a displacement sensor or actively control length using temperature feedback, including logic elements, for example algorithms or look up tables. In an optical system, combined passive compensation and active control with flexure amplification provide superior thermal wavelength stability and tuning range.

Abstract: Optical interferometric techniques and systems for fabricating fiber Bragg gratings in photosensitive optical fibers by using an acousto-optic element to generate and control the radiation pattern with a high resolution. The radiation pattern may be programmable in that different radiation patterns may be produced by controlling the acousto-optic element.