Abstract: A method and circuit are presented for the all optical recovery of the clock signal from an arbitrary optical data signal. The method involves two stages. A first stage preprocesses the optical signal by converting a NRZ signal to a PRZ signal, or if the input optical signal is RZ, by merely amplifying it. In a preferred embodiment this stage is implemented via an integrated SOA in each arm of an asymmetric interferometric device. The output of the preprocessing stage is fed to a clock recovery stage, which consists of a symmetric interferometer that locks on to the inherent clock signal by using the second stage input signal to trigger two optical sources to self oscillate at the clock rate. In a preferred embodiment the second stage is implemented via SOAs integrated in the arms of an interferometer, with two DFB lasers as terminuses. The output of the interferometer is an optical clock signal at the clock rate of the original input.

Abstract: Advantageous methodologies are disclosed for embedding periodic patterns in optical waveguide elements such as optical fibers. Polarization independence in an elongated waist region of an add/drop coupler can be established by measuring polarization characteristics during fusion and elongation, and controlling the elongation to impart a cross-sectional shape, such as a hybrid dumbbell-ellipsoid. Polarization dependence can also be minimized by angular deformation of the elements along the light transmissive axis. To write a pattern, an element having potential photosensitivity is markedly photosensitized in a hydrogen or deuterium environment pressurized to about 1000 to 5000 psi and a scanning UV beam that is transmitted through a photo mask and impinges on the coupler waist as the in-diffused gas is constantly replenished.

Abstract: Rough machining of a glass-ceramic material article such as a radome is accomplished using a high-power Nd:YAG laser. The radome is rotated about its longitudinal axis, and the point of application of the laser beam is translated generally parallel to the longitudinal axis over either the inside or outside surface of the radome. The Nd:YAG laser preferably operates in a pulsed wave mode with a pulse duration of from about 0.3 to about 3 milliseconds, a pulse frequency of from about 50 to about 500 pulses per second, and a pulse intensity of at least about 3.times.10.sup.4 Watts per square centimeter. After laser rough machining, at least about 0.002 inches of material is removed from the rough-machined surface by a finish machining, preferably mechanical grinding.