A tunable interferometer for creating gratings of variable periodicity in an optical waveguide is disclosed. The interferometer includes a beam splitter for producing first and second write beams from an input beam. First and second reflectors receive the first and second write beams, respectively, from the beam splitter and direct the first and second write beams to intersect at a fixed location. The angle of intersection of the first and second write beams is a function of impingement location...

Methods and system for compensating for effects of changes and variations of gas refractivity in a measurement and/or reference beam path of an interferometer are disclosed.

Apparatus for measuring angular changes in the direction of travel of a light beam comprising at least one beam shearing assembly for separating, preferably orthogonally polarized, components of the light beam and introducing a lateral shear between them. An analyzer operates on the components to provide them with a common polarization state. A lens focuses the commonly polarized components of the light beam to a spot in a detector plane, and a detector operates to generate an electrical signal ...

Method and assembly for sustained elimination or reduction of polarization induced signal fading in optical interferometer networks comprising at least two optical paths from an input port to an output port, the transmission delays of the paths differing by .tau., an interrogation arrangement interrogating the optical phase differences between the paths, containing at least one optical source launching optical power into a port, a detector arrangement converting the optical power from an output ...

An optical signal rejection filter has a beam separator giving light waves with two different transmission devices and with different propagation times. Optoelectronic detectors receive these waves and give equivalent electrical signals to a differential amplifier which gives a signal representing the difference between the signals received. This filter can be used, preferably, in ring interferometers.

Unbalanced Mach-Zehnder interferometers (MZI) are useful for a number of applications including wavelength filters, gain flattening or gain equalization elements, and band splitters or combiners. A MZI is comprised of two couplers surrounding a phase shifting region, which consists of two arms with differential propagation constants. We disclose a means of using light exposure to unbalance a symmetric MZI consisting of substantially the same lengths of substantially the same fiber. In particular...

An optical apparatus for reading from and writing to an ultra high density disk and comprising a light source emitting a pencil of light rays to an optical path along an optical axis; two interferometers, a beamsplitter, a quarter-wave plate, and an objective lens. The pencil of light rays is transmitted through the apparatus to become a narrow fringe ring which in turn is used to generate an ultra small spot of light. The resulting ultra small spot of light can address far more storage location...

Negative group-delay-dispersion mirror (NGDD-mirror) multilayered structures are formed by two interferentially coupled Gires-Tournois interferometer cavities on a common, highly-reflective mirror in a single monolithic multilayered structure.

A measuring arrangement is disclosed for measuring the contour of a two or three dimensional surface in which a redundant configuration of distance measuring systems is positioned above the surface being measured. Each distance measuring system monitors distance measurements to a point proximate the surface as the measuring point is moved across the surface. The distance measurements are taken from a sufficient number of points on the surface such that a sufficient quantity of data is obtained t...

To measure the coherence length of light, an incident beam (20) is caused to interfere with replicas of itself after having variable delays. Variable delays are generated by passing a beam (40) that is a part of the incident beam (20) around a loop (46). The beam partially leaves the loop (46) at each cycle and partially continues looping. A beam (44) with multiple delays leaving from the loop (46) is caused to interfere with a beam (56) that is another part of the incident beam (20) without del...