Abstract: A laser provides light of a first frequency .omega.+.DELTA. along a first optical path, the light being focused by optics onto a target disposed at the primary focal plane of the optics. A laser amplifier is disposed along a second optical path which receives light reflected from the target and processed through a portion of the optics. This amplifier transmits, substantially unamplified, light at the first frequency .omega.+.DELTA. and amplifies light substantially at a second frequency .cndot.. Phase conjugation apparatus is disposed along the second optical path and provides light which is the phase conjugate of light incident thereupon. The phase conjugated light is provided at the second frequency .omega. and directed back through the laser amplifier for amplification thereof and through the optics to the target.

Abstract: An autopointing laser system utilized in the tracking and/or detection of objects having a stationary flat reflector, a pair of parabolic reflectors, and a telescope reflector, all in optical alignment with each other. When the telescope reflector is also in optical alignment with the object to be tracked and/or detected these elements combine to act as the optical resonator of the laser system. As a result of the above arrangement, the lasing medium located between the pair of parabolic reflectors will continue to oscillate as long as the object remains in the field of view of the telescope reflector thereby providing an automatic tracking operation.

Abstract: There is disclosed an angle selective coupler for coupling optical energy into and/or out of optical fibers. The coupler consists of a section of the optical fiber modified in such a way as to allow optical excitation of a plurality of higher order modes of optical transmission, each mode being defined by a given angle of propagation relative to the fiber axis. In one embodiment the coupling section comprises a single strand of glass fiber waveguide which is tapered along its length. The existence of the tapered section allows coupling of radiation from an external source into a given propagation angle in the fiber. In another embodiment no taper is used, but the fiber cladding is etched down to a thin layer and higher index material is deposited over the thin layer. This allows coherent coupling of radiation into one or more higher order modes in the optical fiber as determined by the angle of the incident light beam with respect to the cladding of the fiber.