Abstract: A material having a surface and a dopant in the material distributed whereby the material has a spatially variant optical flux density profile. In accordance with the invention, tailored non-uniform gain profiles within a Yb:YAG laser component (rod, slab, disc, etc.) are achieved by a spatial material modification in the spatially masked pre-forms. High temperature-assisted reduction leads to the coordinate-dependent gain profiles, which are controlled by the topology of the deposited solid masks. The gain profiles are obtained by reducing the charge state of the laser-active trivalent Yb3+ ions into inactive divalent Yb2+ ions. This valence conversion process is driven by mass transport of ions and oxygen vacancies. These processes, in turn, affect the dopant distribution throughout the surface and bulk laser crystal. By reducing proportionally more Yb3+ ions at the unmasked areas of component, than in the masked areas, the coordinate-dependent or spatially-controlled gain profiles are achieved.

Abstract: A beam control system and method: The inventive system includes, an arrangement for receiving a first beam of electromagnetic energy; measuring wavefront aberrations in the first beam with a wavefront sensor; and removing global tilt from the measured wavefront aberrations to provide higher order aberrations for beam control. In the illustrative embodiment, the invention uses a traditional (quad-cell) Shack-Hartmann wavefront sensor to measure wavefront aberrations. An adaptive optics processor electronically removes the global tilt (angular jitter) from this measurement leaving only the higher-order Zernike components. These higher-order aberrations are then applied to wavefront control elements, such as deformable mirrors or spatial light modulators that correct the tracker image and apply a conjugate distortion to the wavefront of the outgoing HEL beam. A track error (angular jitter) component is supplied by a separate fine track sensor.

Abstract: A phase conjugate mirror comprising a photonic band gap light guide and a stimulated Brillouin scattering medium disposed in operational relation thereto. In specific embodiments, the light guide is an optical fiber with a high index cladding transparent at a propagation wavelength and a hollow or solid core. The cladding is microstructured silica and supports guide modes through frustrated tunneling photonic band gap guidance or Bragg photonic band gap guidance. The fiber has an array of channels disposed around the core. In one embodiment, the fiber is disposed within a stimulated Brillouin scattering cell. In this embodiment, the medium is gas, gel, or liquid. In an alternative embodiment, the medium is a solid disposed at the core of the fiber. The invention provides a means of guiding light with a gas filled or solid core structure with high guiding efficiency, high reflection back into the medium, without disturbing the polarization state of the light as it propagates.

Abstract: A laser resonator for generating a laser beam having beam quality along two transverse axes that is determined primarily by the mode discrimination characteristics of one axis. The apparatus including a means for providing a collimated beam of electromagnetic energy with a predetermined orientation with respect to a line of sight thereof, and, a means for rotating the beam such that a transverse mode selection therefor is the same for two orthogonal directions thereof. The first means includes a slab laser having principal axes, and the second means includes a porro prism or a Benson prism. The prism is rotated 45 degrees about the line of sight with respect to the slab axes. The beam is rotated through successive round trip passes through the slab. A telescope, or an anamorphic telescope may be disposed between the slab and the prism. The resonator has a high aspect ratio slab lasing medium with a first and a second end that emit a laser beam.

Abstract: A spatial filter adapted to increase the angular spread of non-conjugated energy in a beam and suppress this energy to improve the efficiency of a phase conjugate system. In the illustrative embodiment, the filter includes first and second lenses and an aberrator to increase the angular spread. In the specific embodiment, an opaque plate, with a pinhole aperture therethrough, is sandwiched between the lenses to suppress the non-conjugated energy. The aberrator may be implemented with an amplifier or other suitable mechanism. Likewise, the aperture may be replaced with a highly angle-selective thick Bragg grating or other suitable arrangement. A phase conjugate master oscillator/power amplifier laser architecture is also disclosed.

Abstract: This invention uses a real-time holographic medium to record the amplitude and phase information collected from a moving platform at the aperture plane of a side-looking optical sensor over the collection time. A back-scan mirror is used to compensate platform motion during the synthetic aperture integration time. Phase errors caused by a nonlinear platform motion are compensated by controlling the phase offset between the illumination beam and the reference beam used to write the hologram based on inertial measurements of the flight path and the sensor line-of-sight pointing angles. In the illustrative embodiment, a synthetic aperture ladar (SAL) imaging system is mounted on a mobile platform. The system is adapted to receive a beam of electromagnetic energy; record the intensity and phase pattern carried by the beam; and store the pattern to compensate for motion of the platform relative to an external reference. In the illustrative embodiment, the image is stored as a holographic image.