Abstract: In various examples, a semi-guiding optical fiber includes a core having a high aspect ratio including first and second wide surface interfaces, and first and second narrow edge interfaces. The core has a slow axis parallel to the first and second wide surface interfaces, and a refractive index. The fiber also includes first and second signal claddings positioned in contact with the first and second wide surfaces of the core, respectively. The first and second signal claddings have a spatial refractive index profile having: i) a minimum value at a longitudinal axis of the core, ii) a maximum value substantially equal to the refractive index of the core at the first and second narrow edge interfaces of the core, and iii) intermediate values gradually increasing from the minimum value to the maximum value as distance from the longitudinal axis increases along the slow axis of the fiber.

Abstract: In various embodiments, a semi-guiding optical fiber includes a core having a first refractive index and a high aspect ratio elongated cross-section along a slow axis direction. First and second signal claddings having a second refractive index sandwich the core. A third cladding having a third refractive index substantially surrounds at least side edges of the core. The first refractive index of the core, the third refractive index of the third cladding, and/or the second refractive index of the first and second signal claddings, are selected so as to maximize a differential loss between a lowest order mode propagating in the optical fiber and next order modes so as to discriminate in favor of the lowest order mode and against the next order modes.

Abstract: In various examples, a semi-guiding optical fiber includes a core having a high aspect ratio including first and second wide surface interfaces, and first and second narrow edge interfaces. The core has a slow axis parallel to the first and second wide surface interfaces, and a refractive index. The fiber also includes first and second signal claddings positioned in contact with the first and second wide surfaces of the core, respectively. The first and second signal claddings have a spatial refractive index profile having: i) a minimum value at a longitudinal axis of the core, ii) a maximum value substantially equal to the refractive index of the core at the first and second narrow edge interfaces of the core, and iii) intermediate values gradually increasing from the minimum value to the maximum value as distance from the longitudinal axis increases along the slow axis of the fiber.

Abstract: An optical pulse shaper includes an optical delay line; a spatial light modulator placed at the Fourier plane of the optical delay line having a spectral amplitude spatial light modulator; a spectral phase and polarization ellipticity spatial light modulator; and a spectral polarization rotator; and a controller configured to independently control an amplitude, a phase and polarization ellipticity, and a linear polarization of an optical pulse. A method for shaping an optical pulse is also provided.

Abstract: An optical pulse shaper includes an optical delay line; a spatial light modulator placed at the Fourier plane of the optical delay line having a spectral amplitude spatial light modulator; a spectral phase and polarization ellipticity spatial light modulator; and a spectral polarization rotator; and a controller configured to independently control an amplitude, a phase and polarization ellipticity, and a linear polarization of an optical pulse. A method for shaping an optical pulse is also provided.

Abstract: In various embodiments, a semi-guiding optical fiber includes a core having a first refractive index and a high aspect ratio elongated cross-section along a slow axis direction. First and second signal claddings having a second refractive index sandwich the core. A third cladding having a third refractive index substantially surrounds at least side edges of the core. The first refractive index of the core, the third refractive index of the third cladding, and/or the second refractive index of the first and second signal claddings, are selected so as to maximize a differential loss between a lowest order mode propagating in the optical fiber and next order modes so as to discriminate in favor of the lowest order mode and against the next order modes.

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.

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: A solid-state laser beam amplifier with integrated reflective surface. A rectangular slab gain medium receives a first portion of an input laser beam along a first zigzag reflection path within the slab. The gain medium also receives a second portion of the input laser beam that has been reflected from an integral reflective surface such that the two portions traverse the gain medium along complementary zigzag paths. The zigzag paths are defined by total internal reflection of the beam portions as they propagate through the gain medium slab. A similar reflective surface may be positioned relative to the exit end of the gain medium slab, which redirects all of the output beam portions in a parallel direction. The gain medium may be Ytterbium or neodymium doped yttrium aluminum garnet. The gain medium may be formed as a high aspect ratio rectangular slab and may be clad with sapphire.

Abstract: A solid-state laser beam amplifier with integrated reflective surface. A rectangular slab gain medium receives a first portion of an input laser beam along a first zigzag reflection path within the slab. The gain medium also receives a second portion of the input laser beam that has been reflected from an integral reflective surface such that the two portions traverse the gain medium along complementary zigzag paths. The zigzag paths are defined by total internal reflection of the beam portions as they propagate through the gain medium slab. A similar reflective surface may be positioned relative to the exit end of the gain medium slab, which redirects all of the output beam portions in a parallel direction. The gain medium may be Ytterbium or neodymium doped yttrium aluminum garnet. The gain medium may be formed as a high aspect ratio rectangular slab and may be clad with sapphire.

Abstract: The inventive rod includes a gain medium having first and second equal length portions sharing a common optical axis and an optical rotator disposed between said first and second portions which optical rotator compensates for birefringence. In an exemplary case, the optical rotator includes first and second waveplates optically coupled to one another and oriented with respect to one another by a predetermined angle, where the first waveplate receives a polarized beam having a first state, and the second waveplate produces the polarized beam having a second state, the first and second states differing from one another by 90°. Multiple rotators can be employed to compensate strongly birefringent rods, each rotator compensating a section of a rod constructed from a plurality of equal length optical gain elements.

Abstract: A system (10) for rotating a polarization state of a beam of electromagnetic energy (22) of the present invention. The system (10) includes a first mechanism (16) for receiving the beam of electromagnetic energy (22). The beam of electromagnetic energy (22) is characterized by a first arbitrary polarization state oriented at a first angle. A second mechanism (16, 18, 20) orients the first arbitrary polarization state, via one or more waveplates (16, 18, 20), at a second angle that is different from the first angle. In a specific embodiment, the one or more waveplates (16, 18, 20) include a first quarter waveplate (16) having a principal axis (26) angled at 45° from horizontal relative to a given reference frame. A second quarter waveplate (20) is angled at −45°.

Abstract: A thermal birefringence compensator for a double pass laser system, which includes a polarization or conventionally outcoupled laser resonator, a gain medium and a compensator optically coupled to the gain medium. In one implementation, the compensator, which acts as an end reflector, includes a Benson prism, a first quarter waveplate with its principle axes aligned to the fold axis of the Benson prism, and a second quarter waveplate with its principle axes at 45° to the fold axis of the Benson prism. Alternatively, the compensation's prism can be a Porro prism.

Abstract: An optical rotator includes a pair of waveplates which receive a polarized beam having a first state and outputs a polarized beam having a second state rotated 90° with respect to the first state. In the illustrative embodiment, the first and second waveplates are physically coupled to one another.

Abstract: A laser pump cavity apparatus with integral concentrator provides uniform gain and high absorption efficiency. The apparatus has a doped solid-state laser medium, a concentrator which has a top cladding layer formed on the top surface of the doped laser medium having a cylindrical focusing surface, a bottom cladding layer formed on the bottom surface of the doped laser crystal having a cylindrical focusing surface, and edge cladding layers formed on the side surfaces of the doped laser medium. Cold plates, each of which also preferably has one cylindrical surface of substantially identical shape, are placed in thermal contact with the cylindrical focusing surfaces of the top and bottom cladding layers to absorb heat. The cylindrical focusing surfaces preferably have hyperbolic or quasi-hyperbolic shape. The laser pump cavity apparatus is preferably edge-pumped with several laser diode arrays focused toward the line foci of the cylindrical focusing surfaces in directions transverse to a laser beam axis.

Abstract: A laser crystal (25) having a relatively short optical length functions as a seed laser (1) and simultaneously establishes the wide separation between longitudinal modes. Pulsed operation causes multiple longitudinal modes to co-exist before competition acts to extinguish modes. The seed laser (1) is isolated from the relatively higher peak power output beam (4). Further, the injection seeded slave resonator (6) optical cavity length is adjusted by mechanical, electromechanical and/or electro-optical component(s) to harmonize the slave resonator optical cavity to the seed laser (1) optical cavity. A number of widely separated longitudinal modes are simultaneously output as a pulsed, high optical quality beam having a broad frequency range, short temporal coherence, and stable simultaneous operation of the several modes.

Abstract: An improved electro-optic modulator having reduced amplitude of acoustic resonances is provided. Acoustic energy is efficiently removed from the electro-optic crystal and channeled into electrode and side dielectric bars where it is dissipated by materials acoustically matched to the electro-optic crystal, that is, materials that have acoustic impedances within .+-.15% of that of the electro-optic material.

Abstract: A waveguide coupler for coupling electromagnetic power between a first rectangular waveguide and a second rectangular waveguide includes a one-dimensional intermediate waveguide formed of two plates spaced apart by a distance equal to a common height of the two waveguides. This enables a wave emanating from the first waveguide to spread apart transversely so as to equal the width of the second waveguide, the width of the second waveguide being greater than the width of the first waveguide. A cylindrical lens is located between the intermediate waveguide and the second waveguide to provide for a conversion between a cylindrical wavefront and a planar wavefront. The coupler is operative in reciprocal fashion such that a wave emanating from the first waveguide spreads out in width and is then converted to a planar waveguide prior to entering the second waveguide; and a wave emanating from the second waveguide is converted to a wave of contracting width for entry into the first waveguide.

Abstract: This invention discloses a narrow field of view scanner (10) incorporating two multi-faceted polygon scanning wheels (12, 16) having a slightly different number of facets (14, 18). Each scanning wheel (12, 16) turns at an angular rate such that a facet (14) on one wheel (12) rotates through a predetermined field of view at the same rate as a facet (18) on the other wheel (16). Further, each of the scanning wheels (12, 16) scan in opposite scanning directions. This does not necessarily mean, however, that the wheels are actually rotating in opposite directions. Because both of the scanning wheels (12, 16) are scanning in opposite directions, the scanning of one scanning wheel (16) substantially cancels the scanning of the other scanning wheel (12). Because of the difference in the number of facets (14, 18) between the two scanning wheels (12, 16), the scanning is not entirely cancel out.

Abstract: A method and apparatus which corrects the amplutide variation in the output in an electro-optic modulated laser system (10). Birefringence within the electro-optic crystal (25) causes elliptical polarization of the linearly polarized laser light (22) produced by the laser gain medium (16), in turn causing a loss in the laser output (27). The loss owing to the elliptical polarization is corrected by either applying a D.C. bias from voltage source (30) directly to the electro-optic crystal (25) or by inserting a quarter-wave plate (32) within the laser's resonant cavity.