Abstract: Co-doping the gain medium of a diode-pumped infrared laser to make the laser resistant to long-term degradation from high-intensity internal infrared radiation is disclosed. Co-doping the gain medium with ions such as Cr3+ and Ce3+ that make the gain medium resistant to external ionizing radiation solves problems of long-term degradation of the gain medium.

Abstract: Co-doping the gain medium of a diode-pumped infrared laser to make the laser resistant to long-term degradation from high-intensity internal infrared radiation is disclosed. Co-doping the gain medium with ions such as Cr3+ and Ce3+ that make the gain medium resistant to external ionizing radiation solves problems of long-term degradation of the gain medium.

Abstract: An optical fourth-harmonic generation system includes a resonant cavity configured to support electromagnetic radiation of a fundamental frequency and a fourth-harmonic generator disposed within the resonant cavity produces electromagnetic radiation of a fourth-harmonic frequency by an interaction with radiation of the fundamental frequency. The fundamental radiation is characterized by a p polarization that is complementary to an s polarization that characterizes the fourth-harmonic radiation. The fourth-harmonic generator has an output facet oriented substantially at a Brewster's angle with respect to the fundamental radiation to separate the fundamental radiation from the fourth-harmonic radiation as they emerge from the output facet.

Abstract: An optical fourth-harmonic generation system includes a resonant cavity configured to support electromagnetic radiation of a fundamental frequency and a fourth-harmonic generator disposed within the resonant cavity produces electromagnetic radiation of a fourth-harmonic frequency by an interaction with radiation of the fundamental frequency. The fundamental radiation is characterized by a p polarization that is complementary to an s polarization that characterizes the fourth-harmonic radiation. The fourth-harmonic generator has an output facet oriented substantially at a Brewster's angle with respect to the fundamental radiation to separate the fundamental radiation from the fourth-harmonic radiation as they emerge from the output facet.

Abstract: A third-harmonic crystal has a Brewster-cut dispersive output surface for separating the p-polarized fundamental and third-harmonic beams without introducing losses into the beams. The output surface of the third-harmonic crystal is optically uncoated, and thus insensitive to potential ultraviolet (UV)-induced damage. Frequency doubling and tripling lithium triborate (LBO) crystals are used with a Brewster-cut Nd-YAG active medium in a resonant cavity to generate UV light at 355 nm from infrared (IR) light at 1064 nm. Except for the tripling crystal output surface, the doubling and tripling crystal optical surfaces are normal-cut and anti-reflection (AR) coated.

Abstract: A multiple-pass laser amplifier that uses optical focusing between subsequent passes through a single gain medium so that a reproducibly stable beam size is achieved within the gain region. A confocal resonator or White Cell resonator is provided, including two or three curvilinearly shaped mirrors facing each other along a resonator axis and an optical gain medium positioned on the resonator axis between the mirrors (confocal resonator) or adjacent to one of the mirrors (White Cell). In a first embodiment, two mirrors, which may include adjacent lenses, are configured so that a light beam passing through the gain medium and incident on the first mirror is reflected by that mirror toward the second mirror in a direction approximately parallel to the resonator axis. A light beam translator, such as an optical flat of transparent material, is positioned to translate this light beam by a controllable amount toward or away from the resonator axis for each pass of the light beam through the translator.

Abstract: A multiple-pass laser amplifier that uses optical focusing between subsequent passes through a single gain medium so that a reproducibly stable beam size is achieved within the gain region. A resonator or a White Cell cavity is provided, including two or more mirrors (planar or curvilinearly shaped) facing each other along a resonator axis and an optical gain medium positioned on a resonator axis between the mirrors or adjacent to one of the mirrors. In a first embodiment, two curvilinear mirrors, which may include adjacent lenses, are configured so that a light beam passing through the gain medium and incident on the first mirror is reflected by that mirror toward the second mirror in a direction approximately parallel to the resonator axis. A light beam translator, such as an optical flat of transparent material, is positioned to translate this light beam by a controllable amount toward or away from the resonator axis for each pass of the light beam through the translator.

Abstract: Method and apparatus for stabilization of pulse energies produced by a continuously pumped, Q-switched, solid-state or gas laser, through control of the optical power delivered by an optical pump to the laser, in order to limit the energy emitted in any single laser pulse as a result of Q-switching. The laser pump is driven at full strength for a selected initial refresh time t.sub.r. If a Q-switch trigger signal is received by the laser before the elapsed time .DELTA.t has reached the refresh time t.sub.r, the laser emits a pulse with the reduced energy stored in the laser at that time. If the elapsed time reaches or exceeds the refresh time t.sub.r, the optical pump power subsequently delivered to the laser is reduced to a lower level, which may be time-dependent, that is sufficient to maintain the net energy stored in the laser at a predetermined value so that the energy in a subsequently emitted laser pulse does not exceed a selected limit.

Abstract: A miniature laser cavity in which a solid-state lasing gain element and a Q-switch have respective end surfaces at substantially the Brewster angle, parallel to and facing each other, and separated by a narrow gap occupied by a transparent low-index-of-refraction material.

Abstract: A diode imaging system using a single objective lens and a single cylindrical lens. This imaging system does not image perfectly point-to-point, and although not an apparent extension of imaging systems known in the prior art, it works advantageously for imaging beams from diode lasers having long narrow junctions used in pumping solid-state lasers.

Abstract: An optical Faraday isolator includes a slab of Faraday rotator medium coated to define input and output faces and internal reflective surfaces for causing the beam to travel between the input and output faces along a zig-zag path. Permanent magnets polarized in a direction normal to the plane defined by the zig-zag beam path are disposed on opposite sides of the beam path. The magnets are paired on each side with serially alternating polarity and the like poles are in transverse registration on opposite sides of the beam path to produce an intense, unidirectional magnetic field parallel to the beam path within the rotator slab. A quarterwave plate introduces a compensating amount of elliptical polarization to cancel unwanted elliptical polarization effects of the slab and its coatings. A beam shaving aperture at the exit of the slab shaves off divergent backward travelling rays.

Abstract: An encoder for providing a conical array of temporally phased pulse beams. A pulse is inserted and continuously recirculated around an optical ring. The pulse is amplified during each circulation and a portion of the pulse is emitted at the end of each circulation. The encoder includes means for spatially separating each emitted pulse to provide a conical array of beams at a constant field angle relative to the optical axis of propagation.