Abstract: An active optical fiber for use in an amplifier or laser has an inner cladding and an outer cladding. An index grating is written into the inner cladding to provide coupling between cladding modes of pumping radiation conducted in the inner cladding. The periodicity of the index grating is selected to couple energy from cladding modes having minimal overlap with the core to cladding modes having relatively high overlap. The efficiency of pumping the radiation amplifying medium of the core is thereby improved. The fibre has utility in transmitters for broad band networks.

Abstract: A line narrowing system in which a polarizing beam splitter, a polarization rotator and a reflecting optic are configured to cause light in an expanded beam from a laser gain medium to illuminate a grating at least twice in each pass through the line narrowing system before returning to the gain medium for further amplification. In a preferred embodiment, the grating is an echelle grating arranged in a Littrow configuration.

Abstract: The present invention provides a Yb-doped crystal for a solid state laser, wherein a main active element of the Yb-doped crystal comprises Yb.sup.3 +. The Yb-doped crystal for a solid state laser is prepared by increasing a ratio of Yb.sup.3 + to Yb.sup.2 + in a Yb-doped material by a heat treatment to the Yb-doped material in an oxidizing atmosphere, and carrying out a crystal growth of the Yb-doped material.

Abstract: A high voltage pulse power generating circuit capable of eliminating secondary pulses due to stage mismatch in the stages of its magnetic pulse compressor circuit is disclosed. The pulse generating circuit source comprises a high voltage charge storing element which is periodically discharged into a nonlinear magnetic compressor circuit. A mismatch correction circuit coupled to each stage of the compressor circuit discharges the reflected energy due to stage mismatch and thus eliminates the reflected energy from being launched back into the load. In a preferred embodiment, the pulse power generating circuit of the present invention utilizes a diode and a resistor that is coupled to each stage of the magnetic pulse compressor circuit. Various embodiments are disclosed.

Abstract: Laser diode pumped mid-IR wavelength systems include at least one high power, near-IR wavelength, injection and/or sources wherein one or both of such sources may be tunable providing a pump wave output beam to a quasi-phase matched (QPM) nonlinear frequency mixing (NFM) device. The NFM device may be a difference frequency mixing (DFM) device or an optical parametric oscillation (OPO) device. Wavelength tuning of at least one of the sources advantageously provides the ability for optimizing pump or injection wavelengths to match the QPM properties of the NFM device enabling a broad range of mid-IR wavelength selectivity. Also, pump powers are gain enhanced by the addition of a rare earth amplifier or oscillator, or a Raman/Brillouin amplifier or oscillator between the high power source and the NFM device. Further, polarization conversion using Raman or Brillouin wavelength shifting is provided to optimize frequency conversion efficiency in the NFM device.

Abstract: A laser beam generator includes first and second mirrors, a laser light source, a laser medium, a non-linear optical crystal element and a birefringent element. The laser light source generates a pumping light beam. The laser medium, arranged between the first and second mirrors, is irradiated with the pumping light beam via one of the mirrors to generate a fundamental laser beam based on the pumping light beam. The non-linear optical crystal element is arranged between the first and second mirrors to generate a second harmonic laser beam under the type II phase matching as the fundamental laser beam from the laser medium is passed through it in resonant oscillation. The birefringent element has its one surface at a pumping light beam inlet side coated with a high reflectance coating and has its opposite surface parallel to it with a nonreflective coating.

Abstract: A nozzle for mixing of two reacting fluids wherein the first reactant, flowing across the nozzle, exhibits a variation in reactivity towards the second fluid, introduced through the nozzle and mixing and reacting with the first fluid within the nozzle, and wherein the nozzle is configured to permit this second fluid to be introduced in a way as to compensate for the variation in reactivity and to produce uniform reactant mixture from the two fluids.

Abstract: A surgical laser system is provided with improvements to allow it to operate at higher power levels without beam divergence. The improvements include a beam expansion telescope in the optical path of the beam and modifications to the optical cavity and the lasing medium. The modifications include imposing a negative curvature on one or both ends of the rod, configuring the optical cavity as a positive-branch unstable resonator, and providing at least one intra-cavity shutter.

Abstract: A DFB laser is provided with a top electrode divided symmetrically into two or three in-line separate elements through which a bias current is applied with a symmetrical distribution and through which a modulation current is applied in push-pull with a temporal asymmetry.

Abstract: A laser structure for obtaining an optical pulse of a very short duration by using the benefit of a passive mode locking and for improving a repetition rate of an output optical pulse was described. In general, a passively mode-locked laser generates a short optical pulse than a active mode locked laser does, while it has difficulties in increasing the repetition rate of the output optical pulse because the repetition rate of the passively mode-locked laser is determined by the length of the resonator. In accordance with the present invention, a delayed optical path is added to the linear loop of a conventional figure-8 optical fiber laser. The propagation time difference .DELTA.T between the delayed optical path and undelayed short optical path is adjusted to a divisor of the round trip time, T, of the original resonator by properly adjusting the length of the delayed optical path. Thus, the repetition rate of the output optical pulse of the mode locked laser can be increased from 1/T Hz to 1/.DELTA.T Hz.

Abstract: Third harmonic generated from intra-cavity frequency tripled resonator is disclosed in which type II phase matching crystal is used as the tripler. Type I phase matching is used for second harmonic generation. The resonator efficiently converts the fundamental laser frequency to its third harmonic laser beam. The laser is highly efficient with high third harmonic output stability. Overall conversion efficiency exceeds 25% and preferably is 50% or higher.

Abstract: A gas laser apparatus for generating a laser beam along a light beam axis, comprises, a gas as a laser medium, a dielectric tube through which the gas passes, and which surrounds the light beam axis, a pumping source generating an electric discharge through the gas existing in the dielectric tube to excite the gas so that a laser light is generated from the excited gas, and a gas blower blowing the gas into the dielectric tube, wherein the gas blower forms a circumferential flow direction component of the gas in the dielectric tube.

Abstract: This invention relates to a metal vapor laser device comprising a sealed enclosure, electrodes placed inside this enclosure, a reactant metal or metal alloy placed between the electrodes, and an elongated pipe or tube to introduce reactive gas between the two electrodes.

Abstract: A laser includes a split-wave hybrid resonator that produces a high quality laser beam from a low gain laser medium. The split-wave hybrid resonator includes a resonator cavity formed by a pair of resonator mirror surfaces positioned at opposite ends of the laser medium and a pair of resonator walls positioned on opposite sides of the resonator cavity. The resonator walls are separated from each other by a separation distance such that the resonator cavity has a Fresnel number between approximately 0.5 and 1.5. At least one of the resonator walls includes a first ring oscillation filter adjacent to the lasing medium to filter out ring oscillations within the laser medium. One or more of the resonator walls may include first and second wall portions angled with respect to each other to form a wave-front splitting interferometer. The resonator mirrors are tilted off-axis with respect to the resonator walls.

Abstract: A continuous wave photolytic iodine laser has a gain cell for receiving a continuous supply of gaseous fuel. The gain cell is connected to laser beam transfer optics, a laser resonator for shaping a laser beam, and a lamp. The lamp is driven by a microwave subsystem such that a laser gain medium is pumped through the gain cell. The continuous wave photolytic iodine laser of the present invention incorporates a closed loop fuel system for presenting gaseous fuel to the gain cell at a rate sufficient to sweep any lasing by-products out of the gain cell, thereby preventing quenching of the lasing process. The fuel system also includes a condenser for converting the gaseous fuel to a liquid after it has passed through the gain cell, a scrubber for removing the by-products of the lasing process from the fuel, and an evaporator for converting the recycled liquefied fuel back to a gas. The closed loop fuel system also includes a pump for pressurizing and transporting the liquefied fuel.

Abstract: A confocal optical scanning system using a flexible optical emissive fiber or fiber laser and having a lasing cavity defined within the fiber. The system in-couples a signal beam produced when a probe beam generated by the fiber laser is reflected from a scanned object back into the lasing cavity. The perturbation created in the cavity by the in-coupling of the signal beam is detected by a transducer. Specifically, the perturbation may be the signal beam itself, an oscillation mode of the cavity induced by the in-coupled signal beam or a combination of the signal beam and the probe beam. In a preferred embodiment of the invention the system also has a polarizing assembly for altering a signal polarization of the signal beam and rotate it to either a resonant polarization supported by the cavity or a non-resonant polarization not supported by the cavity.

Abstract: A process for selecting an operating range for a narrow band KrF or ArF excimer laser. The laser is operated at a desired pulse energy until the fluorine concentration has depleted sufficiently so that the charging voltage needed for the desired pulse energy is at or near a predetermined maximum range. The average charging voltage, the average line width, and the average energy sigma are recorded; and the fluorine concentration is estimated or determined. A quantity of fluorine, at least sufficient to cause a measurable decrease in the charging voltage needed to produce the desired pulse energy, is injected; and another set of data is recorded. Another similar quantity of fluorine is injected, and another set of data is recorded. These two steps are repeated until the voltage is at or near a predetermined minimum voltage range. The recorded data are used to select an optional operating range. The data may be plotted to make the selection easier.

Abstract: A longitudinally pumped laser including a pumping module having a pumped light source and an input optic, and a resonator having a first reflecting surface serving as an input mirror, a laser medium and a second reflecting surface serving as an output mirror. In order to avoid impairment of the operation of the pumped light source by retroreflected pumped light and/or by leakage radiation from the resonator, without appreciably worsening the adaptation of the pumped light ray to the mode volume of the laser, the pumping module and the resonator are so disposed relative to each other that a first optical axis defined by the pumped light source and input optic defines with a second optical axis defined by the resonator a predetermined angle of intersection greater than 0.degree. and less than about 15.degree., and more preferably in the range of about 0.05.degree. and about 1.degree..

Abstract: An extruded aluminum gas laser tube assembly (10) has a pair of extruded, elongated, electrically insulated, aluminum electrodes (23,24) adapted to couple to an external RF supply and supported in the laser tube in predetermined spaced-apart relationship relative to each other and to the laser tube (11). The electrode supporting structure is eight pairs of matching, longitudinal, machined grooves (12,21), four pairs at each end of the tube (11) and electrodes (23,24) in each of which pairs is received a cylindrical, insulated, anodized aluminum spacer pin (22) which slidably supports the electrodes in the tube and allows longitudinal expansion of the electrodes relative to the tube substantially without bending.

Abstract: In a pulsed Fabry-Perot laser, such as a Q-switched laser or a mode-locked laser, one of the resonator reflectors comprises a waveguide loop coupled to the gain medium via a circulator. In one embodiment, only a modulator is located in the loop. In another embodiment, the circulator is switchable and the loop may contain either an unidirectional device, such as an isolator, or may contain only the waveguide itself, depending on which states of the circulator are utilized in the switching process. Also described are several arrangements for multiplexing lasers of different operating wavelengths.