Abstract: A semiconductor laser or traveling wave intensifier has an active layer between two passive semiconductor layers, and a strip-shaped electrode geometry. The active layer is uniform in thickness, while at least one of the passive layers within the strip-shaped geometry comprises a strip-shaped zone which contains portions having different refractive indices n.sub.1 and n.sub.2. According to the invention it holds that(n.sub.1 -n.sub.2) (d.sub.1 -d.sub.2)>0,wherein n.sub.1 is the refractive index of the portion which at least within said strip-shaped zone adjoins the active layer, d.sub.1 is the thickness thereof within the strip-shaped zone, and d.sub.2 is the thickness thereof beside the strip-shaped zone.

Abstract: An optical modulator is provided in which one light beam is modulated by another. The modulator of the invention includes a saturable medium which is capable of amplifying an optical signal by stimulated emission of radiation. Two optical signals, in the form of two light beams are caused to pass through the medium and to emerge from the medium in amplified form. The beams, however, are caused to have different gains in the medium either by causing the beams to have different path lengths, or by other means. The beams are intercoupled by cross-saturation of the medium. Thus, any variations in the intensity of one of the beams causes a change in intensity in the other beam. Since one of the beams has a greater gain than the other, a small change in the intensity of one of the beams will produce a large change in the intensity of the other beam, thus producing in many aspects the optical analog of the transistor. The modulator of the invention shall be referred to herein as an "opto-optic" modulator.

Abstract: A semiconductor laser/amplifier is disclosed in which the radiation oscillates only in one longitudinal mode. According to the invention this is achieved by a strip-shaped active region which exhibits periodic variations in amplification (and preferably also in the amplification profile) in its longitudinal direction over at least a part of its length. The period of the amplification variation is at least ten times the wavelength of the radiation.

Abstract: Method and apparatus for spreading and angle-encoding each pulse of a multiplicity of small area, short pulses into several temporally staggered pulses by use of appropriate beam splitters, with the optical elements being arranged so that each staggered pulse is contiguous with one or two other such pulses, and the entire sequence of stacked pulses comprising a single, continuous long pulse. The single long pulse is expanded in area, and then doubly passed through a nonstorage laser amplifier such as KrF. After amplification, the physically separated, angle-encoded and temporally staggered pulses are recombined into a single pulse of short duration. This high intensity output beam is well collimated and may be propagated over long distance, or used for irradiating inertial confinement fusion targets.

Abstract: Apparatus is provided which includes a laser oscillator for providing light along a first optical path, and a laser amplifier for amplifying light along a second optical path. Means for coupling light between the first and second optical paths is disposed at one end of the laser amplifier, and a nonlinear medium disposed at the other end thereof for intercepting light provided along the first and second optical paths. The laser oscillator provides a single-mode laser beam along the first optical path which is made incident upon the nonlinear medium from substantially opposite directions. A portion of the beam from the laser oscillator is coupled through the laser amplifier, which forms a probe beam that samples the laser amplifier system. This beam further impinges upon the nonlinear medium and interacts with the counter-propagating laser beams therein.

Abstract: An apparatus and process for pumping a lasing media (preferably krypton fluoride) over a 500 nanosecond period and thereafter compressing and focusing to a target with a final 10 nanosecond compression wave is disclosed. An exciting 10 nanosecond pulse is shaped in an overall rectangular shape with the major axes vertically aligned and this shaped beam directed upwardly and to the side of a normal extending between parallel and opposed mirrors at remote ends of a chamber. The chamber includes at the top thereof a plurality of stripper mirrors aligned along axes substantially normal to the beam path and tilted upwardly to shave successive segments off the upper portion of the beam. Beam passage opposite to the direction of stripper mirror emission produces a series of emitted shaved beam segments each spaced temporally in accordance with stripper mirror separation.

Abstract: A high power metallic halide laser capable of providing 300 watts of output power. More specifically, a laser amplification system is disclosed whereby a metallic halide vapor such as copper chloride (Cu.sub.3 Cl.sub.3) is caused to flow through a laser amplifier (10) and a heat exchanger means (24) in a closed loop system whereby the flow rate is altered to control the temperature rise across the length of the laser amplifier. In the copper chloride laser described in an exemplary embodiment, the copper atoms within the laser amplifier should not exceed a temperature of 3000.degree. K. so that the number of copper atoms in the metastable state will not be high enough to prevent amplification in the amplifier. In addition, a molecular dissociation apparatus (20) is provided at the input to the laser amplifier for dissociating the copper chloride into copper atoms and ions and chlorine atoms and ions.

Abstract: A laser system for generating two closely spaced in time laser pulses where each pulse is a different color comprises a first and second optical cavity with a common optical leg containing a laser rod capable of emitting light of two polarities along an axis and a polarizing beam-splitter positioned at the common junction of the two cavities for splitting the radiation impinging thereon according to polarity and propagating it into the noncommon sections of the first and second optical cavities each of which contains a Q-switch. The output from the cavities is taken at the polarizing beam-splitter and comprises two closely spaced in time pulses of different polarity. The two pulses are applied to a doubler crystal such that pulses of one polarity are doubled while pulses of the other polarity are unchanged.

Abstract: A traveling-wave tube protection circuit prevents faults in its associated power source from damaging it. The power source supplied DC voltages to the collector, slow-wave circuit, anode and cathode of the traveling-wave tube. A power source control circuit is provided between the anode electrode and the anode power source circuit and is used for applying a control voltage to the anode electrode. The control voltage stops the operation of the traveling-wave tube during the transient times which occur responsive to the initiation and the termination of the power source circuit operations. On shutdown, the power source control circuit also stops the supply of the control voltage to the anode electrode after the transient response is terminated. The power source control circuit has a high-frequency oscillator driven in response to either the initiation or the termination of the operation of the power supply means.

Abstract: A line of laser light is produced having a uniform intensity over an area of ten centimeters by one centimeter and having an energy density of several J/cm.sup.2. A grating forms from a laser beam several divergent beams of nearly equal intensity and a converging lens collimates the beams into slightly overlapping paths to produce a uniform line of light in one plane. A laser amplifier in a flat plate configuration in that plane includes a nested series of laser rods of triangular cross-section which are pumped by a plurality of flashlamps to amplify the line of light and produce an intense uniform line of laser light.

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: A cavity formed of Teflon to provide extended static fill lifetimes for gases containing halogens. A double cavity configuration provides structural integrity to the inner Teflon cavity by maintaining an identical multi-atmospheric pressure within the outer structural cavity to minimize tension on the Teflon inner cavity. Use of a quantity of the lasing gas in the outer cavity or a constituent of that gas minimizes contamination of the lasing gas.

Abstract: A coupled cavity traveling wave tube (10, 10') is provided having a velocity taper, i.e., gradual velocity reduction, which affords beam-wave resynchronization and thereby enhances efficiency. The required wave velocity reduction is achieved by reducing the resonant frequencies of the individual resonant cavities as a function of the distance from the electron gun (16, 16'), through changes in internal cavity dimensions. The required changes in cavity dimensions can be accomplished for example, by gradually increasing the cavity radius (R.sub.2, R.sub.3, R.sub.4) or decreasing the gap length (l.sub.1, l.sub.2), from cavity to cavity. With this approach the velocity reduction is carried out without an increase in circuit resistive losses and the upper and lower cut off frequencies are reduced in approximately the same manner.

Abstract: In a traveling wave tube (TWT) with a non-dispersive interaction circuit such as a helix, the length of the circuit in wavelengths, and hence the gain of the tube, varies with the frequency. The variations of gain over a very wide bandwidth can cause oscillation problems. The invention provides an inverse variation with frequency of the physical length over which the circuit interacts with the beam. This is done by resonant attenuators coupling to the interaction circuit over various lengths depending on their resonant frequency, the attenuation being enough to effectively remove the interaction circuit wave. The attenuators are preferably formed of resonant sections of slow-wave circuit deposited on longitudinal ceramic rods such as the helix support rods.

Abstract: A free electron laser system and electron beam system for a free electron laser which use rf feedback to enhance efficiency. Rf energy is extracted from an electron beam by decelerating cavities and returned to accelerating cavities using rf returns such as rf waveguides, rf feedthroughs, etc. This rf energy is added to rf klystron energy to lower the required input energy and thereby enhance energy efficiency of the system.

Abstract: Improved gain and the elimination of beam insertion and extraction compensation in free electron lasers is realized by means of a helical periodic magnet. The magnet comprises one or more layers of coaxial bifilar helical conductors each being 180.degree. displaced and conducting current in opposite directions. The end portions of the magnet are tapered by extending successive layers one or more turns to provide a field gradient that uniformly decreases to zero.

Abstract: In a device for determining the influence of physical parameters on the lth of a path, an elastically stretchable optical fiber is guided with minimal pretensioning along the path which is subjected to length changes. The optical fiber is mounted at least sectionally on supports subjected to positional changes with changes in the length of the path. A transit-time measuring device is also provided as part of the measuring device together with the optical fiber. The transit-time measuring device includes a light-pulse repeater forming a closed signal path with the optical fiber. The repeater generates signal pulses circulating in the signal path with the periodicity of the signal circulation time of the signal path. From an electronically measured total travel time through the closed signal path and a total number of which signal pulses the electrical display signal can then be derived to determine the length and change in length of the path being measured.

Abstract: A high power output CO.sub.2 gas laser amplifier having a number of sections, each comprising a plurality of annular pumping chambers spaced around the circumference of a vacuum chamber containing a cold cathode, gridded electron gun. The electron beam from the electron gun ionizes the gas lasing medium in the sections. An input laser beam is split into a plurality of annular beams, each passing through the sections comprising one pumping chamber.

Abstract: A long pulse laser amplifier is sequentially lased over a 0.5 microsecond period by an additive group of temporarily spaced discrete lasing colors (frequencies) each of slightly different color (approximately 1/10 of an Angstrom separation with less than 1/1000 angstrom band width). An oscillator array generates the actuating pulses which are channelled to common optical path, amplified by a factor of 10.sup.4 and split up and shaped before injection into approximately 10 final amplifiers. Each final amplifier is preceded by a chromatic deflector, preferably a diffraction grating so that each short pulse (in the order of about 10.sup.-8 seconds) is sent through the amplifier at slightly different directions. These differently directed pulses are amplified and individually address a mirror array placed at some distance away. Due to the narrow band width of each pulse, each address point is unique; there is no overlapping.

Abstract: In an injection-locked laser system, a timing system for assuring the locking of an injection-locked oscillator to the frequency of a master oscillator. The system automatically controls the firing of the injection-locked oscillator in accordance with the difference in time between the production of a master oscillator pulse and the time that a predetermined population inversion level has been reached in the injection-locked oscillator as measured by a predetermined level of fluorescence produced by the injection-locked oscillator.

Abstract: Apparatus and method for quickly closing off the return path for an amplified laser pulse at the output of an amplifier so as to prevent damage to amplifiers and other optical components appearing earlier in the chain by the return of an amplified pulse. The apparatus consists of a fast retropulse or post pulse shutter to suppress target reflection and/or beam return. This is accomplished by either quickly placing a solid across the light transmitting aperture of a component in the chain, such as a spatial filter pinhole, or generating and directing a plasma with sufficiently high density across the aperture, so as to, in effect, close the aperture to the returning amplified energy pulse.

Abstract: A regenerative laser apparatus and method using the optical relay concept to maintain high fill factors, to suppress diffraction effects, and to minimize phase distortions in a regenerative amplifier.

Abstract: Generator and power amplifier of plasma confining, electromagnetic, light or infrared wave beam. It comprises a generator of a rectilinear polarized wave beam and a solid state laser beam amplifier amplifying the rectilinear polarized wave beam after conversion of the same and having a doped active material in the shape of an annular sleeve member. This amplifier operates in the TM.sub.o annular mode. It is preceded and followed by mode converters. The first mode converter before the amplifier converts the rectilinear polarized wave beam to a TM.sub.o mode wave beam and the second mode converter after the amplifier converts the amplified TM.sub.o wave beam to a negatively azimuthally phase shifted, circular polarized wave beam.

Abstract: An active mirror laser amplifier is described having a slab of Nd:glass which is optically pumped through the back face while the laser beam enters the slab through the front face and is reflected by a coating on the back face which reflects the laser beam while transmitting the pumping radiation. The laser beam is amplified as it moves toward the back face and after reflection from the back face as it propagates out and is emitted from the front face. The front face has an anti-reflection coating for the laser beam which coating reflects the pumping radiation. The storage efficiency of the laser is thereby increased and the temperature gradients in the slab are reduced (viz., the temperature profile is smoothed such that distortion of the slab is reduced and high power operation at high repetition rates of the laser pulse is obtainable).

Abstract: Linear phase aberrations in laser amplifier systems are adaptively corrected by a device which propagates an object beam formed by reflection of a laser beam from a target backwards through a laser amplifier chain in order to sample the linear phase aberrations and produces a conjugate image beam by degenerate four-wave mixing in a medium having a third order nonlinearity in susceptibility. The conjugate image beam which is amplified as it propagates back through the laser amplifier chain has the linear phase aberrations removed. The device also corrects for birefringent aberrations contained in the laser amplifier chain when (1) the medium has an isotropic nonlinearity; (2) the polarization of the pump beams, required for four-wave mixing, lies in the plane formed by the object beam and the pump beams; and (3) the angle between the object beams and the pump beams is substantially 90 degrees. The degenerate four-wave mixing is accomplished in one embodiment by gain saturation in Nd:YAG.

Abstract: Oscillations due to backward waves in a high-power traveling-wave tube (TWT) are inhibited by a non-reciprocal attenuating device which essentially absorbs only backward waves. A directional coupler mediates the exchange of energy between the TWT interaction circuit and an external circuit containing a non-reciprocal loss element such as a ferrite isolator. In such embodiments the high-frequency power handled by the isolator is much less than the power in the TWT interaction circuit. The frequency band handled by the isolator is much narrower than that handled by the TWT. Coupling to the loss element is through one or more resonant circuit elements such that a "notch" of attenuation is obtained for a backward wave only, at a certain frequency where oscillations are prone, such as the frequency associated with 2.pi. phase shift per cavity in a coalesced-mode coupled-cavity TWT.

Abstract: A plurality of pulsed chemical lasers such as HF or DF lasers are disposed symmetrically about a central axis. Each laser is energized sequentially so that the resulting output laser pulses have substantially consecutive time duration. Hence, the duration of the laser pulses equals the duration of each laser times the number of lasers. Reflectors are provided for combining the output pulses of each laser to generate a segmented output beam.

Abstract: A laser secure communications system is disclosed. The system utilizes a long laser cavity, the end reflecting members of which may be located many kilometers apart. One or more high gain laser amplifiers optically aligned within the long laser cavity provide the optical carrier energy. Laser oscillation only occurs if the remotely located end reflectors are optically aligned and if the laser gain is sufficient to overcome the round trip transmission loss. The optical carrier thus established is modulated and detected at either end of the laser cavity.

Abstract: Crossed field amplifier collector efficiency is improved by decreasing the ratio of electron velocities to r.f. signal wave velocity at the output end of the amplifier slow wave circuit. In a preferred embodiment of the invention this is accomplished by tapering the sole emitting cathode so as to increase the cathode-slow wave circuit spacing in the output end of the interaction region prior to the collector. Alternatively, an increasing r.f. signal phase velocity taper can be used to provide the required decreased electron velocities to r.f. signal wave velocity ratio.

Abstract: A laser oscillator output pulse is separated into a plurality of separate beams which are temporally or spatially individually amplified by a power amplifier. The beams may then be recombined to provide a more powerful output than conventional single beam amplification.

Abstract: A nonlinear interferometer apparatus is disclosed wherein a Fabry-Perot cavity is substantially filled with an electro-optic material having terminals to which a potential can be applied. A single frequency, single mode, linearly polarized source of optical radiation is coupled into the cavity and a beam splitter at the output of the cavity deflects a portion of the optical energy coming from the cavity. This deflected portion of output optical energy is incident on a photodetector whose output is amplified and connected to the terminals of the electro-optic material. The resulting device exhibits differential gain, and can function as an optical switch, limiter or optical memory element. With sufficient amplification of the detector output, an optical quantizer is provided.

Abstract: A semiconductor device includes a semiconductor layer on one side of a semiconductor body to define a pn-junction therebetween, diffraction gratings formed at a distance from each other on the top of said semiconductor layer, and electrodes formed between the diffraction gratings on the top of said semiconductor and formed on the other side of the semiconductor body.

Abstract: In addition to the apparatus disclosed in the prior patent applications of which this application is a continuation-in-part, a reaction chamber is provided with mercury vapor quartz discharge lamps. In close proximity to the lamps are spheres, or thin continuous wires, or filaments or other physical configurations of laser-type material which produce relatively coherentradiation in a manner similar to lasers. The spheres or filaments include concentric partially reflective surfaces, and include an active material which is pumped by the efficient spectral radiation of the mercury vapor, and radiates at a frequency or frequencies matched to the absorption characteristics of the feedstock being fed through the reaction chamber.

Abstract: High energy laser system using a regenerative amplifier, which relaxes all constraints on laser components other than the intrinsic damage level of matter, so as to enable use of available laser system components. This can be accomplished by use of segmented components, spatial filters, at least one amplifier using solid state or gaseous media, and separated reflector members providing a long round trip time through the regenerative cavity, thereby allowing slower switching and adequate time to clear the spatial filters, etc. The laser system simplifies component requirements and reduces component cost while providing high energy output.

Abstract: A laser amplification system comprises in series on the emission axis of a laser oscillator a germanium plate inclined at the Brewster angle, a Fresnel parallelepiped, a laser amplifier and a reflecting mirror, as well as a Fresnel parallelepiped and a laser amplifier aligned on the reflection axis of the plate. The system is intended for application in the study of plasmas.

Abstract: A solid state laser including a plurality of plate like lasable elements in an array on a common optical axis. There are two different plate like elements, arranged in an alternating pattern, each containing a lasing ion which lases at a wavelength that is different from the wavelength of the other. The lasing ions and host materials are chosen so that there are two distinct spectral regions in which the lasing output of one plate element is not strongly absorbed by the other plate element.

Abstract: A laser system employs a laser amplifier doped with Neodymium ions having a planar input surface receiving a laser beam having a wavelength of 1.06 microns from a laser generator also employing a Neodymium doped crystal. The laser amplifier provides an output face axially aligned with the input face and having a diameter of approximately one-fifth of the input face diameter. Approximately eighty-eight percent of the axial length of the amplifier crystal is tapered to provide a continuously decreasing cross-section from a point near the input face to a point near the output face and forming a tapered spontaneous pumping zone of substantially reduced diameter adjacent the output face. A special retainer encloses the laser amplifier which directs output pulses from the output face through a bronchoscope to vaporize carbon and possibly other particles located on alveoli within a lung of a living mammal.

Abstract: An energy level due to isoelectronic impurity is provided in the forbidden band of one portion of an optical waveguide in a semiconductor material by doping said portion with an isoelectronic impurity. Upon excitation, a population inversion of electrons and holes is produced in the energy level and the valence band of said portion. When a light having a wavelength corresponding to the energy difference between the level of the isoelectronic impurity and the valence band is impinged on the portion, the incident light is amplified thereby. Since the optical energy of the output is smaller than the forbidden band gap, the attenuation in the waveguide is very small.

Abstract: A direct nuclear radiation pumped laser consisting essentially of a uranyl salt with a UO.sub.2.sup.++ uranyl ion enriched in the U.sup.235 isotope sufficient to sustain a fission chain reaction, the uranyl ion being directly nuclear radiation pumped by a fission power transient of the core to produce laser action between a low-lying vibrational level of the first triplet electronic state and an upper vibrational level of the singlet ground state.

Abstract: To suppress spurious oscillations in a helix-type traveling wave tube (TWT), frequency-sensitive loading is produced by a lossy resonant circuit attached to a dielectric support and coupled to the fields of the interaction circuit. The lossy circuit is resonant near the band-edge frequency. It may be a section of delay line with reflective terminations. In one embodiment, it is a metallized pattern on a dielectric rod used to support the helix.

Abstract: A delay line for transit time amplifier tubes which has a filter characteristic with a negative dispersion in the fundamental wave of the longest pass band, i.e.

Abstract: A system consisting of a set of spatial filters that are used to optically relay a laser beam from one position to a downstream position with minimal nonlinear phase distortion and beam intensity variation. The use of the device will result in a reduction of deleterious beam self-focusing and produce a significant increase in neutron yield from the implosion of targets caused by their irradiation with multi-beam glass laser systems.

Abstract: This invention discloses two classes of optical configurations for high power laser amplification, one allowing near-field and the other allowing far-field optical separation, for the multiple passage of laser pulses through one or more amplifiers over an open optical path. These configurations may reimage the amplifier or any other part of the cavity on itself so as to suppress laser beam intensity ripples that arise from diffraction and/or non-linear effects. The optical cavities combine the features of multiple passes, spatial filtering and optical reimaging and allow sufficient time for laser gain recovery.

Abstract: An amplifier system for high power lasers, the system comprising a compact array of segments which (1) preserves high, large signal gain with improved pumping efficiency and (2) allows the total amplifier length to be shortened by as much as one order of magnitude. The system uses a three dimensional array of segments, with the plane of each segment being oriented at substantially the amplifier medium Brewster angle relative to the incident laser beam and with one or more linear arrays of flashlamps positioned between adjacent rows of amplifier segments, with the plane of the linear array of flashlamps being substantially parallel to the beam propagation direction.

Abstract: A device is disclosed for amplifying electromagnetic waves propagating al a meander line slow wave structure by means of magnetic cylindrical domains or bubbles which are propagating at substantially the same velocity as the RF wave in an adjacent platelet of orthoferrite having associated with it a propagation arrangement of the conventional type which is adapted to move the domains from one end of the platelet to the other. Since the magnetic bubbles are magnetic dipoles that produce magnetic surface charges, a portion of their energy is transferred to the propagating RF wave, resulting in amplification of the RF wave.

Abstract: The cut-out device comprises a saturable absorbing medium and a monochromatic filter disposed between two amplifying media in the path of laser light pulses. The cut-out device forestalls amplification of light spontaneously emitting in one amplification medium by the following amplification medium, thereby reducing energy losses from pumped amplifying media prior to the passage of a laser pulse.

Abstract: In a multi-section laser amplifier, the amount of amplification available for a given number of sections is increased by passing a polarized beam of light through the initial sections of the laser amplifier twice, in opposite directions, and preventing its re-emergence at its initial point of entry by polarization discriminating means.

Abstract: A band-rejection filter which rejects harmonic components of the fundamental frequency of the output of a helix type travelling-wave tube is built into the connection of the output connection from the tube to its external circuit. A wide variety of specific filter structures are disclosed.

Abstract: The invention concerns a travelling wave laser and has application to the reduction of the divergence of laser beams. The electrodes between which the travelling electric discharge for the excitation of the amplifier gas takes place have a cross-section in the shape of two polished rounded-off points facing each other, so as to prevent spurious reflections of light towards the discharge zone and to reduce the divergence of the output beam which is converged by means of a simple optical system.

Abstract: An infrared laser system and method for isotope separation may comprise a molecular gas laser oscillator to produce a laser beam at a first wavelength, Raman spin flip means for shifting the laser to a second wavelength, a molecular gas laser amplifier to amplify said second wavelength laser beam to high power, and optical means for directing the second wavelength, high power laser beam against a desired isotope for selective excitation thereof in a mixture with other isotopes. The optical means may include a medium which shifts the second wavelength high power laser beam to a third wavelength, high power laser beam at a wavelength coincidental with a corresponding vibrational state of said isotope and which is different from vibrational states of other isotopes in the gas mixture.