Abstract: An optical system transmits a first radiation beam along a first axis and receives a reflected beam along that axis; the first beam having a first wavelength and a p-planar polarization; the second beam having the first wavelength, a p-planar polarized component, an s-planar polarized component, and a greater cross-sectional area than the first beam. The system includes a transmit/reflect mirror positioned at a 45.degree. to the first axis and free of apertures in its optical area, a radiation source, an element for directing radiation from the source along the first axis toward the mirror; an element for directing radiation outwardly from the mirror along the first axis, and for directing the second beam along the first axis toward the mirror. An antireflection coating on the primary side of the mirror passes radiation having the first wavelength and a p-planar polarization.

Abstract: A laser system is described in which two laser elements are configured as an oscillator and an amplifier in a common optical pumping section. Oscillator element is in a resonator and a divergent oscillator output beam is steered by a steering arrangement back to the amplifier element. The divergence of the beam from the resonator is adjusted, by moving output coupler element or selecting particular curvatures of resonator mirrors for example, to match the thermal lensing power of the amplifier element so that a substantially collimated output beam is produced.

Abstract: Cladding-pumped fibers are used for chirped pulse amplification of ultrashort optical pulses, increasing the average output power by one order of magnitude and substantially decreasing the cost of pump sources. Broad-area multimode diode pumped Er/Yb codoped fiber amplifiers and MOPA pumped high-power Er-doped fiber amplifiers are used to achieve chirped pulse amplification.

Abstract: The fiber optic laser system and associated lasing method amplifies and divides a primary laser signal into a plurality of secondary laser signals. The fiber optic laser system includes a distribution means, such as a distribution module, for dividing a primary laser signal, generated by a master oscillator into a number of secondary laser signals. The distribution module can include amplification means, such as an optical fiber amplifier, for amplifying the primary laser signal and a signal power splitter for dividing the amplified primary laser signal into a number of secondary laser signals. The secondary laser signals can then be further amplified, such as by a power amplification module including another optical fiber amplifier. The secondary laser signals can be recombined to produce a laser output having a power level greater than the predetermined power level of the primary laser signal.

Abstract: An epitaxial structure suitable for use in a light-emitting device having at least one operating frequency in the visible range, and a method for providing the same. The epitaxial structure includes a semiconductor substrate which is transparent at the operating frequency, an output mirror lattice-matched to the substrate and comprising at least one pair of semiconductor layers having substantially different refractive indices and an active region lattice-matched to the substrate and having a bandgap narrower than the bandgap of the output mirror.

Abstract: A waveguide laser (10) incorporates a guide (12) and two concave resonator mirrors (14, 16). The guide (12) is of square section with side (2a), and of length L equal to 4a.sup.2 /.lambda., where .lambda. is a laser operating wavelength. The mirrors (14, 16) are phase matched to respective Gaussian intensity profile radiation beams with beam waists at respective waveguide end apertures (20, 22). Each beam waist has a radius w.sub.0 in the range 0.1a to 0.65a to avoid waveguide edge effects and excitation of unwanted high order waveguide modes. The laser (10) has good transverse spatial mode characteristics.

Abstract: A tunable source of narrowband coherent radiation comprises a pulsed pump laser (10), an optical parametric oscillator or amplifier (12) and a so-called master oscillator (14). The narrowband output radiation of the master oscillator serves as seed radiation which is injected into the optical parametric oscillator or amplifier (12). In order to obtain a beam profile of the emitted output radiation as homogeneous as possible, optically imaging elements (28) are arranged in an optical delay line (24) for the partial pulses which pump the optical parametric oscillator or amplifier, which transform the spatial beam profile at the output (30) of the pump laser (10) with respect to amplitude, phase and, preferably, the divergence, too, into the crystal of the optical parametric oscillator or amplifier.

Abstract: A mirror mount assembly has a base plate positioned at one end of a laser resonator, and a movable plate spaced from and positioned substantially parallel to the base plate. One or more elastic springs are connected between the base plate and the moveable plate to provide tip and tilt of the movable plate and translation of the moveable plate away from or towards the base plate. The elastic springs include a bushing made of an elastic material, and at least three elastic dimples formed in the bushing circumferentially in a plane across a bushing longitudinal axis. Further, the elastic spring has a bushing made of an elastic material capable of elastic expansion and contraction. The bushing includes a threaded interior side and a longitudinal axis from a first open end of the bushing to a second open end of the bushing.

Abstract: In a solid state laser, a solid state laser medium is pumped with a pumping source. A wavelength selector element is disposed in a laser resonator and a twisting element makes a mode of an oscillating beam a twisted mode in the laser resonator.

Abstract: A tunable narrowband source of a coherent radiation, comprisinga first optical parametric oscillator (OPO1) which includes at least one first optical parametric amplifier medium (K.sub.1) in a resonator (18, 20; 20, 34) or an optical parametric generator;at least one second optical parametric oscillator (OPO2) which includes at least one second optical parametric amplifier medium (K.sub.

Abstract: There is provided a device for monitoring the light output of a VCSEL and a recording and reproducing optical pick-up adopting the device. The device for monitoring the light output of a VCSEL has a half mirror positioned in front of a VCSEL, for reflecting a portion of the light emitted from the VCSEL, and a monitoring optical detector positioned behind the VCSEL, for detecting the light reflected from the half mirror. The recording and reproducing optical pick-up employing the device includes a VCSEL having a light-emitting surface for emitting light vertically from the light-emitting surface, a light output monitor for monitoring the light output of the VCSEL, an objective lens for concentrating incident light on an optical recording medium to form an optical spot thereon, a light path changer for changing a path of the light reflected from the optical recording medium, and a first optical detector for receiving the reflected light and detecting an error signal and an information signal.

Abstract: A semiconductor laser device that is modular can readily be changed to produce laser configurations for a broad spectrum of applications, using a minimum of components. A set of semiconductor modules covering wavelengths and polarizations of interest in specific technologies can be coupled to one of two beam shaping modules and projected through a selected objective optics module to provide large and small circular beams as well as broad and narrow line segments. Resolution enhancing and diffraction limiting filters may be included in the objective optics.

Abstract: A laser apparatus comprises a plurality of laser beam sources for radiating out a plurality of laser beams such that the laser beams may intersect one another on a predetermined virtual plane, through which the laser beams pass. A Fourier transform lens array optical system, which divides the laser beams having impinged upon the virtual plane into small regions and carries out Fourier transform of the small regions, is located in the vicinity of the virtual plane. A laser resonator mirror optical system is constituted of a first laser resonator mirror, which is located at a position that receives the laser beams having been radiated out of the Fourier transform lens array optical system, and a second laser resonator mirror, which is located at a position rearward from the laser beam sources. The laser apparatus coherently combines the later beams with one another without reducing the radiant energy combining efficiency and thereby radiates out a combined laser beam having a high output power.

Abstract: A device for extending the duration of a light pulse by a factor of an integer or by a factor which differs from an integer. The light pulse is passed through a device which divides the initial beam into a number of parts, where the first part passes unhindered while the subsequent parts of the beam are retarded and pass through the system after various delay periods, resulting in the desired extension of the pulse duration. The basic components of the novel device are spherical mirrors facing each other, a special reflector and a translation plate.

Abstract: A solid-state lasers and method of operating the laser is described having a microwave-driven (MWD) visible excimer fluorescence source for exciting a solid-state laser. The laser of this invention provides an efficient, compact, and tunable solid-state laser preferably for use with tunable vibronic laser crystals. Further described is an excimer lamp that has the capability of provided illumination at varying wavelengths. In one embodiment an excimer is selected in a desire to maximize light absorption in plants. This is accomplished by tuning the lamp to provide an output compatible with plant chlorophyll.

Abstract: In an optical fiber light source a section of multimode fiber is interposed between an energizing laser (e.g,, a diode laser) and a single mode fiber active medium. In a preferred embodiment the single mode fiber active medium is surrounded by a multimode cladding coupled to the multimode fiber. The source may serve as a pump laser for a fiber amplifier or as an amplified spontaneous emission source. Arrangements for coupling several energizing lasers to the active medium are also described.

Abstract: A single longitudinal mode Nd:YAG laser oscillates in the range around 0.9 .mu.m and its oscillation mode is brought to a single longitudinal mode by an etalon disposed in a resonator. The thickness, reflectivity and inclination of the etalon and the separation of the resonator longitudinal modes are adjusted to meet conditions,0.6%.ltoreq.R.sub.N .ltoreq.3%, 0.2.degree..ltoreq..theta..ltoreq.1.degree.wherein R.sub.N represents the effective reflectivity of the etalon at a wavelength .lambda.=.lambda..sub.0 .+-..DELTA..lambda.c deviated from the resonance wavelength .lambda..sub.0 of the etalon by the separation .DELTA..lambda.c of the resonator longitudinal modes and .theta. represents the inclination of the optical axis of the etalon to the optical axis of the resonator.

Abstract: In an optical wavelength converting apparatus, a fundamental wave impinges upon a crystal of a nonlinear optical material, the type II of phase matching between the fundamental wave and its second harmonic is effected, and the second harmonic of the fundamental wave is thereby radiated out of the optical wavelength converting apparatus. Two crystals constituted of the same material are employed as the crystal. The two crystals have equal lengths and are located in orientations such that corresponding optic axes may be shifted 90.degree. from each other. The optical wavelength converting apparatus yields the second harmonic having the maximum possible output power and yet can be kept small in size and low in cost.

Abstract: A monolithic solid state laser structure is used to construct erbium lasers that are insensitive to external pressure changes and vibrations, and have improved cooling of the gain medium and reduced thermal lensing effect. In the monolithic laser structure, the gain medium is separated from an optically transmissive plate on one side and a wave plate on the other side by spacers to form narrow air gaps which provide effective cooling of the gain medium and reduced the thermal lensing effect. Such an arrangement is further combined with a pressure-insensitive Brewster polarizer, such as a solid Brewster polarizer or a pressure-sealed Brewster plate, to form a pressure-insensitive laser cavity. The wave plate cooperates with the Brewster polarizer to select the wavelength of the solid state laser.

Abstract: An excitation system for a gas laser featuring a multiplicity of gain channels uses a resonant cavity to provide broad band RF power division and impedance matching to the multiplicity of gain channels. Integral anode and grid resonant tank circuits featuring positive feedback may be employed to provide a self-excited power oscillator having a very high power capability with good efficiency at low cost. A smaller and higher frequency multi-channel excitation system fabricated from stripline resonator elements may be used for driving small scale multi-channel lasers. A common optical extraction system features either a stable, an unstable, or a hybrid optical cavity mode, with phase-locked or non-phase locked output performance, achieved via external or self-injection.

Abstract: The present invention is a beam scanner for use about a nonlinear optical crystal for frequency conversion. The scanner oscillates the high power laser beam passing through the crystal to reduce heat damage and does not change the direction or the position of the beam upon exiting the scanner. A pair of thick optical plates are affixed to a driven axle being parallel to the laser beam direction. The first plate is mounted at a given angle to the axle and the second plate is mounted at the same but negative angle to the axle so that they are mirror images about the crystal. As the axle rotates, the laser beam moves through the crystal in a cylindrical pattern and due to the manner of mounting the plates, the exiting laser beam is not displaced from the original beam direction or position. The beam scanner may be inserted into an existing optical resonator, for example, without modifications thereto.

Abstract: Two solid state laser structures are provided which are optimized for multimode operation. The first laser structure has a plurality of normal incidence optically transmissive surfaces in the laser cavity. The most reflective one of those normal incidence surfaces is disposed at the optical center of the laser cavity. The gain medium is centered in the subcavity defined by a cavity mirror and the optical center. In the second laser structure, there are no normal incidence surface in the laser cavity, and the gain medium is disposed at the optical center of the laser cavity. The laser structures are employed to construct erbium glass lasers which are not only optimized for multimode operation but also have effective cooling of the gain medium and minimized thermal lensing effect.

Abstract: A laser system in which an intense laser beam of a predefined pumping wavelength traverses a non-linear material, such as crystalline lithium niobate, that has been impressed with one or more quasi phase matching (QPM) gratings is disclosed. Quasi phase matching compensates for the dispersion or birefringence in a non-linear material by modulating the non-linearity with the proper period such that the different wavelengths involved in the non-linear process stay in phase over a long interaction length. The first QPM grating promotes the parametric generation of a resonant signal whose wavelength is determined by the grating period. According to the invention, either a second QPM grating impressed in the same medium or a different order of the first QPM grating promotes the non-linear interaction between the resonant signal and another optical signal traversing the non-linear material.

Abstract: An optical wavelength converter that converts the wavelength of the fundamental wave emitted from a fundamental wave light source by causing the fundamental wave to enter a non-linear optical material. The converter has a filter that absorbs only one of two wavelength-converted waves which is emitted from the non-linear optical material in directions opposite to each other. In the converter, light transmission end faces of an element interposed between the filter and the non-linear are covered with an antireflection coating. Alternatively, instead of the filter, the converter has a reflecting optical element which reflects only one of two wavelength-converted waves which are emitted from the non-linear optical material in directions opposite to each other, and which causes the reflected wavelength-converted wave to travel along an optical path which does not return to the non-linear optical material.

Abstract: A single-frequency semiconductor laser diode structure and a method for its fabrication. The structure includes a built-in etalon, which limits the frequency of operation of the device to a very narrow frequency band. For an edge-emitting diode, the etalon is formed over a cleaved end face of the semiconductor diode structure, and light is emitted from an opposed cleaved end face. For a surface emitting diode, the etalon is formed as an additional plurality of layers between a plurality of semiconductor layers forming the diode and a substrate on which the structure is formed. Transverse channels formed in the structure have side surfaces that act as mirrors, at least one of which is angularly inclined to the plane of the active region, to reflect light through the etalon layers and out through a parallel exterior surface of the structure. Multiple surface emitting lasers may be arrayed in closely spaced relation to each other, to form a powerful light emitting array.

Abstract: A technique for the generation of picosecond (psec) and femtosecond (fsec) pulses from modelocked double-clad fiber lasers cladding pumped with broad area diode laser arrays is disclosed. Using an erbium/ytterbium fiber oscillator, 560 fsec pulses with pulse energies up to 40 pJ are generated at a wavelength of 1560 nm. In a dispersion-compensated cavity, pulses as short as 170 fsec with pulse energies up to 50 pJ are obtained. By adding a negatively chirped fiber Bragg grating for additional intracavity dispersion control, pulse widths of 3 psec with pulse energies up to 1 nJ are obtained. A saturable absorber is used for pulse start up, whereas nonlinear polarization evolution is exploited for steady-state pulse shaping. An environmentally stable design is ensured by employing birefringent fibers and a compensation scheme for linear and nonlinear polarization drifts in the cavity.

Abstract: A semiconductor laser emits semiconductor laser light with TM-mode oscillation. The emitted semiconductor laser light is collimated by a first collimating lens, passes through a Brewster plate that is arranged so that the direction of Brewster plane's p-polarized light is in alignment with the direction of polarization of the emitted semiconductor laser light, and is coupled to an incident portion of a wavelength-conversion waveguide by means of a focusing lens. While being guided through the waveguide, the emitted semiconductor laser light is converted into second-harmonic light by means of a polarization inversion region. Semiconductor laser light emanating from an emitting portion of the waveguide reflects from an output mirror towards a diffraction grating, for modulation in wavelength. Second-harmonic light emanating from the emitting portion of the waveguide is outputted from the output mirror.

Abstract: A lead frame 32 has projecting portions 36, 37 projecting in a right-and-left direction, like arms, from the sides of its broad end portion 32a. The projecting piece portions 36, 37 include mold region parts 36a, 37a that are molded within a flat type sealing resin member 35, and exposed piece portions 36b, 37b that are exposed to the outside from the sealing resin member 35. One of the exposed parts, 36b, has an arcuate segment 36c inscribed in a hypothetical circle drawn with radius R about the point of light emission, C, on an LD chip 1. The other exposed part 37b has an arcuate segment 37c inscribed in the hypothetical circle drawn with radius R. A semiconductor laser device having these arcuate segments can be fitted into a stepped accommodating hole of an instrument and set in place there, just as can a can type semiconductor laser device. The point of light emission, C, on the LD chip 1 is also fixed. Thus, neither a shift in the point of light emission, C, nor the peeling of resin arises.

Abstract: The disclosure if directed to a laser amplifier system utilizing a pair of scanning mirrors driven in tandem by piezo actuators. A control provided to directed between the pair of scanning mirrors. Each bounce of the laser beam between the mirrors discretely increases the power of the beam and changes the angle of exit of the beam from the amplifier providing for precise angular beam exit control.

Abstract: A miniaturized, frequency-doubled blue laser utilizing a pump source operating within a radiation band of 780 to 820 nm, such as a Ti:sapphire laser or other suitable optical pump, to pump a gain medium comprising a crystal of neodymium-doped yttrium orthoaluminate (Nd:YAlO.sub.3) and produce a fundamental radiation having a wavelength of approximately 930 nm, the fundamental radiation being subsequently frequency doubled by means of a nonlinear crystal, such as potassium niobate (KNbO.sub.3), to yield output radiation at a wavelength of 465 nm.

Abstract: A waveguide carbon dioxide (CO.sub.2) laser includes a six-sided laser block comprising first and second triangular end sections and a rectangular insert block. The two triangular end sections include a waveguide grid comprising two sets of parallel waveguide channels intersecting at right angles and optically coupled by strip mirrors disposed along the edges of the triangular sections. The rectangular insert block also includes a set of parallel waveguide channels which are congruent with and aligned parallel to the waveguide channels of the two triangular end sections, thereby extending the cavity length of a multiply folded waveguide laser without a corresponding increase in the number of optical folds, the number of folding mirrors, or the value of distributed loss.

Abstract: A laser beam source radiates out laser beams such that they may intersect one another with predetermined angular spectra on a predetermined virtual plane. A Fourier transform lens array optical system, which is located in the vicinity of the virtual plane, divides the laser beams having impinged upon the virtual plane into small regions and carries out Fourier transform of the small regions. Phase modulators modulate the phases of the laser beams divided into the small regions such that the wave fronts of the laser beams after being subjected to the Fourier transform may have the same phase with respect to a predetermined direction as a whole. A scanning drive device drives the phase modulators such that the directions of travel of the laser beams radiated out of the Fourier transform lens array optical system may be changed. A first resonator mirror is located at a position that receives the scanned laser beams. A second resonator mirror is located at a position rearward from the laser beam source.

Abstract: A gas laser consisting of a single elongated piece of dielectric material (1), with two hermetically sealed parallel elongated chambers (2) and (3), and an opening (4) connecting the two chambers. One of the elongated chambers (2) is of a cross section suitable for confining a laser gas discharge. The other elongated chamber (3) is a reservoir for laser gas, which also functions to dampen the unwanted acoustic waves generated by the laser gas discharge and as a means of extending the operating lifetime of the laser gas. The opening connecting the two elongated chambers serves to dampen the acoustic waves generated by the laser gas discharge traveling the length of the elongated laser chamber and to stop unwanted low angle wall reflections of laser light energy traveling at a slight angle to the length of the laser chamber.

Abstract: A mirror mount assembly has a base plate positioned at one end of a laser resonator, and a movable plate spaced from and positioned substantially parallel to the base plate. One or more elastic springs are connected between the base plate and the moveable plate to provide tip and tilt of the movable plate and translation of the moveable plate away from or towards the base plate. The elastic springs include a bushing made of an elastic material, and at least three elastic dimples formed in the bushing circumferentially in a plane across a bushing longitudinal axis. Further, the elastic spring has a bushing made of an elastic material capable of elastic expansion and contraction. The bushing includes a threaded interior side and a longitudinal axis from a first open end of the bushing to a second open end of the bushing.

Abstract: A laser apparatus including a laser crystal composed of a fluoride which contains chromium (Cr), a resonator which includes the laser crystal, a means for exciting the laser crystal, a first laser beam produced from light which is emitted from the laser crystal and oscillated in the laser resonator, and at least one optical component which is inserted in said resonator; wherein an aperture in the resonator is substantially five or more times the diameter of the first laser beam. A small, low-power SHG laser light source is achieved.

Abstract: A monolithic diode pumped solid-state laser (11) comprising as the laser host neodymium-doped yttrium orthovanadate (Nd:YVO.sub.4) (12, 52) or neodymium-doped gadolinium orthovanadate (Nd:GdVO.sub.4) (57, 67) operating on the .sup.4 F.sub.3/2 .fwdarw..sup.4 I.sub.9/2 (.about.914 nm or .about.912 nm respectively) transition, to which a suitable nonlinear optic material (16), such as potassium niobate (KNbO.sub.3) or beta barium borate (BBO), is bonded. The nonlinear crystal gives rise to intracavity frequency doubling to .about.457 or .about.456 nm. The microlaser is a composite cavity formed from a gain medium crystal and a nonlinear frequency doubling material which together have four spaced parallel dielectrically coated faces (14, 17, 18, 15) and which is positioned in close proximity to a diode laser pump source (13) for phase-matched harmonic generation of blue light along an axis of propagation which lies substantially perpendicular to the two faces of the composite cavity.

Abstract: The invention provides a laser system with one or several micro-mechnically produced, actively controlled laser mirrors which are provided with an actuation device, so that the rapid manipulation of small laser mirrors is assured. The mirrors are designed so that they permit an economical production in large numbers.

Abstract: A large-area semiconductor laser diode in an extended laser cavity is locked by a passive optical coupling to a passive resonator for frequency and amplitude stable buildup of an intracavity field in the passive resonator. The large-area laser diode may be a broad-area diode, a phased array, or a tapered amplifier. The extended laser cavity may be a linear cavity, or a ring cavity in either a double-pass or a single-pass configuration. Spatial beam cleanup and passive locking are simultaneously achieved. The concentrated power in the passive resonator is useful for accomplishing second harmonic generation, frequency summing and the like at high levels of efficiency and at low noise levels resulting from the frequency and amplitude stability within the passive resonator.

Abstract: A laser device which comprises a base having an optical channel, a laser diode pump source mounted to the base and in thermal conductive relation thereto, the laser diode pump source positioned in alignment with the optical channel, a laser gain medium mounted in the optical channel and capable of being excited to establish a lasing condition, a lens mounted in the optical channel and positioned between the laser diode pump source and the laser gain medium and aligned with the laser diode pump source and the laser gain medium, a power supply for energizing the laser diode pump source to produce a lasing condition therein to produce an output of lasing energy, the output directed to the lens and focused on the laser gain medium to excite the laser gain medium to establish a lasing condition for producing a beam, and a mirror mounted in alignment with the optical channel adjacent the laser gain medium.

Abstract: The invention is for a new type of an efficient and compact laser system, based on semiconductor gain medium, which produces high peak power.

Abstract: A pulsed laser comprises an oscillator (10), a laser medium (14), a wavelength selective member (12) for tuning the wavelength of a beam pulse (18) emitted by the oscillator, and means for pulsed excitation of the laser medium (14). The laser medium (14) is excited at least twice at consecutive times to generate a single beam pulse (18).

Abstract: A narrow-band laser apparatus comprises an optical resonator including first and second reflectors for reflecting radiation, a laser medium for amplifying radiation in said resonator and an etalon for selecting a given wavelength component from said radiation. A polarizing beam splitter is provided for linearly polarizing said radiation and also for acting as an output coupler. In order to obtain very narrow bandwidth radiation of high intensity, a Faraday rotator is provided for rotating the plane of polarization while maintaining the linear polarization thereby allowing a second wavelength selection element (such as a grating) to be efficiently employed to further narrow the output of the laser.

Abstract: The present invention is directed to an unstable laser resonator. The present invention includes a first mirror located adjacent one end of a laser gain medium, and a second output mirror/lens where one surface acts as a mirror and the other surface acts as a collimating lens located adjacent an opposite end of a laser gain medium. Both mirrors include combinations of convex, concave and plano surfaces in order to achieve small fresnel number light with diffraction limited light properties and high energy extraction associated with a large fresnel number. The output coupler provides a means to extract and collimate the light out of the cavity and feedback into the laser gain medium high quality laser light for sustaining the diffraction limited performance while the gain medium is excited.

Abstract: A solid state laser apparatus and a laser machining apparatus are provided to provide high power laser beam having an excellent condensing performance at high efficiency and with high reliability. In the solid state laser apparatus, a recess is provided in a supporter disposed on a slab side surface at an excitation area corresponding portion. A high reflectance body having a cooling water filtrating groove is disposed in the recess to contact with a slab facing surface with pressure. The supporter contacts slab longitudinal both ends with pressure through a silicon rubber plate which is transparent to excitation light. A transparent silicon rubber O-ring is disposed to extend over an entire peripheral portion of a plane formed by a slab surface including the supporter pressure contacting porting and the supporter so as to seal cooling water and elastically support the slab.

Abstract: The purpose of the present invention is to provide an external resonator type wavelength-variable semiconductor laser light source adopting a "sine bar" method, in which the oscillation wavelength of the semiconductor laser can be varied within a wide range under phase-continuous conditions. In the external resonator type wavelength-variable semiconductor laser light source according to the present invention, the semiconductor laser outputs an outgoing beam from one end face coated with an antireflection film. The outgoing beam transmits the first and second prisms to be incident on a diffraction grating fixed on a rotating stage. When the second prism slides on a slope of the first prism, an arm which is connected to the second prism works together, and the diffraction grating rotates. At this time, the optical length of the beam which transmits the second prism changes, while the length of resonator does not change.

Abstract: A gas laser 1 such as a .sup.13 CO.sub.2 -laser emits at two different wavelengths (.lambda..sub.1, .lambda..sub.2) with a sine-shaped adjustment of a resonator mirror or a grating 13 such as a Littrow grating. The gas laser emits radiation at the two desired wavelengths (.lambda..sub.1, .lambda..sub.2) in two mutually adjacent intervals of the resonator length L because of a suitable dimensioning of the grating 13 with respect to grating structure and angle position, the outcoupling factor of the outcoupling mirror 12, the resonator length L and the composition of the gas of the laser. The laser emission is inhibited at the crossover between the two intervals and the sine-shaped modulation (for example with a piezo element) of the resonator length L is essentially symmetrical about this crossover. The invention is also directed to an arrangement for detecting a substance such as NH.sub.3 in a flue gas.

Abstract: A single mode laser with a laser cavity consisting of an active medium and a first and second reflectors with an antiguide region or layer having a high refractive index positioned adjacent to the laser cavity to bleed off higher order lasing modes and preventing them from attaining the lasing condition. Specifically, light belonging to higher order modes leaks or bleeds into the antiguide region from the laser medium and from the first and second reflectors. When spacers for selecting the desired wavelength of laser light are provided, the light travelling through them leaks into the antiguide layer as well.Optimization of the bleeding of higher order modes into the passive antiguide region can be achieved by adjusting a taper angle of the laser cavity. Furthermore, by adjusting the ratio of the equivalent refractive index of the laser cavity and the passive antiguide region single mode operation at high current levels can be realized for apertures as large as 30 .mu.m.

Abstract: A method and apparatus for producing stimulated emission from a laser gain element containing an organic dye are described in which optical pumping is produced by visible laser diodes. Low threshold pump power and high optical conversion efficiency are achieved by producing a laser resonator mode waist at or near the laser gain element and spatially superimposing a pump mode waist at or near the laser resonator mode waist. Using low power visible AlGaInP laser diodes and the dyes rhodamine 700, oxazine 750, DOTCI or oxazine 1 in the laser gain element, incident pump threshold powers as low as 5.4 mW, optical conversion efficiencies of 49% and tunable emission between 700 nm and 800 nm were achieved. This laser was scaled to higher cw output power by using a DCM-based pump dye laser. In a preferred embodiment the laser resonator has two reflective elements in a nearly hemispherical configuration. Angular multiplexing of laser diodes to scale to higher laser diode pump power is described.

Abstract: A fraction of the theoretical spot size in a lens system is obtained by applying a filter consisting of a variable pitch circular grating, in front of the focus lens. The focal point Image of a lens is a spot called an Airy disk. The diameter of the Airy disk is proportional to (wavelength)/(Numerical Aperture). Numerical aperture is equal to (1/2 of the diameter of the lens)/(focal length). This is the theoretical limit of spot size. Using a Bessel Transform, modified circular grating, filter the resulting first and higher order diffraction images lie on the optical axis and interfere resulting in a small beam spot at the focus surrounded by interference bands, producing a narrowed zero order beam for projection in optical and infrared applications.

Abstract: A laser apparatus having a laser that generates at least one laser beam of a fundamental wavelength, a diffractive optical element that converts the laser beam into a plurality of light beams at the fundamental wavelength, and a harmonic crystal that converts the plurality of light beams at the fundamental wavelength into respective light beams having respective wavelengths which are harmonically related to the fundamental wavelength. By splitting the laser beam into a plurality of beams before converting to harmonic wavelengths using the harmonic crystal, the crystal volume is more efficiently used and the thermal stress on the crystal is reduced. In an alternative embodiment, the invention provides for the use of a plurality of harmonic crystals in series to convert the wavelength to shorter harmonics.