Abstract: A two-wavelength semiconductor laser device includes a first conductive material substrate having thereon first and second regions separated from each other. A first semiconductor laser diode is formed on the first region. A non-active layer is formed on the second region and has the same layers as those of the first semiconductor laser diode. A second semiconductor laser diode is formed on the non-active layer. A lateral conductive region is formed at least between the first and second semiconductor laser diodes.

Abstract: To optimise the transformation rate (efficiency) in the optical frequency conversion of laser beams of ultra-short light pulses in optically non-linear media such as a crystal (56), a double refracting crystal (54) is arranged in the beam path before the optically non-linear medium (56). The length of the double refracting crystal (54) is selected and the orientation of its optical crystal axis in relation to the propagation direction of the laser beams involved in the frequency conversion is set such that the change caused by the double refracting crystal (54) in the location, time and direction of incidence of the laser pulses (14) and (16) on the optically non-linear medium (56) and the resulting change in the spatial and temporal overlap of the laser pulses in the optically non-linear medium (56) for optical frequency conversion in the crystal (56) give a conversion efficiency which is higher than the conversion efficiency which would be achieved without the double refracting crystal (54).

Abstract: A multi-section laser diode control system comprising a multi-section laser diode (10), microprocessor controller (24), digital-to-analogue converter (28), driver circuit (30) and wavelength locker (14) is modified by inclusion of a locking circuit (40) which generates an analogue correction signal . . . 1 V ph responsive to measurements of the laser output made by the wavelength locker. The analogue correction signal is added to the preset phase voltage V ph asserted by the microprocessor controller to provide fast feedback that bypasses the microprocessor controller. This novel feedback is made possible by avoiding the use of the standard prior art control algorithm which requires a division calculation to be performed. Instead, novel control algorithms based purely on additions, subtractions and multiplications are used. The laser can thus be locked to its target output frequency without having to place slow analogue-to-digital and digital-to-analogue converters in the feedback control path.

Abstract: Dual-wavelength operation is easily achieved by biasing the gain section. Multiple gratings spaced apart from each other are separated from an output aperture by a gain section. A relatively low coupling coefficient, ?, in the front grating reduces the added cavity loss for the back grating mode. Therefore, the back grating mode reaches threshold easily. The space section lowers the current induced thermal interaction between the two uniform grating sections, significantly reducing the inadvertent wavelength drift. As a result, a tunable mode pair separations (??) as small as 0.3 nm and as large as 6.9 nm can be achieved.

Abstract: A pulse sequence is configured by making a pulse waveform output from a pulse light source into a super Gaussian pulse of the third order or higher, and input to a spectrum expanding device. The spectrum expanding device broadens the spectrum of the pulse sequence with a nonlinear medium. A modulator array extracts longitudinal mode components from the expanded spectrum, and modulates the extracted longitudinal mode components with modulation data. Lastly, the modulated longitudinal mode components are coupled and transmitted to a transmission line.

Abstract: Lasers, such as in laser structures, can include two or more semiconductor structures that are substantially identical or that include the same semiconductor material and have substantially the same geometry, such as in closely spaced dual-spot two-beam or quad-spot four-beam lasers. The lasers can also include differently structured current flow or contact structures or different wavelength control structures. For example, current flow or contact structures can be differently structured to prevent or otherwise affect phase locking, such as by causing different threshold currents and different operating temperatures.

Abstract: A semiconductor laser device for emitting light at two wavelengths ?1 and ?2 comprises: a laser chip having a front end face and a rear end face; and a high reflectance film on the rear end face of the laser chip and including seven or more layers laminated one on top of another, the seven or more layers including a first layer and a last layer, the first layer being closest to the laser chip, the last layer being farthest from the laser chip. One or more of the seven or more layers of the high reflectance film, other than the first and last layers, has an optical thickness of n*?/2, where n is a natural number and ?=(?1+?2)/2. All of the seven or more layers of the high reflectance film, other than the one or more layers and other than the last layer, have an optical thickness of (2n?+1)*?/4, where n? is 0 or a positive integer. The last layer of the high reflectance film has an optical thickness of n*?/4.

Abstract: An integrated circuit lithography technique called spectral engineering by Applicants, for bandwidth control of an electric discharge laser. In a preferred process, a computer model is used to model lithographic parameters to determine a desired laser spectrum needed to produce a desired lithographic result. A fast responding tuning mechanism is then used to adjust center wavelength of laser pulses in a burst of pulses to achieve an integrated spectrum for the burst of pulses approximating the desired laser spectrum. The laser beam bandwidth is controlled to produce an effective beam spectrum having at least two spectral peaks in order to produce improved pattern resolution in photo resist film. Line narrowing equipment is provided having at least one piezoelectric drive and a fast bandwidth detection control system having a time response of less than about 2.0 millisecond.

Abstract: An all-fiber device platform for producing high-power ROGB or RGB laser output comprises an optical fiber including multiple waveguide gain regions embedded within a common inner cladding and within an outer cladding, an optical cavity defined by dielectric reflectors and/or FBG mirrors, and a pump source for exciting one or more active ionic species by one or multiple pump wavelengths from one or both ends of the optical fiber through upconversion process. An apparatus for producing sequential or simultaneous multiple wavelength laser operation provides for applications of color projection displays and biomedical or other instrumentation.

Abstract: A device for generating a light beam having several wavelengths includes a beam recombiner arrangement for recombining several laser light beams having different wavelengths. The beam recombiner arrangement includes several individual beam recombiners arranged in a row or in groups parallel to each other and each configured to couple in a respective laser light beam having a wavelength of a defined wavelength range.

Abstract: Optical filaments are formed controllably in a gaseous medium such as air. A phase plate introducing a phase discontinuity or other localized optical inhomogeneity is introduced into the path of the pulsed high-power laser beam that forms the optical filaments in the medium. The locations and characteristics of the phase discontinuities or singularities are selected to control the number and locations of the optical filaments.

Abstract: The present invention relates to wavelength tunable DBR semiconductor laser devices in which light waves generated from a plurality of laser portions (or laser channels) are combined. This type of semiconductor laser device requires that the laser channels together cover an entire desired wavelength range, allowing the oscillation wavelength to be continuously varied over this range. However, to accomplish this, it is necessary to employ highly accurate crystal growth and process techniques. Furthermore, the length of the gain region must be reduced to increase the range over which the oscillation wavelength can be continuously varied, making it difficult to achieve laser oscillation. Two laser channels operate in combination, and a combiner combines the light waves emitted from these laser portions (or laser channels) so as to cover one entire wavelength range.

Abstract: A laser apparatus capable of emitting laser beams of a plurality of different wavelengths includes: a solid-state laser medium which emits light of a plurality of different peak wavelengths; a resonance optical system which resonates the emitted light of the plurality of different peak wavelengths and converts respective light to oscillate the laser beams of the plurality of different wavelengths; and a ¼ wave plate for a wide band, which is placed in the resonance optical system and has a property of providing a uniform phase difference to the light of the plurality of different peak wavelengths to be converted.

Abstract: An ultraviolet laser is provided that increases the conversion efficiency of laser beams when harmonics having wavelengths of less than 355 nm are generated by converting laser beams with a wavelength conversion element made of a single crystal of lithium tetraborate. A wavelength conversion element is heated and controlled to a specific temperature (for example, 200° C.) within a temperature range of 200 to 450° C. with a predetermined temperature precision.

Abstract: The invention is in the field of distributed Raman amplification for digital and analog transmission applications and other applications, e.g., instrumentation and imaging applications, including HFC-CATV applications. In particular, the invention uses a high power broadband source of amplified spontaneous emission (ASE) as the Raman pump source for improved system performance. The invention also includes methods for constructing such a high-power broadband Raman pump.

Abstract: A direct write holographic printer for producing RGB color reflection holograms is disclosed. A Nd:YLF crystal (1) in a laser cavity is excited to produce an emission at 1313 nm which is frequency converted by doubling to 656.5 nm and by tripling to 437.7 nm. In a separate cavity a similar Nd:YLF crystal (1a) is synchronously or asynchronously excited to produce an emission at 1047.1 nm (or at the related line of 1053 nm) which is frequency converted by doubling to 523.6 nm (or 526.5 nm). The emissions at 437.7 nm and 656.5 nm are combined co-linearly with the emission at 523.6 nm (or 526.5 nm) to produce a single RGB pulsed laser beam.

Abstract: An optical wavelength grating coupler incorporating one or more distributed Bragg reflectors (DBR) or other reflective elements to enhance the coupling efficiency thereof. The grating coupler has a grating comprising a plurality of scattering elements adapted to scatter light along a portion of an optical path, and the one or more DBRs are positioned with respect to the grating such that light passing through the grating towards the substrate of the grating coupler is reflected back by DBRs toward the grating. The DBR comprises a multilayer stack of various materials and may be formed on the substrate of the grating coupler. The grating coupler may include a gas-filled cavity, where the cavity is formed by a conventional etching process and is used to reflect light toward the grating. The grating coupler may also incorporate an anti-reflection coating to reduce reflective loss on the surface of the grating.

Abstract: An optical fiber laser has an output that is stabilized to adapt to changes in laser operating temperature. At the output of the laser a plurality of wavelength-selective stabilizing reflectors is provided, each having a reflectivity profile with a different center wavelength. The reflectors, typically Bragg gratings, have a relative degree of reflectivity and relative wavelength separation that results in the output power of the laser being at one or more of the reflector center wavelengths throughout the temperature change. Thus, as a temperature shift causes the wavelength of the optical energy generated in the laser gain medium to change, the grating-stabilized output of the laser shifts between one locked wavelength and another. However, the output remains stable over the extended wavelength range provided by the multiple reflectors. Such a laser is particularly useful in an amplifier system in which the laser is used as an optical pump source.

Abstract: A traveling-wave ring laser resonator includes one or more gain-elements for generating fundamental radiation and three optically nonlinear crystals. A portion of the fundamental radiation is converted to second-harmonic radiation in a first of the crystals. Remaining fundamental radiation and the second-harmonic radiation traverse a second of the optically nonlinear crystals where a portion of each is converted to third-harmonic radiation. Fundamental and second-harmonic radiation pass through the third of the optically nonlinear crystals where most of the second-harmonic radiation is converted back to fundamental radiation. The third-harmonic radiation can be delivered from the resonator as output radiation or mixed with the fundamental radiation in a fourth optically nonlinear crystal to generate fourth harmonic radiation. An optical parametric oscillator arrangement is also disclosed.

Abstract: A surface emitting semiconductor laser system having four cavities that couple light from a single aperture. Each of the four cavities overlaps at the outcoupling aperture. Each cavity is fabricated to resonate at a different central wavelength, outputting a different frequency of light, each of which can be independently modulated.

Abstract: In a laser apparatus, a rotatable reflection mirror rotatable on or parallel to a resonance optical axis of a laser medium is disposed changeably between a first and second positions by driving of a rotating unit. A first resonance optical system includes a first and second resonant mirrors placed so that the laser medium and the rotatable reflection mirror disposed in the first position are interposed therebetween to resonate light of a first peak wavelength among the peak wavelengths emitted from the laser medium, the first peak wavelength light being to be reflected by the rotatable reflection mirror in the first position between the laser medium and the second resonant mirror, and a first wavelength converting element located between the rotatable reflection mirror disposed in the first position and the second resonant mirror to oscillate second harmonic light of the first peak wavelength light as a first laser beam.

Abstract: Methods and apparatus for generating a frequency comb and for its use in analyzing materials and in telecommunications. The frequency comb is generated by passing pulsed light from a laser through an optical fiber having a constriction. The frequency comb comprises a plurality of monochromatic components separated in frequency by a substantially constant frequency increment. The monochromatic components are used to probe materials for analysis. In preferred embodiments, the materials are DNA, RNA, PNA and other biologically important molecules and polymers. Optical responses are observed and used to analyze or identify samples. In telecommunication applications, the individual monochromatic components serve as carriers for individual communication channels that can carry information of any of a variety of types, such as voice, data and images.

Abstract: Method and apparatus for stabilizing an optical carrier frequency of a generated carrier signal with respect to a target carrier frequency. The apparatus includes a multi-channel optical filter for filtering the generated carrier signal, thereby to provide a first filtered optical signal and a second filtered optical signal, each filtered optical signal including the portion of the generated carrier signal contained in a pass band surrounding a respective channel center frequency. The apparatus also includes a detection unit for determining an indication of a characteristic of the target carrier frequency in the first and second filtered optical signals, as well as a control unit for adjusting the optical carrier frequency of the generated carrier signal as a function of the difference in the indication of the characteristic of the target carrier frequency in the first and second filtered optical signals.

Abstract: A two-wavelength semiconductor laser device includes a first conductive material substrate having thereon first and second regions separated from each other. A first semiconductor laser diode is formed on the first region. A non-active layer is formed on the second region and has the same layers as those of the first semiconductor laser diode. A second semiconductor laser diode is formed on the non-active layer. A lateral conductive region is formed at least between the first and second semiconductor laser diodes.

Abstract: An optical bandwidth source for generating amplified spontaneous emission (ASE) across a selected wavelength range, the optical bandwidth source including a waveguide having a first end and a second end, and comprising a plurality of separate wavelength gain subsections arranged in a serial configuration between the first end and the second end so as to collectively form an active waveguide between the first end and the second end; wherein each of the wavelength gain subsections is configured to produce ASE across a wavelength range which is less than, but contained within, the selected wavelength range, whereby the plurality of separate wavelength gain subsections collectively produce ASE across the selected wavelength range.

Abstract: Optical filaments are formed controllably in a gaseous medium such as air. A phase plate introducing a phase singularity is introduced into the path of the laser beam that forms the optical filaments in the medium. The phase plate is preferably a vortex phase plate having one or more singularities. The locations and characteristics of the phase singularities are selected to control the number and locations of the optical filaments.

Abstract: Internal combustion engine with at least one cylinder, in which the combustion of a homogeneous air/fuel mixture compressed in the cylinder by a piston is initiated by a time-controlled external ignition, the air/fuel ratio of the air/fuel mixture in the combustion chamber (25) being greater than 1.9 and, for the time-controlled external ignition, at least one laser light source (10), at least one optical transmission apparatus (11) and at least one coupling optic (12) for the focussing of laser light into a combustion chamber (25) being provided.

Abstract: A high power multi-frequency laser includes a laser cavity defined by reflective elements, a frequency routing device in the cavity comprising a plurality of frequency selective pathways, a first set of optical amplifiers optically coupled to a first end of the frequency routing device, and a second set of optical amplifiers optically coupling a second end of the frequency routing device and a first one of the reflective elements. The high power multi-frequency laser further includes a power combiner. The power combiner is optically coupled to the first set of optical amplifiers and a second one of the reflective elements and combines the outputs of the first set of optical amplifiers such that a common output for the multi-frequency laser is provided. The common output of the present invention provides a single output from the multi-frequency laser having a high output coupling efficiency.

Abstract: A laser system capable of producing multiple groups of output wavelengths is disclosed. In one embodiment, an optical fiber bundle doped with erbium (Er) or erbium/ytterbium (Er/Yb) is perpendicularly attached to an optical device, which serves as a guided-mode resonance feedback mirror, to form a fiber laser matrix. The optical device contains a substrate layer, a waveguide layer, and a grating layer, with non-uniform device parameters. The wavelength of the resonant light and its corresponding laser light of an individual optical fiber depends upon the parameters in the location on the optical device where the fiber is attached. In another embodiment, a plurality of active waveguides in a body are attached to an optical device to form a diode-pumped crystal laser matrix with multi-group output wavelengths. The invented laser system is capable of generating laser sources of large channel capacity for the optical network especially for the dense wavelength division multiplexing (DWDM) system.

Abstract: A pulsed multiple color laser system is disclosed having particular application for incorporation into a digital holographic printer for producing RGB color reflection holograms. A Nd:YLF crystal (1) in a laser cavity is excited to produce an emission at (1313) nm which is frequency converted by doubling to 656.3 nm and by tripling to 437.7 nm. In a separate cavity a similar Nd:YLF crystal (1a) is synchronously or asynchronously excited to produce an emission at 1047.1 nm (or at the related line of 1053 nm) which is frequency converted by doubling to 523.6 nm (or 526.5 m). The emissions at 437.7 nm and 656.5 nm are combined co-linearly with the emission at 523.6 nm (or 526.5 nm) to produce a single RGB pulsed laser beam.

Abstract: A laser source includes a laser medium having a back facet and a front surface, whereby the laser medium is adapted to emit a laser beam through the front surface into an external cavity defined in length by a cavity end mirror reflecting the laser beam back towards the laser medium. A wavelength tunable filter is arranged between the laser medium and the cavity end mirror adapted for tuning the wavelength of the laser beam. The laser medium, the wavelength tunable filter, and the cavity end mirror are arranged in a spatially linear cavity structure substantially in a line without angular redirection of the laser beam in the cavity between the laser medium and the cavity end mirror. At least one portion of the laser beam within the cavity after passing the wavelength tunable filter and before again passing the laser medium is coupled out as an output beam of the laser source, and the cavity end mirror is provided to be partly transparent for coupling out a first output beam.

Abstract: A laser imaging system with reduced speckle is disclosed. The laser imaging system includes spatially superpositioned 1-D arrays or alternatively 2-D arrays of independent emitters of laser radiation, with each emitter having a spectral bandwidth ??i centered at some arbitrary wavelength ?0i. The elements of the array are allowed, by design, to have a slightly different central wavelength, thereby creating an ensemble bandwidth ?? which is much greater than the bandwidth ??i of any individual emitter in the array. The resulting increased bandwidth reduces speckle in a displayed image.

Abstract: A device including a photon emitter, a light source, and a filter with a corresponding method for producing triggered single photons and triggered pairs of polarization-entangled photons are provided. The light source delivers a pulse to a photon emitter and generates pairs of electrons and holes to emit photons. The light source includes a mechanism to tune a pulse wavelength to an excited state-absorption resonance of the photon emitter. The light source could also include a device to selectively choose a polarization to create the pairs of electrons and holes of a particular spin. A filter isolates the last and single photon. Optionally, a micro-cavity is included to direct the emitted photons and couple to one or more optical elements. When the device or the method is used to produce triggered pairs of polarization-entangled photons, it works almost the same as for the single photons, except for modifications to the way the light source excites the photon emitter and how emission filtering is performed.

Abstract: The present invention relates to an arrangement of semiconductor diode lasers stacked on top of one another, which is arranged on a substrate (1). A first diode laser (12) is arranged on the substrate (1), and a second diode laser (13) is arranged on the first diode laser (12). Between the first diode laser (12) and the second diode laser (13) there is a contact layer (6). The contact layer (6) comprises a first conductive layer (18) of a first conduction type and a second conductive layer (20) of a second conduction type and an interlayer (19) which is arranged between the first and second conductive layers (18, 20).

Abstract: A multi-beam semiconductor laser device capable of emitting respective laser beams with uniform optical output levels and enabling easy alignment is provided. This multi-beam semiconductor laser device (40) is a GaN base multi-beam semiconductor laser device provided with four laser stripes (42A, 42B, 42C and 42D) which are capable of emitting laser beams with the same wavelength. The respective laser oscillating regions (42A to 42D) are provided with a p-type common electrode (48) on a mesa structure (46) which is formed on a sapphire substrate (44), and have active regions (50A, 50B, 50C and 50D) respectively. Two n-type electrodes (52A and 52B) are provided on an n-type GaN contact layer (54) and located as common electrodes opposite to the p-type common electrode (48) on both sides of the mesa structure (46). The distance A between the laser stripe (42A) and the laser stripe (42D) is no larger than 100 ?m.

Abstract: A subject of the invention is to reduce the temperature dependence of an etalon as a wavelength locker for a semiconductor laser device and so forth. Concretely, it is to restrict the lowering of the wavelength locking performance of the etalon dependent on the temperature variation. A means to solve the subject is the use of an air gap etalon. Concretely, the means is provided with a media plate and parallel plane plates on both sides of the media plate. The two parallel plane plates and the space between them constitute the air gap etalon.

Abstract: A diode-pumped solid-state laser oscillator optically pumps a laser medium. The oscillator has at least one pumping light source that emits light in a predetermined wavelength band, and a laser medium that absorbs light in the wavelength band. In the wavelength band, the optical absorption index of the laser medium increases with an increase in wavelength, and the optical radiation energy of the light source decreases with an increase in wavelength. Thus, with respect to wavelength changes, an increase in the optical absorption index is cancelled out by a decrease in the radiation energy, making the stability of the laser output less dependent on the temperature of the optical pumping medium or laser medium.

Abstract: An external cavity laser (and method of generating laser light) comprising: a laser light source; means for collimating light output by the laser light source; a diffraction grating receiving collimated light; a cavity feedback mirror reflecting light received from the diffraction grating back to the diffraction grating; and means for reliably tuning the external cavity laser to discrete wavelengths.

Abstract: An optical pickup apparatus and a laser diode chip which can simplify and miniaturize a construction of the apparatus is provided for using a plurality of laser beams of different wavelengths. The laser diode chip is a chip for the optical pickup apparatus in which a plurality of light emitting portions for emitting the laser beams of the different wavelengths in the same emitting direction are formed on a substrate. Light emitting points of the plurality of light emitting portions are located at positions which are different in the emitting direction.

Abstract: A method and circuit for measuring the optical modulation amplitude in the operating region of a laser diode is described. The method utilises two measurements of OMA, each measurement being related to the slope in a specific portion of the operating region of the power/current characteristic curve of the laser diode. By combining the two measurement values, the invention provides a 1 measurement for OMA in the operating region of the laser diode that allows for the presence of a non-linear response in the region.

Abstract: Wavelength lockers, which monitor the wavelength drift of a laser's beam due to aging, are tunable to adjust for manufacturing misalignments between its various optical components. Tuning is accomplished by adjusting the position of a collimating lens using a flexure. Adjusting the lens position changes the angle of incidence of a monitored beam relative to a fixed filter and detector and avoids the challenging manufacturing task of rotating the filter and detector to achieve the same result.

Abstract: Two thin-clad laser diodes are disposed to form a stack-type device that emits two beams. The beams are substantially parallel and in proximity such that they share many fiberoptic systems designed for a single beam. In one embodiment the device functions as a dual-wavelength fiber-pigtailed light source. In another embodiment a feedback mechanism is provided to couple the diodes. Other embodiments include structures and methods for output power enhancement and tunable lasers.

Abstract: A tunable laser device produces a laser energy over a range of frequencies. A property of an ultrasonic transducer or, more specifically, the frequency of an ultrasonic wave created by the ultrasonic transducer is altered to change the laser frequency of the tunable laser device. The ultrasonic transducer may couple its ultrasonic wave directly into the laser source or may form a tunable acousto-optic modulator external to the laser source. In both cases, the ultrasonic wave creates an index of refraction perturbation in an optical substrate, through which the laser energy of the laser source passes. Changes in the ultrasonic wave cause changes in the perturbation through which the laser energy passes, which in turn, changes the frequency of the laser energy, thereby enabling the frequency of the laser to be tuned.

Abstract: A resonant-cavity light-emitting diode includes a semiconductor light-emitting layer sandwiched between an under and an upper semiconductor distributed Bragg reflector mirror layer, which are formed on the substrate, a light extracting section formed on the upper semiconductor distributed Bragg reflector mirror layer and having an opening to extract light from the semiconductor light-emitting layer, and a groove formed by removing portions of the semiconductor light-emitting layer, under and upper semiconductor distributed Bragg reflector mirror layers which lie in a peripheral portion of the opening of the light extraction section and reach the under semiconductor distributed Bragg reflector mirror layer, the inner wall of the groove being formed to reflect part of light emitted from the semiconductor light-emitting layer into the groove.

Abstract: Method of generating laser pulses using a semiconductor laser diode as a lasing amplification medium of an extended laser cavity are presented. Passive self-modulated mode-locked operation of the semiconductor laser diode is achieved by providing an above lasing threshold direct current input current to the semiconductor laser diode while the semiconductor laser diode is operational in a slightly misaligned extended laser cavity favoring the amplification of wavelengths shorter than a center wavelength of a continuous wave operational mode of the semiconductor laser diode at threshold.

Abstract: A harmonic wave generator including a light source to generate a fundamental wave having a predetermined wavelength, a non-linear material to transform at least a portion of the fundamental wave generated by the light source into a harmonic wave having a shorter wavelength than the fundamental wave, and a first optical device to separate the harmonic wave generated by the non-linear material from the fundamental wave. The harmonic wave generator further includes a second optical device between the condensing lens and the non-linear material to adjust the depth of the focus of light. The harmonic wave generator is easily assembled and can be manufactured at a low cost. A harmonic wave having high power can be generated.

Abstract: A semiconductor electrooptic monolithic component comprising successively a first section capable of emitting light at a first wavelength and including a first active layer, a second section capable of absorbing light at the said first wavelength and including a second active layer, and a third section capable of detecting light at a second wavelength and including a third active layer. The component is characterized in that the second active layer is designed to ensure in the said second section an absorption higher than that which would be allowed by an active layer identical to the said first layer.

Abstract: The present invention relates to a cascaded multi-wavelength Raman fiber laser adapted for emitting radiation of at least one wavelength &lgr;s1, with a length of optical fiber (13) having input (15) and output (16) sections, means (11) for introducing pump radiation of wavelength &lgr;p into said length of optical fiber (13), at least one pair of spaced-apart reflector means (151,161; . . .

Abstract: A multi-wavelength surface emitting laser for emitting light having different wavelengths includes a lower reflector, an active layer and an upper reflector which are integrally formed above one substrate. The multi-wavelength surface emitting laser is manufactured by forming a first surface emitting laser, partially removing a first upper reflector, a first active layer, and a first lower reflection layer by etching. A protection film is formed on the outer surface of the first surface emitting laser. A second surface emitting laser is formed by removing a second lower reflector, a second active layer, and a second upper reflection layer formed on the protection film by etching. The protection film is removed and first and second upper electrodes are formed on upper surfaces of the first and second upper reflection layers, respectively, and a lower electrode is formed on a bottom surface of the substrate.

Abstract: A direct diode laser system includes N laser head assemblies (LHAs) generating N output beams, N optical fibers receiving respective N output beams and generating N received output beams, and a torch head recollimating and focusing the N received output beams onto a single spot. Preferably, each of the laser head assemblies of the direct diode laser system includes M modules generating M laser beams, wherein each of the M laser beams has a corresponding single wavelength of light. M-1 dichroic filters, wherein each of the M-1 dichroic filter transmits a corresponding one of the M laser beams and reflects all other wavelengths, and a fiber coupling device collecting the M laser beams to produce a respective one of the N output beams. In an exemplary case, the M-1 dichroic filters function as band pass filters. A method of generating a high fluence, high power laser beam is also described.