Abstract: A laser system and method having an output laser beam uses an gain medium with one or more output beam transverse profile tailoring (OBTPT) longitudinal strips to tailor the transverse profile of the output laser beam to a desirable shape such as having a symmetrical profile transverse to the direction of propagation of the output laser beam. The laser system has two reflector systems on opposite ends in the long z-axis dimension of the gain medium to form a resonator that outputs the output laser beam following the same long z-axis dimension. In some embodiments the gain medium has a narrow y-axis dimension and a wide x-axis dimension. In these embodiments the OBTPT longitudinal strips have lengths running the long z-axis dimension, widths running the wide x-axis dimension and thicknesses running the narrow y-axis dimension of the gain medium. The widths of the OBTPT longitudinal strips are generally chosen with respect to coupling width of the output laser beam.

Abstract: In a semiconductor laser element having a semiconductor substrate, and a crystal layer formed on a main surface of the semiconductor substrate, the crystal layer having in its inside a waveguide, a light-emitting point alignment mark is provided on an intersection line of an electrode surface of the semiconductor laser element with a plane which includes the waveguide and which is perpendicular to the electrode surface. The light-emitting point alignment mark having a length in a width direction of the semiconductor laser element of not more than 20 &mgr;m. A visually recognizable direction indicating mark is also provided on the same side as the light-emitting point alignment mark in a direction in which the waveguide extends.

Abstract: A system and method for laser beam coupling between waveguide optics uses extension members to reduce power losses in a laser beam traveling within a resonator cavity of the laser beam. In some embodiments, the extension members are made of electrically conducting material and are spaced from longitudinal ends of electrodes by electrically insulating material. The electrically insulating material is sized to prevent electrical discharge from occurring between the electrode and the extension member adjacent thereto. In other embodiments, the extension members are fashioned from a lasing medium such as from a solid-state crystal lasing medium.

Abstract: A compression-tuned Bragg grating-based laser 800 includes a pair of optical grating elements 802,804 wherein at least one of the grating elements is tunable by a compression device 812,814. The grating elements may include either an optical fiber 10 having at least one Bragg grating 12 impressed therein encased within and fused to at least a portion of a glass capillary tube 20 or a large diameter waveguide grating element 600 having a core and a wide cladding. The tunable grating element(s) 802,804 are axially compressed, which causes a shift in the reflection wavelength of the gratings 807,809 without buckling the element. The shape of the element may be other geometries (e.g., a “dogbone” shape) and/or more than one grating or pair of gratings may be used and more than one fiber 10 or core 612 may be used. A gain element, such as Erbium doped fiber, is optical disposed between the grating elements to provide the lasing cavity.

Abstract: The method and apparatus operates to calibrate a transmission laser of the dense wavelength division multiplexer (DWDM). In one example, the transmission laser is a widely tunable laser (WTL) to be tuned to one of a set of International Telecommunications Union (ITU) transmission grid lines for transmission through an optic fiber. The WTL is tuned to the ITU grid using an etalon and a gas cell having acetylene, hydrogen cyanide or carbon dioxide. Initially, the absolute transmission wavelengths of the WTL are calibrated by routing an output beam from the WTL through the etalon and through the gas cell while varying tuning parameters of the WTL to thereby generate an etalon spectrum and a gas absorption spectrum both as functions of the tuning parameters. The etalon and gas absorption spectra are compared, along with input reference information specifying gas absorption as a function of absolute wavelength, to determine the absolute transmission wavelength for the WTL as a function of the tuning parameters.

Abstract: Continuously tunable and precisely wavelength-switchable fiber lasers combine fiber Bragg gratings and the transmissive filtering properties of high finesse fiber Fabry-Perot filters. This laser arrangement adapts to multiple wavelength ranges based on the selections of fiber Bragg grating and gain medium and their arrangement to create a wavelength-modulatable and simultaneously rapidly wavelength-switchable narrow linewidth all-fiber laser design. This laser arrangement further results in narrow-linewidth outputs with fast switching speeds between the selected wavelengths.

Abstract: An electro-absorption modulated laser is provided having three sections, a laser section, an isolation section, and a modulation section. The laser section produces light along a straight waveguide path. The modulation section also has a straight waveguide path, but is angled with respect to the laser section's path. The isolation section between the other two sections includes a path that is collinear with the respective laser or modulation section at each end, but is gradually curved in the middle.

Abstract: An object of the present invention is obtaining a semiconductor film with uniform characteristics by improving irradiation variations of the semiconductor film. The irradiation variations are generated due to scanning while irradiating with a linear laser beam of the pulse emission. At a laser crystallization step of irradiating a semiconductor film with a laser light, a continuous light emission excimer laser emission device is used as a laser light source. For example, in a method of fabricating an active matrix type liquid crystal display device, a continuous light emission excimer laser beam is irradiated to a semiconductor film, which is processed to be a linear shape, while scanning in a vertical direction to the linear direction. Therefore, more uniform crystallization can be performed because irradiation marks can be avoided by a conventional pulse laser.

Abstract: In a distributed feedback semiconductor laser having at least an active layer and a diffraction grating on a semiconductor substrate and so constructed that a current is injected uniformly over an axial direction of a resonator, a bandgap wavelength of the active layer in the neighborhood of a light outputting end or a backward end opposite to the light outputting end, is shorter than that in the other region of the active layer along the axial direction of the resonator.

Abstract: A tunable laser system comprises an externalcavity laser diode in combination with an optically coupled waveguide having a Bragg grating formed therein. The laser diode provides a gain medium characterized by a first band of wavelengths. A portion of the fiber and the grating help define an external resonant cavity. The grating limits the wavelengths exiting the external cavity to a second band that is typically much narrower than the first band. The grating region of the waveguide is thermally coupled to a heating element having an associated temperature controller for controllably varying the temperature of the grating region and thus changing the optical pitch of the grating and thus the second band. The grating region of the waveguide can alternatively, or additionally, be subjected to acoustic energy to change the optical pitch of the grating.

Abstract: A laser device includes a waveguide substrate having a plurality of folded waveguide paths, the folded waveguide paths having widths of no more than approximately 1 mm, the folded waveguide paths having a surface area to volume ratio of at least 4 mm−1. The laser can also include a re-entrant cavity adapted for surrounding the sides and bottom of the waveguide substrate and a plate layer having an electrode array formed from a plurality of conductive traces aligned with the waveguide paths. A method for forming a laser device includes the steps of providing a waveguide substrate and forming a folded waveguide structure from a plurality of intersecting folded waveguide paths in the waveguide substrate, the folded waveguide paths having widths of no more than 1 mm, the waveguide paths having a surface area to volume ratio of at least 4 mm−1.

Abstract: A tunable external cavity semiconductor laser incorporating a tunable Bragg grating, including: a semiconductor gain medium; an elongated tuner housing having a tuner housing head and having a tuner housing foot, the tuner housing head and tuner housing foot being rigidly connected; a span of waveguide having a Bragg grating, for receiving the source light and for providing in turn the reflected light, and having a waveguide head and a waveguide foot, the waveguide head abutting the tuner housing head and the waveguide foot disposed toward the tuner housing foot; a piezoelectric crystal or other device or arrangement for providing a compressive force, disposed so as to abut the waveguide foot and also to abut the tuner housing foot, the means for applying a compressive force for exerting a compressive force on the span of waveguide along the direction of the axis of the span of waveguide, the compressive force being sufficient to alter the grating so as to affect the wavelength of light reflected by the grati

Abstract: The invention provides a chip for separating light into different wavelengths. The chip includes a substrate, an input waveguide, an optical arrangement, and a plurality of output waveguides. The substrate has first and second edge sections. The input waveguide is formed on the substrate and has an end for providing light thereto located at the first edge section. The input waveguide extends from the first end thereof in a first direction. The optical arrangement receives the light from the input waveguide and separates the light into a pattern of light of different wavelengths. The output waveguides are formed on the substrate. Each output waveguide receives light of a respective wavelength from the optical arrangement and transmits the light. Each output waveguide has an end, from which the light is transmitted, located at the second edge section. Each output waveguide extends to the second end thereof in a second direction. The second direction is different from the first direction.

Abstract: A method of temperature stabilizing an optical waveguide (11, 12) having a positive thermal optical path length expansion affixes the optical waveguide to at least two points of a material having a negative thermal expansion and comprises the material of a composite of a resin matrix having embedded therein fibers having a negative thermal expansion coefficient and optionally fibers having a positive thermal expansion coefficient, whereby to provide the negative thermal expansion.

Abstract: In accordance with the invention, a wavelength stable optical source comprises at least one adjustable wavelength optical source, a multipath Mach-Zehnder interferometer (MMZI) for receiving a signal from the adjustable source and providing a primary output and one or more secondary outputs, and a feedback arrangement responsive to the outputs for adjusting the wavelength source. Photodetectors coupled to the primary output and one or more of the secondary outputs provide feedback information for maintaining wavelength stability.

Abstract: The present invention provides a photonic local oscillator signal generator. The generator includes a plurality of waveguides fabricated in a single substrate. The waveguides are fabricated with a lateral separation that enables an evanescent tail of an optical mode field generated in one waveguide to overlap with an evanescent tail of an optical mode field generated in an adjacent waveguide. The overlap of the evanescent tails produce cross-coupling between the laser light generated in the adjacent waveguides. The generator uses a common pumping element to pump laser cavities of both of the waveguides. The use of a common pumping element and the cross-coupling produces phase locking between the laser light generated in the plurality of waveguides. As a result of the phase locking, mutual optical coherence between the laser light is achieved. The mutual optical coherence provides an interference signal upon photodetection.

Abstract: Phase masks which can be used to make both linear and curved gratings of single or multiple submicron pitches, with or without any abrupt quarter-wavelength shifts (or gradually varying finer phase shifts) simultaneously on the wafer/substrate. The phase masks are made using direct write electron or ion-beam lithography of two times the required submicron pitches of linear and curved gratings on commercially available &pgr; phase-shifting material on a quartz substrate and wet or dry etching of the &pgr; phase-shifting material. The phase masks can be used in connection with making multi-wavelength laser diode chips. The laser diodes have a ridge structure with metal shoulders on either side of the ridge. The laser diode chip, with different wavelength lasers, is bonded and interfaced to a novel microwave substrate that allows for high signal-to-noise ratio and low crosstalk. The substrate is packaged in a low loss rugged housing for WDM applications.

Abstract: A monolithically integrated light source and frequency discriminator has a section in which a single frequency optical signal is produced and a section in which the frequency is sensed. The output of the optical discriminator is connected to a controller for stabilizing the output frequency of the light source.

Abstract: Provided are complex optical material that trivalent ytterbium ion is codoped into single crystalline, poly crystalline or amorphous material containing tetravalent chromium ion or trivalent vanadium ion as an active medium, and a using method of the material. In application of the material to solid-state lasers, optical fiber amplifiers and the likes, when excitation occurs in the 980 nm wavelength band in which absorption strongly occurs at the ytterbium ion with avoiding the wavelength range of 600˜800 nm in which the excited-state absorption occurs at the chromium ion, the energy is transferred from the ytterbium ion to the chromium ion to emit fluorescence in the range of 1200˜1600 nm wavelength. Accordingly, the present invention is to solve the problem of the excitation efficiency decrease of the tetravalent chromium ion due to the excited-state absorption and to enhance the fluorescence emission intensity.

Abstract: A semiconductor laser with single longitudinal mode includes active region(s) and phase shift region(s). An optical cavity such as a passive waveguide extends through the active region(s) and the phase shift region(s). A diffraction grating in the active region(s) has a refractive index. An active layer in the active regions is located between the diffraction grating and the passive waveguide. The phase shift region(s) have a refractive index difference &Dgr;n with respect to the index of the active region(s). The phase shift region(s) are located adjacent to and/or between the active region(s). An optical mode is shifted in the phase shift region. An eletro-optical circuit tunes a lasing wavelength of the laser by varying &Dgr;n. The electro-optical circuit reverse or forward biases a tuning junction to change the refractive index difference &Dgr;n using field effects or carrier effects.

Abstract: A laser oscillation device, which has an optical fiber where laser ion is doped; an excitation emission element that generates one laser beam including multiple wavelength components by exciting the laser ion in the optical fiber by light emission; a total reflection element that is located at one end of the optical fiber and reflects uniformly laser beam with multiple wavelengths; a separation optical element that is located at another end of the optical fiber and separates laser beam into beams with multiple wavelengths; and a plurality of partial reflection element that reflect separately laser beams with multiple wavelengths separated by the separation optical element.

Abstract: In a laser, the optical cavity includes a pair of spaced-apart electrode plates which are RF excited transversely and a pair of substantially identical spherical mirrors having a radius of curvature, spacing and alignment selected to cause a beam within the cavity to make a plurality of round trips and mirror encounters along a set of off-axis paths, before returning, in phase, to its starting point. The multiple traversals of the cavity result in a long effective gain path equivalent to the number of round trips times the mirror spacing. The plurality of off-axis traversals of the laser beam trace out a plane around the gain region before exiting through the aperture in the first spherical mirror, permitting an effective utilization of the wide excitation region defined by the electrodes. In a CO2 laser, the electrodes are separated by an electrode spacing such that the modes perpendicular to the electrodes are waveguide in nature to form a stable cavity resonator.

Abstract: A compression-tuned bragg grating includes a tunable optical element 20,600 which includes either an optical fiber 10 having at least one Bragg grating 12 impressed therein encased within and fused to at least a portion of a glass capillary tube 20or a large diameter waveguide grating 600 having a core and a wide cladding. Light 14 is incident on the grating 12 and light 16 is reflected at a reflection wavelength &lgr;1. The tunable element 20,600 is axially compressed which causes a shift in the reflection wavelength of the grating 12 without buckling the element. The shape of the element may be other geometries (e.g., a “dogbone” shape) and/or more than one grating or pair of gratings may be used and more than one fiber 10 or core 612 may be used. At least a portion of the element may be doped between a pair of gratings 150,152, to form a compression-tuned laser or the grating 12 or gratings 150,152 may be constructed as a tunable DFB laser.

Abstract: A single mode surface emitting laser and its manufacturing method are provided. The surface emitting laser which has a characteristic of single transverse mode radiation in the broad region using reflectivity distribution of a reflector layer with an antiguide clad is provided.

Abstract: An integrated optic device for optical signals comprises substrate carrying a surface acousto-optic tunable filter utilized to provide signals indicative of the wavelength of the optical signals, and a tunable filter controllable via a processor such that the tunable filter passes only optical signals at a predetermined wavelength.

Abstract: The invention relates to an external cavity, continuously tunable monomode laser source, comprising, in a resonant cavity, resonating at the emission wavelength &lgr;e, a retroreflecting wavelength dispersing device, arranged to produce a selectivity curve with a peak 80 s. According to the invention, additional fine-control means, enable, from the approximate continuous tunability position, to monitor the deviation &lgr;e-&lgr;s during the variation of the emission wavelength ke while preventing this deviation from reaching one of the limits causing mode hopping. Such a configuration enables to avoid imperfections usually associated with mechanical adjustment and to guarantee continuity of the wavelength variation and to compensate for the latter as long as its fluctuations remain smaller than approx. &Dgr;&lgr;e/2 where &Dgr;&lgr;e is the distance between two successive resonance modes of the cavity.

Abstract: Optical detection apparatus comprises a solid state laser having an intracavity optical waveguide that supports a lasing filament and operates in one of two states: (1) in a first state, the filament is fixed in one of two orientations, and (2) in a second state, the filament may be induced to switch or oscillate between the two orientations, or it may be suppressed altogether. At least one feature is located on the output facet off-center with respect to the waveguide cross-section in order to provide a preferred orientation for the filament. In one embodiment, a single feature is located off-center and optical radiation of one intensity is injected through the facet feature, thereby causing the laser to operate in one of its states, whereas injected radiation of another intensity causes the laser to operate in the other of its states. The injected radiation may be radiation emitted by the laser that is reflected by an object (e.g.

Abstract: The array is highly suitable for producing a spacially wide output “beam” (comprising a number of individual beams). It suffers less from problems of hotspots and filamentation since each tapered laser supports a limited number of modes, or even a single mode. Therefore it produces a semiconductor laser which is especially suitable for pumping of other lasers and to be used in materials processing.

Abstract: A tunable laser incorporating an N1×N2 chirped waveguide grating router that has N1N2 wavelengths, accessible in a digitally rapid manner, and using only N1+N2+1 semiconductor optical amplifiers. Through the use of chirp, free-spectral range of the router can be significantly less than the channel span. The exemplary laser has N1=5, N2=8, a channel spacing of 100 GHz, and the router free-spectral range is only 20 channels.

Abstract: A multichannel laser is based on an interleaved chirped waveguide grating router. An interferometric modulator is incorporated inside a laser cavity by means of a waveguide grating router and enables independent modulation of any of the wavelengths of the multichannel laser. The interferometric modulator operates independently of the wavelength selection elements of the waveguide grating router used to select the wavelengths of the multichannel laser.

Abstract: A compression-tuned bragg grating includes a tunable optical element 20,600 which includes either an optical fiber 10 having at least one Bragg grating 12 impressed therein encased within and fused to at least a portion of a glass capillary tube 20 or a large diameter waveguide grating 600 having a core and a wide cladding. Light 14 is incident on the grating 12 and light 16 is reflected at a reflection wavelength &lgr;1. The tunable element 20,600 is axially compressed which causes a shift in the reflection wavelength of the grating 12 without buckling the element. The shape of the element may be other geometries (e.g., a “dogbone” shape) and/or more than one grating or pair of gratings may be used and more than one fiber 10 or core 612 may be used. At least a portion of the element may be doped between a pair of gratings 150,152, to form a compression-tuned laser or the grating 12 orgratings 150,152 may be constructed as a tunable DFB laser.

Abstract: Apparatus for providing a laser source optically coupled to an optical waveguide, such as an optical fiber, having a reflective grating positioned from the output facet of the laser source a distance equal to or greater than the coherence length of the laser source providing a portion of reflective feedback into the laser source optical cavity to maintain wavelength operation of the laser source in spite of changes in the laser operating temperature or drive current based upon coherence collapse in the laser operation. In cases where the fiber grating is positioned in the fiber within the coherence length of the laser source, intermittent coherence collapse, as opposed to continuous coherence collapse, is unavoidable. In cases where such a laser source is a pumping source for a solid state gain medium, such as an optical amplifier or laser having an active gain element, e.g.

Abstract: A laser system and method for beam enhancement utilizes shaped electrodes or one or more shaped lasing media, including crystal media, to prescribe the operational transverse modes of the laser. The electrodes and shaped lasing media are shaped with respect to the transverse mode or modes to be selected for operational use. In some embodiments shaping is done according to the selected transverse modes for operation so that at least a designated percentage of the total operational power of the beam is made up of the selected transverse modes. The designated percentage of total operational power of the selected transverse modes can be 90% of the total power of the beam, but in other more relaxed cases can be 85% and in other more stringent cases are 95% of the beam. In some embodiments, the electrodes or lasing media are so shaped that the theoretical fundamental transverse mode is the only selected transverse operational mode. Some embodiments utilize folded resonators.

Abstract: A laser with a heat transfer system and method of making the same using electrodes. The heat transfer system draws heat from the electrodes which have internal electrode surfaces adjacent to a lasing medium of the laser. Cooling of the electrodes helps to maintain proper operating temperature for the lasing medium. The heat transfer system utilizes thermally conductive material positioned between external surfaces of the electrodes and internal surfaces of a housing that contains the electrodes and the lasing medium. Since the thermally conductive material adds capacitance to the laser system, inductance may be added for compensation depending upon the amount of thermally conductive material used.

Abstract: A laser assembly system and method uses an electrode assembly and flexible housing to reduce manufacturing costs and complexity. The flexible housing also helps to insure uniform contact with the housing and electrically insulating material between the housing and electrodes. The uniform contact in turn assists in maintaining a uniform electric field in the discharge area of the laser, which affects laser performance, and assists in maintaining efficient cooling of the electrodes and the lasing medium. The electrode assembly is pre-assembled before insertion into the laser housing, which reduces adverse effects of anomalies of housing construction and helps to reduce the complexity and cost of manufacturing of the laser. The electrode assembly includes first and second electrodes that are separated by spacers made out of an electrically insulating material such as ceramic.

Abstract: A clamping device for an RF excited laser is provided which reduces stress on ceramic components and also is less expensive than existing clamping devices. The RF excited laser lacking an electrode over the waveguide channel intersection regions. Ceramic covers are provided over a portion of these channel intersection regions to reduce plasma build up. Increased power is achieved by adding a fourth channel to a conventional waveguide to form a ring resonator. The optical component mount uses radial compressive forces to hold the optical component to a post, thereby preventing the face of the optical component from being distorted. Mirror mounts are also configured to allow more mirrors to be mounted at each end of the laser. The waveguide channel of the RF excited laser having a U-shaped cross section and an aspect ratio grater than one-to-one, which improves laser performance. A beam redirection device allows the laser head to serve as a mounting surface for other optical components.

Abstract: A compound planar waveguide comprising multiple confinement structures that provides independent containment of pump and laser radiation. The waveguide may be formed of multiple layers of laser-active and laser-inactive materials to provide step changes in refractive index. The planar waveguide may include a central laserable core layer substantially sandwiched by at least two non-laserable cladding layers to provide an interface between the inner surfaces of the cladding layers and the gain medium core to define a first waveguide by virtue of an index of refraction discontinuity for containing developed laser radiation, and wherein the outer surfaces of the cladding layers define a second waveguide by virtue of an index of refraction discontinuity for containing pump radiation within the waveguide. The second waveguide may be also defined by an interface formed between the cladding layers and additional non-laserable external layers which sandwich the cladding layers.

Abstract: A new class of vertical-cavity lasers (VCLs) is disclosed. Conventional VCLs contain an active region enclosed by Bragg-mirror stacks of 30-100 quarter-wave layers. The new VCLs can be fabricated without Bragg mirrors by replacing them with efficient diffractive (guided-mode resonance (GMR)) mirrors with much fewer layers, for example, two or three layers. This application provides optical power flow across and along the VCL gain region, thereby greatly increasing the laser efficiency and reducing the threshold mirror reflectance needed for lasing, relative to conventional VCLs. Theoretical and experimental results show that GMR mirrors exhibit high reflectance (theoretically, 100%; experimentally, in excess of 90%) in a narrow spectral band with well-defined polarization states. When incorporated in VCLs, the GMR mirrors yield single-mode, narrow-line, highly-polarized output light. The GMR-VCL is independent of any particular material system.

Abstract: A laser to produce pulses of light having predetermined spectral shapes, comprising a waveguide, an optical pump source, a gain medium to produce seed radiation, and a modulator and an array of Bragg gratings to modify the properties of the seed radiation. Once generated by the gain medium, the seed radiation propagates in the waveguide where it is first pulsed by the modulator. The resulting pulses are then selectively reflected by the Bragg gratings, which separates different spectral components of the reflected beam. This reflected beam then travels back to the modulator, which is timed to let only the desired spectral components go through. In this manner the laser is self-seeded and allows spectrum and wavelength selection from pulse to pulse.

Abstract: The performance of an RF excited gas laser having a discharge region with a generally curvilinear orthogonal cross-section, the shorter of the two dimensions of the discharge region cross-section being the spacing between non-conductive sidewalls which collisionally cool the discharge and are rotatable for guiding laser light, is enhanced by excitation field shaping. The field shaping includes use of a non-conductive member disposed between a high voltage field establishing electrode and a sidewall of the discharge region.

Abstract: An external cavity mirror for use in a semiconductor laser, the external cavity mirror comprising a waveguide formed on a substrate of highly electro-optic material, and including electrically-operated means for determining the reflectance attributes of the external cavity mirror.

Abstract: A compact multiwavelength laser arrangement includes a reflective waveguide grating combined with two arrays of reflecting waveguide elements located in separate focal regions formed by the grating. The laser uses a folded imaging arrangement with nonoverlapping focal regions that eliminates unwanted resonances of previous reflective arrangements. The laser's advantages over existing transmissive laser arrangements include reduced size, faster response time, and increased number of wavelengths.

Abstract: A harmonic generator laser system which features a distributed Bragg reflector (DBR) or distributed feedback (DFB) tunable diode laser coupled to a quasi-phase matched (QPM) waveguide of optically nonlinear material. Tuning of the DBR laser may be achieved either thermally or via current injection, or both, halving the wavelength of a red laser into the visible blue spectral band. Thermal tuning may provide a coarse tuning adjustment, while injected current may provide fine tuning accessible to a user. Separately or in combination with current tuning, a modulation signal may be applied to the DBR laser for achieving an intensity modulated or a pulsed output. In another embodiment, modulation may be achieved by frequency modulation of the laser. A very compact tunable blue laser is formed. In yet another embodiment a double clad fiber amplifier is disposed between the tunable laser and the waveguide.

Abstract: A short wavelength laser includes a light source having a fundamental generating portion which emits fundamental wave and a wavelength convertor which converts the fundamental wave to its second harmonic. A light amplifier amplifies the second harmonic.

Abstract: An improved wavelength tunable transmitter comprises a waveguide grating router coupled to a truncated Mach-Zehnder interferometric modulator. Light from the second order Brillouin zones of a waveguide grating router having substantially the same phase are captured and coupled to first and second transmission paths comprising the truncated Mach-Zehnder interferometer, the transmission paths then being altered relative to each other and recombined to produce a modulated output signal. With this configuration, a compact tunable transmitter is provided exhibiting bandwidth and chirp control features comparable with those of a traditional Mach-Zehnder interferometer.

Abstract: The present invention relates to a white pulse source that produces spectrally shaped white pulses of a constant optical output power over a wide wavelength range. The white pulse source includes a pump pulse source for generating pump pulses with a center wavelength .lambda.0 and a waveguided nonlinear optical medium with a length L. The waveguided nonlinear optical medium is characterized by two properties: the first property is that chromatic dispersion D(.lambda.0,z) at the center wavelength of pump pulses in ps/nm/km is positive at an input end of said waveguided nonlinear optical medium, where z=0, and decreases towards an output end. The second property is that said chromatic dispersion D(.lambda., z) has a maximum value D(.lambda.p(z), z) at a peak wavelength .lambda.p(z) within a range of propagation distance given by L1.ltoreq.z.ltoreq.L where 0.ltoreq.L1<L, and that said chromatic dispersion D(.lambda., z) has two zero-dispersion wavelengths, .lambda.1(z) and .lambda.2(z), where D(.lambda.

Abstract: In accordance with the invention, a tunable laser uses magnets to apply mechanical strain on fiber Bragg grating reflectors or laser cavities in order to induce a change in lasing wavelength. The strain can be tensile or compressive. The tunable laser comprises a laser cavity including a laser material for emitting light in response to stimulating light and two end reflectors one or more of which can be a Bragg grating. In preferred embodiments, latchable programmable magnets vary the grating periodicity and/or cavity length in a controlled, accurate manner so as to achieve desired tuning of the laser over a broad range of wavelengths. The latchable magnets hold the wavelength in the shifted position without the need for sustained power.

Abstract: A method of and apparatus for measuring chirp passes an input modulated optical signal through a Waveguide Grating Router (WGR) and processes the signals from adjacent WGR output ports in an oscilloscope, to obtain the real-time dynamic chirp measurements of the modulated optical signal.

Abstract: A free electron laser amplifier provides a scalloping annular electron beam that interacts with the axial electric field of a TM.sub.0n mode. A waveguide defines an axial centerline and, a solenoid arranged about the waveguide produces an axial constant magnetic field within the waveguide. An electron beam source outputs a annular electron beam that interacts with the axial magnetic field to have an equilibrium radius and a ripple radius component having a variable radius with a ripple period along the axial centerline. An rf source outputs an axial electric field that propagates within the waveguide coaxial with the electron beam and has a radial mode that interacts at the electron beam at the equilibrium radius component of the electron beam.

Abstract: A nonlinearly chirped fiber grating for achieving tunable dispersion compensation, chirp reduction in directly modulated diode lasers, and optical pulse manipulation. A dynamical dispersion compensation mechanism can be implemented in a fiber communication system based on such a nonlinearly chirped fiber grating.