Abstract: A method for producing controllable light pulses includes the following steps: providing a heterojunction bipolar transistor structure including collector, base, and emitter regions of semiconductor materials; providing an optical resonant cavity enclosing at least a portion of the transistor structure; and coupling electrical signals with respect to the collector, base, and emitter regions, to switch back and forth between a stimulated emission mode that produces output laser pulses and a spontaneous emission mode. In a form of the method, the electrical signals include an AC excitation signal, and part of each excitation signal cycle is operative to produce stimulated emission, and another part of each excitation signal cycle is operative to produce spontaneous emission.

Abstract: A laser system, such as a master oscillator/power amplifier system, comprises a gain medium and a stimulated Brillouin scattering SBS mirror system. The SBS mirror system includes an in situ filtered SBS medium that comprises a compound having a small negative non-linear index of refraction, such as a perfluoro compound. An SBS relay telescope having a telescope focal point includes a baffle at the telescope focal point which blocks off angle beams. A beam splitter is placed between the SBS mirror system and the SBS relay telescope, directing a fraction of the beam to an alternate beam path for an alignment fiducial. The SBS mirror system has a collimated SBS cell and a focused SBS cell. An adjustable attenuator is placed between the collimated SBS cell and the focused SBS cell, by which pulse width of the reflected beam can be adjusted.

Abstract: A laser system with a solid state laser medium, having a broad oscillation spectrum with improved absorption efficiency of the laser medium for excitation light. The system includes: a resonator; a solid state laser medium, disposed in the resonator, having optical anisotropy; and an excitation unit for inputting excitation light to the solid state laser medium. The oscillation light is linear polarization light polarized in the direction substantially parallel to a first crystal axis of the solid state laser medium, and the excitation unit linearly polarizes the excitation light, and inputs to the solid state laser medium, with the polarization direction of the excitation light in a direction crossing the first crystal axis. In the solid state laser medium, an absorption coefficient for the excitation light in the polarization direction thereof is greater than an absorption coefficient for the excitation light in the first axis direction.

Abstract: A device for emission of laser radiation includes at least one semiconductor laser having a resonator and a pumped active zone disposed within the resonator. The zone is subdivided into at least two spatially separated active zones by free-radiation regions without lateral wave guidance. Preferably, the laser is at least two semiconductor lasers disposed in series, a row, or a line, each having an antireflection coating on at least one side. The lasers have outer mirror elements at an end of the lasers disposed in series and the outer mirror elements form the resonator. A laser configuration includes two opposite semiconductor lasers from which a fundamental mode is in each case imaged into the active zone of the opposite semiconductor laser. The laser configuration has an emerging laser beam with little divergence.

Abstract: An optical pulses emitter includes a first and a second Fabry-Perot laser diodes. The first and second laser diodes have a first and second working optical wavelength band respectively, and the first and second working wavelength bands has at least an overlapped wavelength band. The emitter also includes a signal source in connection with the first laser diode such that a plurality of optical pulses over the first working optical wavelength band is generated and an optical filter for filtering the optical pulses so as to output a plurality of optical pulses primarily of a desired optical wavelength, which falls into the overlapped wavelength band. The emitter further includes an optical amplifier along an optical path between the first and second Fabry-Perot laser diodes for amplifying the optical signals passing therethrough.

Abstract: A laser controlling method can generate laser of stable laser pulses, and eliminate useless time from a machining procedure. The method uses a gain medium and a Q-switch, and emits exciting light to the gain medium, thereby setting the Q-switch in a continuous oscillation mode, and prepares a given Q-switch pause time before a laser pulse is generated. When the continuous oscillation is kept going longer than a given time, the control method sets a Q-switch pause time for obtaining a first laser pulse to be different from a Q-switch pause time for obtaining a second laser pulse and onward.

Abstract: This invention discloses a fiber Chirped Pulse Amplification (CPA) laser system. The system includes a fiber mode-locking oscillator for generating a seed laser. The laser system further includes a stretching stage for stretching the seed laser for projecting to an Yb doped amplifier. The Yb doped amplifier is implemented for taking advantage of a self phase modulation (SPM) to broaden a spectrum whereby an amplification of the laser pulse is without narrowing down the spectrum. The amplifier has a gain spectrum corresponding to a broaden spectrum by taking advantage of the SPM in the amplifier. The amplifier is further connected to an output fiber having a predefined length with a predefined level of SPM for broadening a spectrum.

Abstract: A source of pulses of coherent radiation at a wavelength of approximately 1 ?m, comprises a pump source for producing pump light; a laser cavity comprising an Yb3+-doped gain medium arranged to receive the pump light, the laser cavity being modelocked to generate laser pulses at a defined repetition rate; a pulse detector arranged to generate a pulse selection signal indicative of the repetition rate; a pulse selector arranged to reduce the repetition rate of the laser pulses responsive to the pulse selection signal from the pulse detector by passing only selected ones of the laser pulses; and at least one optical amplifier for amplifying the laser pulses of reduced repetition rate. The at least one optical amplifier can be configured for chirped or parabolic pulse amplification.

Abstract: Optical systems configured for both changing the length of a laser pulse and operating as an optical isolator are disclosed. In some embodiments, optical isolation is achieve contemporaneously with laser pulse expansion or compression by using a grating based compressor or expander as one of the polarization elements of the optical isolator. In some embodiments, optical isolation is achieved contemporaneously with laser pulse expansion or compression by using a mode converter and a Bragg fiber as one of the polarization elements of the optical isolator. In some embodiments, a sub-wavelength polarizer including magnetic garnet is included in the optical isolator. In some embodiments, an optical isolator is disposed between a final pulse amplifier and a target material in order to prevent light resulting from the delivery of an amplified laser pulse to the target material from traveling back to the final pulse amplifier.

Abstract: A system for measuring the energy of an ultra-short pulse in a laser beam includes a half-wave plate for orienting the polarization of the beam. A polarizing beam splitter is used to reflect a portion of each pulse of the beam and a remainder of the beam is transmitted toward a target. Energy in the reflected portion is measured by a laser energy meter (“LEM”) to determine the energy in the remainder of the beam. An output signal from the LEM is used to obtain an error signal that can then be used to rotate the half-wave plate to control the energy level in the remainder of the beam. In an alternate embodiment, a fixed-ratio beam splitter and a second LEM are used to measure and control the energy in the remainder of the laser beam.

Abstract: An optical pulse train generator (2) for use in the transmission of high speed optical data in a return-to-zero (RZ) signalling format is described.

Abstract: An apparatus and method generating an optical pulse of picosecond class (having a high duty ratio), which accurately and stably operates at an arbitrary repetition frequency, has a high OSNR, and is not restricted by an RF modulation frequency, are provided. New modulation spectrum components are generated by performing phase modulation for light output from a single wavelength laser light source with an optical phase modulator. The phases of the modulation spectrum components are aligned by a phase adjuster, so that a pulse wave in a time domain is generated.

Abstract: A laser apparatus includes a laser element that emits the laser beam. A detector detects the laser beam emitted from the laser element. A controller controls the laser element such that the laser beam is oscillated subject to multiple conditions, such as the emission frequency and the energy of the laser beam, when the laser element is in a ready state, based on the detection results. In the ready state, the laser beam is not emitted from the apparatus onto a subject. Closely monitoring the oscillated beam in the ready state allows the precise beam desired to be emitted in an operational mode. The apparatus is useful for fabricating semiconductor devices.

Abstract: There is provided a nonlinear optical crystal which is presented by the formula: K2Al2B2O7. This nonlinear optical crystal is a vacuum ultraviolet light generating nonlinear optical crystal which is easy to grow and of high practical use. There are also provided a wavelength conversion method using this crystal, and an element and a wavelength conversion apparatus for use in the method.

Abstract: The present invention contemplates a simplified laser oscillator-amplifier system for deep UV generation. The simplified system employs same type of gain media in both the oscillator and the amplifier and utilizes a single pump pulse split to pump both the oscillator and the amplifier. A short cavity oscillator is operated near lasing threshold to produce a seed pulse with a narrow spectral bandwidth and long pulse duration. A short cavity amplifier is Q-switched to amplify the seed pulse to produce a single short pulse with good energy extraction efficiency. The amplifier is simply a short cavity, Q-switched laser. Short pulse is obtained with short cavity length and high gain of the amplifier. Consequently, the simplified laser oscillator-amplifier system can accommodate a long pump pulse to produce a nanosecond pulse suitable for deep UV laser generation.

Abstract: In a device for reducing the peak power of a pulsed laser light source, in particular for a projection exposure system, there is arranged in the beam path (1) at least one beam splitter apparatus (3, 4) by means of which a detour line (5 or 11) is produced, via reflecting components (6, 7, 8 or 12, 13, 14) for at least one partial beam (1b) with subsequent recombination at a beam recombining element (9 or 15) with the other partial beam or beams (1b or 10b) to form a total beam.

Abstract: A laser source provides a pulse that is subdivided and replicated into subpulses by a delay structure having a plurality of steps. Each of the subpulses is delayed by one of the plurality of steps and the amount that each subpulse is delayed is different than the others with respect to the pulse. The amount of each delay, and the consequent time delay produced, is greater than the duration of the pulse, which minimizes overlap between adjacent subpulses. The pulse may be transmitted through the delay structure or it may be reflected from the delay structure. Repetition rates of up to hundreds of THz or greater are achieved, and the system and method may be used in Time Division Multiplexing Systems. Information may be transmitted and carried by the subpulses by appropriate modulation techniques.

Abstract: A source of pulses of coherent radiation at a wavelength of approximately 1 ?m, comprises a pump source for producing pump light, a laser cavity comprising an Yb3+-doped gain medium arranged to receive the pump light, the laser cavity being modelocked to generate laser pulses at a defined repetition rate; a pulse detector arranged to generate a pulse selection signal indicative of the repetition rate; a pulse selector arranged to reduce the repetition rate of the laser pulses responsive to the pulse selection signal from the pulse detector by passing only selected ones of the laser pulses; and at least one optical amplifier for amplifying the laser pulses of reduced repetition rate. The at least one optical amplifier can be configured for chirped or parabolic pulse amplification.

Abstract: The invention is directed to a method for the energy stabilization of a gas discharge-pumped radiation source that is operated in defined pulse sequences, particularly for suppression of overshooting and undershooting of excimer lasers and EUV radiation sources in burst operation. It is the object of the invention to find a novel possibility for the stabilization of the energy emission of a gas discharge-pumped radiation source that is operated in defined pulse sequences (bursts) which makes it possible to take into account a temporary behavior of the radiation source at the beginning of every burst without repeated recalibration of the energy-voltage curve.

Abstract: In a gas laser machining apparatus based on a pulse laser oscillation, a mis-pulse-preventing pulse, viz., a preparatory pulse component whose energy is below the threshold value of a laser oscillation, is located prior to a first pulse of discharging power pulses.

Abstract: An optical phase detector comprising coupling means for receiving two optical inputs and for producing two combined optical outputs, means for detecting the two combined optical outputs and producing two corresponding electrical signals, and means for measuring the difference between the two electrical signals and generating an output difference signal which may be used to provide an indication of the phase difference between the two optical inputs. The optical phase detector comprises a voltage-tuneable electro-optic phase modulator for modulating the phase of an optical input to the optical phase detector to provide a linearized response. In this arrangement the output difference signal may be maintained at a constant level by varying the voltage applied to the electro-optic phase modulator, the applied voltage providing an indication of the phase difference between the two optical inputs. Applications include frequency discriminators, various sensors, and a laser stabilization apparatus.

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: Feedback timing control equipment and process for an injection seeded modular gas discharge laser. A preferred embodiment is a system capable of producing high quality pulsed laser beams at pulse rates of about 4,000 Hz or greater and at pulse energies of about 5 to 10 mJ or greater for integrated outputs of about 20 to 40 Watts or greater. The feedback timing control is programmed to permit in some circumstances discharges timed so that no significant laser energy is output from the system. Use of this technique permits burst mode operation in which the first discharge of a burst is a no-output discharge so that timing parameters for each of the two chambers can be monitored before the first laser output pulse of the burst. Two separate discharge chambers are provided, one of which is a part of a master oscillator producing a very narrow band seed beam which is amplified in the second discharge chamber.

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 image display apparatus includes a plurality of light emission sources, a drive circuit for pulse-driving the plurality of light emission sources in order in a predetermined period, a moving reflecting mirror for swinging in order in an incidence direction of light from each of the light emission sources in response to the pulse driving timing of each of the light emission sources and reflecting light beams from the light emission sources in order approximately in the same direction, and a combining optical system for guiding the light reflected by the moving reflecting mirror into a light valve.

Abstract: A pulsed solid-state thin-disk laser comprises an optical resonator and a solid-state laser gain medium placed inside the optical resonator. The laser gain medium is in the shape of a thin plate or layer with two end faces, the extension of the end faces being greater than a thickness of said plate or layer measured in a direction perpendicular to one of the end faces. One of the end faces comprises a cooling surface, via which the laser gain medium is cooled. A pumping source is provided for exciting the laser gain medium to emit electromagnetic radiation. The thin-disk laser further comprises means for passive mode locking placed inside the optical resonator. The mode-locking means are preferably a semiconductor saturable absorber mirror (SESAM). The laser offers a high average power, a good beam quality, short pulses and a high efficiency. Problems such as thermal lensing, Q-switching instabilities and damages of the mode-locking means are avoided. Moreover, the output power of the laser is scalable, i.e.

Abstract: An asymmetric Fabry-Perot modulator is disclosed having an adjustable resonant cavity length. A preferred embodiment of the invention includes an asymmetric Fabry-Perot modulator having a first reflector adjustably mounted to another portion of the modulator containing a second reflector. The length of the resonant cavity is adjusted by microelectomechanically changing the distance from the first reflector to the second reflector. In turn, this change of the resonant cavity length may tune the modulator to an optimal wavelength corresponding to the electro-absorptance material in the modulator.

Abstract: The present invention relates to a wavelength-swept laser and a method for generating laser output. The wavelength-swept pulse laser according to one aspect of the present invention uses spontaneous mode-locking to produce a pulse output with the center wavelength continuously varying with time. On the contrary, the wavelength-swept laser according to another aspect of the present invention suppresses mode-locking to produce continuous output by tuning the filter frequency change speed to the frequency shift speed of the frequency shifter. The lasers of the present invention are applicable to optical sensing or WDM optical communication.

Abstract: A nonlinear polarization amplifier stage includes a gain medium operable, to receive a multiple wavelength optical signal. The amplifier stage also includes a pump assembly operable to generate at least one pump wavelength for introduction to the gain medium. The amplifier stage further includes a coupler operable to introduce the at least one pump wavelength to the gain medium to facilitate amplification of at least a portion of the multiple wavelength optical signal through nonlinear polarization. In one particular embodiment, at least a wavelength or an intensity of the at least one pump wavelength is manipulated to affect the shape of a gain curve associated with the multiple wavelength optical signal in the amplifier stage.

Abstract: A Laser arrangement (1) comprising a pump unit (2) containing a pumped laser crystal (3), and means, such as a saturable absorber (15), for passive mode-locking, wherein two separate, alternatively switchable resonator arms (11, 12) are provided, one resonator arm (11) of which, which is active in a pulse forming phase (21), comprises the saturable absorber (15), whereas the other resonator arm (12), which is active in an amplifying phase (22), is free from components that introduce losses.

Abstract: A semiconductor self-pulsating laser diode (1) comprises a wave guiding layer (2) sandwiched between lower and upper cladding layers (4, 5). A current blocking layer (8) defining a slot (10) through which pumping current is directed through the laser diode between upper and lower contact plates (5, 6) defines an active wave guiding region (15). The current blocking layer (8) is shaped by the formation of longitudinally extending recesses (12) for defining the active wave guiding region (15) such that a central pulse light generating region (17) is formed surrounded by an outer light propagating region (18). As the laser diode is continuously pumped, an effective step change in refractive index between the wave guiding layer (2) and the outer light propagating region (18) is formed, and the carrier density and refractive index profiles across the active wave guiding region (15) vary as each light pulse cycle progresses.

Abstract: An optoelectric module includes a cylindrical ferrule defining an optical axis and having a first end constructed to receive an optical fiber aligned along the optical axis. A TO-can is positioned within the ferrule and has a first end with an optical element therein for conducting light therethrough. A base is affixed to the second end of the TO-can and to the second end of the ferrule. A laser is mounted within the TO-can so that light generated by the laser is directed through the optical element along the optical axis. A laser driver is mounted on the base and electrically connected to the laser. External connections to the laser driver are completed by either electrical traces on a surface of the base, vias through the base, or flexible leads mounted on the base.

Abstract: The present invention contemplates an integrated oscillator-amplifier system for deep UV generation. The system employs a long cavity oscillator to lengthen the pulse build-up time and to control the pulse spectral bandwidth. Meanwhile the system employs a short cavity amplifier to shorten the energy extraction time to produce a single short pulse with good energy extraction efficiency. The system further integrates the oscillator and the amplifier by inserting the amplifier cavity inside the oscillator cavity via a mirror of low reflectivity. As a result, the integrated system has a long build-up time to generate a seed pulse in the long cavity oscillator and has a short energy extraction time to generate a short amplified single pulse in the short cavity. Consequently, the integrated system can accommodate a relatively long pump pulse to produce a single short amplified pulse suitable for deep UV laser generation.

Abstract: A harmonic Q switch laser device and its control method for obtaining a stable laser pulse while protecting a nonlinear optical crystal used for a wavelength conversion are presented. In this laser device, in a pause period of a laser train, a Q switch which is turned on makes the laser oscillates spuriously and continuously, and prevents a gain from accumulating in a gain medium Before a generation of a laser pulse, the Q switch is turned off for a specified period to raise the laser gain, so that a pulse of a specified magnitude is generated from the first shot when turning on the Q switch.

Abstract: An apparatus and method for flexibly and precisely varying temporal placement and duration of pulses, within a train of high speed, high power optical pulses. The invention includes optics adapted for focusing on a layer of an information storage media. An optical pulse generator is coupled with the layer through the optics for generating a train of optical pulses, wherein each pulse has a respective temporal placement within the train and has a respective pulse duration. The respective pulse duration of each pulse is controlled by an amount of an analog duration control voltage, in accordance with a WRITE STRATEGY, which is based on a physical property of the layer of the information storage media. Similarly the respective temporal placement of each pulse is controlled by an amount of an analog temporal placement control voltage, in accordance with the WRITE STRATEGY.

Abstract: In a gas laser machining apparatus based on a pulse laser oscillation, a mis-pulse-preventing pulse, viz., a preparatory pulse component whose energy is below the threshold value of a laser oscillation, is located prior to a first pulse of discharging power pulses.

Abstract: A method and gas replenishment algorithm for excimer and molecular fluorine lasers is based on parameters upon which gas aging more closely depends than pulse count, such as input energy to the electrical discharge, and also preferably time. A burst control method and algorithm includes measuring the energies of initial pulses of a first burst occurring after a long burst break, calculating values of input voltages for the initial pulses that would bring output energies of the individual laser pulses or groups of pulses to substantially the same values, and applying the calculated voltages in a subsequent first burst after a long burst break to achieve substantially same predetermined output energy values for the pulses or groups of pulses. Similar operations may be performed for one or more subsequent bursts following the first burst.

Abstract: A method and apparatus are provided for increasing the energy of chirped laser pulses to an output in the range 0.001 to over 10 millijoules at a repetition rate 0.010 to 100 kHz by using a two stage optical parametric amplifier utilizing a bulk nonlinear crystal wherein the pump and signal beam size can be independently adjusted in each stage.

Abstract: A rapidly oscillating laser light source is produced that exhibits extended pulse duration having a substantially uniform amplified output. A pulsed beam of laser light having a given wavelength, frequency, duration and intensity is produced such that the pulse shape is controlled. The pulsed beam is amplified using a fiber amplifier which exhibits inherent changes in amplifier gain at the frequencies of interest. The fiber amplifier is continuously pumped. A feedback signal is provided with the amplified pulse characteristics and is used to adjust the pulse shape of the pulsed beam of laser light before amplifying, such that the intensity is changed over the pulse duration to generate a substantially uniform amplified output during each pulse.

Abstract: A wavelength stabilizing unit includes a wavelength filter 31 and an optical detector 4, which are mounted on a substrate 71, and housed in a casing 91. The optical detector 4 includes a first photoelectric conversion element 5, which directly receives an emitted light from an end portion (emitting point 58) of an optical fiber 14 guided into the casing 91 and converts it into an electric signal A, and a second photoelectric conversion element 6, which receives light passed through the wavelength filter 31 and converts it into an electric signal B. The electric signals A and B are supplied to an operation circuit 8. The wavelength filter 31 has side faces, which are machined such that they do not cross a straight line connecting the emitting point 58 and an edge of an incident surface 311 of the wavelength filter.

Abstract: A system and method for reducing peak power of a laser pulse and reducing speckle contrast of a single pulse comprises a plurality of beamsplitters, mirrors and delay elements oriented to split and delay a pulse or pulses transmitted from a light emitting device. The design provides the ability to readily divide the pulse into multiple pulses by delaying the components relative to one another. Reduction of speckle contrast entails using the same or similar components to the power reduction design, reoriented to orient received energy such that the angles between the optical paths are altered such that the split or divided light energy components strike the target at different angles or different positions. An alternate embodiment for reducing speckle contrast is disclosed wherein a single pulse is passed in an angular orientation through a grating to create a delayed portion of the pulse relative to the leading edge of the pulse.

Abstract: The present invention provides a modular high repetition rate ultraviolet gas discharge laser light source with a beam delivery to a production line machine. The system includes an enclosed and purged beam path with beam pointing control for delivery the laser beam to a desired location such as the entrance port of the production line machine. Preferred embodiments include equipment for beam attenuation, equipment for automatic feedback beam alignment and equipment for accurate optics module positioning at installation and during maintenance. In preferred embodiments, the production line machine is a lithography machine and two separate discharge chambers are provided, one of which is a part of a master oscillator producing a very narrow band seed beam which is amplified in the second discharge chamber. This MOPA system is capable of output pulse energies approximately double the comparable single chamber laser system with greatly improved beam quality.

Abstract: In a method and apparatus for synchronizing the output of two passively modelocked pulsed lasers, the output of each laser is sampled and delivered to two photodiodes, one for each laser. The output of the each photodiode is converted to a train of digital pulses having the pulse repetition frequency of each laser. The digital pulses are processed in a digital phase detector that generates from the digital pulses a first analog voltage representative of the phase difference at the photodiodes between corresponding pulses in each train. This analog voltage is summed with a second analog voltage representative of a desired phase relationship of the laser pulses at a target location remote from the photodiodes. The sum of the analog voltages provides an error signal that commands a device to adjust the length of the resonator of one of the lasers. When the error signal is minimized, pulses from each laser have the same repetition frequency and have the desired phase relationship at the target.

Abstract: A diode pumped solid state laser/OPO system widely tunable in mid infrared spectrum for infrared matrix assisted laser desorption/ionization (MALDI) mass spectroscopy is disclosed. Up to a few tens of milli-Joule, short pulse, tunable near infrared laser pulse is generated from an all solid state laser at a high pulse repetition rate up to one kHz. The tunable near-infrared laser pumps a Quasi-Phase Matching (QPM) OPO system to further shift the wavelength to the mid-IR range and to broaden the tuning range to as much as 3 &mgr;m to effectively generate a widely tunable spectral output. The wide range tuning of the infrared output is accomplished by a narrow range tuning of the pump laser. The pump laser output is generated by a diode pumped tunable solid state laser module using either a Yb:YAG crystal or any other efficient tunable laser crystals. The wavelength range (2-5 &mgr;m) covered by the solid state laser system is optimum for MALDI applications.

Abstract: An intracavity frequency converted, Q-switched laser and method for operating such laser to obtain high output power in secondary pulses at a converted frequency. The secondary pulses are generated by a intracavity frequency conversion element from primary pulses at the fundamental wavelength. In accordance with the invention, after the primary and secondary pulses are generated the Q-switch is turned back on before the gain is fully depleted in the generation of the primary pulse. In particular, the Q-switch is turned back on such that a certain amount of energy of the primary pulse is retained in the laser, but late enough so that a majority of the secondary pulse is out-coupled from the laser. The Q-switched laser is well-suited for use at pulse repetition rates larger than 1/&tgr;, where &tgr; is an upper state lifetime (fluorescence lifetime) of the laser. Specifically, the laser can be operated at repetition rates of 10 kHz and higher, e.g.

Abstract: A high power fiber laser/amplifier is comprised of a multi-mode rare-earth-doped helical core disposed within a cylindrical inner cladding. The inner cladding is enclosed within an outer cladding whereby the core effectively produces single-mode operation with a circularly polarized near-diffraction-limited beam quality output when pump radiation is injected into the inner cladding.

Abstract: A burst (50) of ultrashort laser pulses (52) is employed to sever a conductive link (22) in a nonthermal manner and offers a wider processing window, eliminates undesirable HAZ effects, and achieves superior severed link quality. The duration of the burst (50) is preferably in the range of 10 ns to 500 ns; and the pulse width of each laser pulse (52) within the burst (50) is generally shorter than 25 ps, preferably shorter than or equal to 10 ps, and most preferably about 10 ps to 100 fs or shorter. The burst (50) can be treated as a single “pulse” by conventional laser positioning systems (62) to perform on-the-fly link removal without stopping whenever the laser system (60) fires a burst (50) of laser pulses (52) at each link (22). Conventional wavelengths or their harmonics can be employed.

Abstract: A multiple-wavelength ultrashort-pulse laser system includes a laser generator producing ultrashort pulses at a fixed wavelength, and at least one and preferably a plurality of wavelength-conversion channels. Preferably, a fiber laser system is used for generating single-wavelength, ultrashort pulses. An optical split switch matrix directs the pulses from the laser generator into at least one of the wavelength conversion channels. An optical combining switch matrix is disposed downstream of the wavelength-conversion channels and combines outputs from separate wavelength-conversion channels into a single output channel. Preferably, waveguides formed in a ferroelectric substrate by titanium indiffusion (TI) and/or proton exchange (PE) form the wavelength-conversion channels and the splitting and combining matrices. Use of the waveguide allows efficient optical parametric generation to occur in the wavelength-conversion channels at pulse energies achievable with a mode-locked laser source.

Abstract: An optical configuration to illuminate an etalon in a laser wavemeter with a minimum level of light intensity. The system includes optical components to direct a portion of the laser output beam representing the entire cross section of the beam, through an etalon positioned in an etalon housing and onto a photodetector. A first lens condenses the size of the beam sample, and a second lens re-collimates the beam which then passes into the etalon housing, ensuring that all of the spatial components of the beam are adequately sampled. A diffractive diffusing element is incorporated into the optical path. In a preferred embodiment, the diffractive diffusing element is placed within the etalon housing between said plano-concave lens and the etalon. In another preferred embodiment, the diffusing element is located up stream but outside the housing in the optical path.

Abstract: A method and circuit is disclosed for providing a control signal to a laser cavity controller. The cavity has two completely reflective surfaces. A long lived laser medium stores energy within the cavity. A computer generated waveform generated from enough values to appear substantially smooth after being amplified is provided to a control circuit having a Pockels cell or a Bragg cell. By controlling the amplitude of the computer generated waveform, the output pulse of the laser cavity is controlled.