Abstract: A pulse detection laser is provided. The pulse detection laser includes a single frequency oscillator, a continuous pre-amplifier, and a pulsed amplifier. The single frequency oscillator generates a seed laser beam and is optically coupled to the continuous preamplifier. The continuous pre-amplifier amplifies the seed laser to produce an intermediate power laser beam. A pulsed amplifier optically coupled to the continuous pre-amplifier receives the intermediate power laser beam and amplifies the intermediate power laser beam to produce a pulse detection laser beam. One task of this pulse detection laser is to illuminate ultrasonic displacements. Light from the laser is scattered, collected, and analyzed with an interferometer to demodulate the ultrasonic displacements caused by the return echoes of the ultrasound at the surface of the part.

Abstract: A femtosecond laser based laser processing system having a femtosecond laser, frequency conversion optics, beam manipulation optics, target motion control, processing chamber, diagnostic systems and system control modules. The femtosecond laser based laser processing system allows for the utilization of the unique heat control in micromachining, and the system has greater output beam stability, continuously variable repetition rate and unique temporal beam shaping capabilities.

Abstract: A short pulse laser arrangement with, preferably, passive mode-locking, comprising a resonator containing a laser crystal and several mirrors, one of which forms a pump beam coupling-in mirror and one of which forms a laser beam out-coupling mirror, and a multiple reflexion telescope enlarging the resonator length, the resonator in operation having a positive averaged dispersion over a wavelength range concerned; the adjustment of the positive averaged dispersion of the resonator is effected by means of the mirrors of the resonator, at least a few of which are designed as dispersive mirrors.

Abstract: A projection system that includes a singe light modulation device and a plurality of light sources of different wavelengths. Each wavelength of light is incident on the light modulation device at a spatially distinct location and a temporally distinct time. The use of a scanning mirror allows the projection system to sequentially form, in full-color, each of the columns or rows of an image. The projection system is characterized by the reduction of color separation or the rainbow effect due to the rendering of each column or row in full color.

Abstract: In a pulse generator of very high resolution phase and/or intensity profiles, an active mode-locking laser source (1) emits a first train of optical pulses according to a determined period (To), which is intensity-modulated pulse-by-pulse by a modulator (2). The modulated pulses are transmitted to an optical loop (3) via a coupler (4). The optical length of the optical loop is slightly different from the period (To) of the source. The modulated pulses are transmitted to input B of the coupler. The optical loop connects output D to input A of the coupler. This coupler is commanded such that, according to a first command (k=0), it transmits the light received on its two inputs A, B towards output d, and according to a second command (K=1), it transmits the light received on its input (A) towards output (C).

Abstract: A method of controlling an optical output of a laser diode includes applying a bipolar current pulse to the laser diode, thereby substantially suppressing the emission tail of the optical output of the laser diode. A device for generating sub-nanosecond intense optical pulses includes a driver unit operative to generate a plurality of bipolar current pulses, and a semiconductor laser diode driven by the bipolar current pulses and operative to emit the intense optical pulses each of which has a substantially suppressed or completely eliminated emission tail.

Abstract: A method is disclosed for varying a pulse repetition rate of a passively q-switched laser while maintaining other characteristics of the laser radiation. The laser is optically pumped with a sequence of pump pulses which includes alterations between non-zero power levels and is characterized by two adjustable parameters. By simultaneously changing the adjustable parameters, the pulse repetition rate of the laser can be changed while maintaining the laser pulse energy, divergence of the pulsed laser radiation, and optical spectrum of the pulsed laser radiation at constant levels. In one embodiment, the sequence of pump pulses includes pump power offset which magnitude and/or duration is adjusted when the laser repetition rate is changed.

Abstract: An all-fiber optical pulse compression arrangement comprises a concatenated arrangement of a section of input fiber (e.g., a single mode fiber), a graded-index (GRIN) fiber lens and a section of pulse-compressing fiber (e.g., LMA fiber). The GRIN fiber lens is used to provide mode matching between the input fiber (supporting the propagation of chirped optical pulses) and the pulse-compressing fiber, with efficient pulse compression occurring along the length of the LMA fiber. The dispersion and length of the LMA fiber section are selected to provide the desired degree of pulse compression; for example, capable of reconstituting a femtosecond pulse as is used in supercontinuum generation systems.

Abstract: Disclosed herein is a laser driving apparatus, including: a driving unit adapted to current drive a laser device with a current value in accordance with a level of a signal supplied thereto; and an emission light waveform correction unit adapted to receive supply of a pulsed reference signal and generate, based on a correction timing pulse interlocked with a rising edge and/or a falling edge of a pulse, a correction signal having a level different from that of the reference signal and then supply the correction signal to the driving unit so that the shape of the emission light waveform of the laser device becomes close to that of a rectangular wave.

Abstract: Output optical energy pulses including relatively high energy magnitudes at the beginning of each pulse are disclosed. As a result of the relatively high energy magnitudes which lead each pulse, the leading edge of each pulse includes a relatively large slope. This slope is preferably greater than or equal to 5. Additionally, the full-width half-max value of the output optical energy distributions are between 0.025 and 250 microseconds and, more preferably, are about 70 microseconds. A flashlamp is used to drive the laser system, and a current is used to drive the flashlamp. A flashlamp current generating circuit includes a solid core inductor which has an inductance of 50 microhenries and a capacitor which has a capacitance of 50 microfarads.

Abstract: A fiber Chirped Pulse Amplification (CPA) laser system includes a fiber mode-locking oscillator for generating a laser for projecting to a fiber stretcher for stretching a pulse width of the laser wherein the stretcher further comprising a Photonic Bandgap (PBG) fiber having a lower nonlinearity and an abnormal dispersion than a solid core fiber for connecting and transmitting a laser from the stretcher to a multistage amplifier for amplifying the laser into an output laser whereby a separate compressor is not required.

Abstract: A novel polarization maintaining optical fiber, which can be used as a high-power polarization maintaining fiber laser or amplifier, is described. Insensitivity of the polarization state to external fiber bending and temperature changes is accomplished by minimizing polarization mode-coupling via reducing stresses inside the fiber core via increasing the fiber diameter. Alternatively, polarization mode-coupling can be minimized by an optimization of the fiber coating to minimize stresses at the interface between the fiber and the coating. As a result insensitivity to polarization mode-coupling is obtained at greatly reduced values of birefringence compared to small-diameter fibers. The fiber is of significant use in any application where polarization stability is important, and will be useful in telecommunications applications in particular for reducing polarization mode dispersion. An implementation in a parabolic pulse-producing fiber laser is also described as one specific high power example.

Abstract: An optical pulse stretcher and a mathematical algorithm for the detailed calculation of its design and performance is disclosed. The optical pulse stretcher has a plurality of optical cavities, having multiple optical reflectors such that an optical path length in each of the optical cavities is different. The optical pulse stretcher also has a plurality of beam splitters, each of which intercepts a portion of an input optical beam and diverts the portion into one of the plurality of optical cavities. The input optical beam is stretched and a power of an output beam is reduced after passing through the optical pulse stretcher and the placement of the plurality of optical cavities and beam splitters is optimized through a model that takes into account optical beam divergence and alignment in the pluralities of the optical cavities.

Abstract: A programmable laser pulse combines electrical modulation of the pulse frequency and optical modulation of the pulse shape to form laser pulses of prescribed pulse shapes. A prescribed pulse shape features high peak power and low average power. The laser system disclosed also allows for power-scaling and nonlinear conversions to other (shorter or longer) wavelengths. The system provides an economical reliable alternative to using a laser source with high repetition rates to achieve shaped pulses at a variety of wavelengths. The combinatorial scheme disclosed is inherently more efficient than existing subtractive methods.

Abstract: A pulsed laser comprises an oscillator and amplifier. An attenuator and/or pre-compressor may be disposed between the oscillator and amplifier to improve performance and possibly the quality of pulses output from the laser. Such pre-compression may be implemented with spectral filters and/or dispersive elements between the oscillator and amplifier. The pulsed laser may have a modular design comprising modular devices that may have Telcordia-graded quality and reliability. Fiber pigtails extending from the device modules can be spliced together to form laser system. In one embodiment, a laser system operating at approximately 1050 nm comprises an oscillator having a spectral bandwidth of approximately 19 nm. This oscillator signal can be manipulated to generate a pulse having a width below approximately 90 fs.

Abstract: Systems and methods for pre-correcting accumulated optical nonlinear phase error in a shaped optical pulse derived from a continuous wave laser signal are provided. A continuous wave laser signal is received. A pulse signal is received. A shaped optical pulse is generated from the continuous wave laser signal upon being driven by the pulse signal. A pulse intensity level to be applied to the phase of the shaped optical pulse is received. A phase correcting signal is generated based on the pulse intensity level. Application of the phase correcting signal to the shaped optical pulse is time-synchronized and the phase correcting signal is applied to the shaped optical pulse to generate a pre-corrected shaped optical pulse.

Abstract: This invention discloses a method to control laser dynamics in a gain-switched fiber laser so as to generate stable, clean pulses in an all-fiber format. The gain-switched fiber laser is suitable as a standalone laser source, and as a pump source for harmonic generation and an optical-parametric-oscillator.

Abstract: The invention describes classes of robust fiber laser systems usable as pulse sources for Nd: or Yb: based regenerative amplifiers intended for industrial settings. The invention modifies adapts and incorporates several recent advances in FCPA systems to use as the input source for this new class of regenerative amplifier.

Abstract: A novel polarization maintaining optical fiber, which can be used as a high-power polarization maintaining fiber laser or amplifier, is described. Insensitivity of the polarization state to external fiber bending and temperature changes is accomplished by minimizing polarization mode-coupling via reducing stresses inside the fiber core via increasing the fiber diameter. Alternatively, polarization mode-coupling can be minimized by an optimization of the fiber coating to minimize stresses at the interface between the fiber and the coating. As a result insensitivity to polarization mode-coupling is obtained at greatly reduced values of birefringence compared to small-diameter fibers. The fiber is of significant use in any application where polarization stability is important, and will be useful in telecommunications applications in particular for reducing polarization mode dispersion. An implementation in a parabolic pulse-producing fiber laser is also described as one specific high power example.

Abstract: In a cavity-dumped, repetitively-pulsed, solid-state laser cavity dumping is protracted over a predetermined time longer than a round-trip time of the resonator of the laser. The cavity dumping is effected by a Pockels cell optical switch. During a dumping period a voltage applied to the Pockels cell falls in a predetermined time. Varying the voltage fall-time varies the duration of pulses provided by the laser, independent of the pulse-repetition frequency.

Abstract: In a detection method for undesired double- or multiple-pulse states in an ultra-short-pulse laser system operated in the soliton regime and intended for generating femtosecond or picosecond pulses, comprising an amplifying laser medium for producing a laser emission, a laser resonator having at least one resonator mirror and a pump source, a first signal ? proportional to the pulse power P(t) or pulse energy averaged over the resonator cycle is measured for the laser emission. A second signal ? proportional to the square of the pulse power P(t), averaged over the resonator cycle, is measured for the laser emission, and the occurrence of a double- or multiple-pulse state is detected on the basis of a comparison of the measured signals ? and ?.

Abstract: A high-power laser system includes a laser master oscillator, a plurality of fiber laser amplifiers producing intermediate output beamlets, a diffractive optical element for combining the intermediate beamlets into a combined output beam, and one or more error controllers for minimizing errors related to beam combination that may degrade the quality of the combined output beam. A piston error controller uses phase modulation to tag each non-reference intermediate beamlet with a unique dither signal harmonically unrelated to those used for the other beamlets. For each intermediate beamlet, the associated piston error is recovered using a synchronous detector, and an error control signal proportional to the piston error is supplied to a phase modulator to control the piston error for that beamlet. A tilt error controller uses amplitude modulation based on Hadamard code words to tag each non-reference intermediate beamlet with a unique code sequence orthogonal to those used for the other beamlets.

Abstract: A wavelength tunable laser module for DWDM is used, in which a single electroabsorption modulator integrated laser is mounted and an oscillation wavelength is made tunable by temperature control. Driving conditions of a laser and a modulator are determined such that they have approximately the same modulation and transmission characteristics in a temperature control range. Such an electroabsorption modulator integrated laser is used and the driving conditions are incorporated, thereby a small, inexpensive wavelength tunable optical transmitter can be provided.

Abstract: A method and device are provided for generating bursts of sub-pulses, preferably in the picosecond range. Seed pulses are first generated, and then phase modulated to spread their spectral profile to several time-dependent spectral components. The phase modulated seed pulses are then spectrally filtered to remove spectral components and retain only selected ones, creating gaps in the amplitude profile of the seed pulses which therefore form bursts of sub-pulses. Various parameters such as the modulation amplitude, the modulation frequency, the spectral characteristics of the filters and the overall amplitude of the seed pulses may be controlled to provide a great versatility and adaptability.

Abstract: A high-power laser system includes a laser master oscillator, a plurality of fiber laser amplifiers producing intermediate output beamlets, a diffractive optical element for combining the intermediate beamlets into a combined output beam, and one or more error controllers for minimizing errors related to beam combination that may degrade the quality of the combined output beam. A piston error controller uses phase modulation to tag each non-reference intermediate beamlet with a unique dither signal harmonically unrelated to those used for the other beamlets. For each intermediate beamlet, the associated piston error is recovered using a synchronous detector, and an error control signal proportional to the piston error is supplied to a phase modulator to control the piston error for that beamlet. A tilt error controller uses amplitude modulation based on Hadamard code words to tag each non-reference intermediate beamlet with a unique code sequence orthogonal to those used for the other beamlets.

Abstract: Methods and devices for generating stable, tunable and intense output light pulses are provided. A primary beam of light pulses is used to form a filament in an interaction zone. A secondary bean of light pulses is superposed with the filament and interacts therewith to generate the output light pulses. The parameters of the primary and secondary beams in the interaction zone can be controlled to obtain targeted optical characteristics of the output pulses. Multiple secondary beams may also be used.

Abstract: A tunable pulsed laser source comprising a seed source adapted to generate a seed signal and an optical circulator. The optical circulator includes a first port coupled to the seed source, a second port, and a third port. The laser source also includes an amplitude modulator characterized by a first side and a second side. The first side is coupled to the second port of the optical circulator. The laser source further includes a first optical amplifier characterized by an input end and a reflective end including a spectral-domain reflectance filter. The input end is coupled to the second side of the amplitude modulator. Moreover, the laser source includes a second optical amplifier coupled to the third port of the optical circulator.

Abstract: An rf pulse compressor has a single high Q cavity resonator fed by a four port hybrid coupler which is connected to the resonator at coupling ports located at the intersection of two of the resonator's orthogonal axes with the resonator cavity walls. The hybrid coupler divides pulse power from an rf pulse power source and excites two space and phase orthogonal modes in the single cavity, the stored energy of which aids in producing compressed pulses at the output of the hybrid. On-axis perturbations in the cavity walls can be used to lock the orthogonal orientation of the modes excited in the cavity.

Abstract: A laser source assembly (10) for providing an assembly output beam (12) includes a first MIR laser source (352A), a second MIR laser source (352B), and a beam combiner (244). The first MIR laser source (352A) emits a first MIR beam (356A) that is in the MIR range and the second MIR laser source (352B) emits a second MIR beam (356B) that is in the MIR range. Further, the beam combiner (244) spatially combines the first MIR beam (356A) and the second MIR beam (356B) to provide the assembly output beam (12). With this design, a plurality MIR laser sources (352A) (352B) can be packaged in a portable, common module, each of the MIR laser sources (352A) (352B) generates a narrow linewidth, accurately settable MIR beam (356A) (356B), and the MIR beams (356A) (356B) are combined to create a multiple watt assembly output beam (12) having the desired power. The beam combiner (244) can includes a combiner lens (364) and an output optical fiber (366).

Abstract: A method for controlling operation of a transistor includes the following steps: providing a bipolar transistor having emitter, base and collector regions; applying electrical signals to the transistor to produce light emission from the transistor; effecting photon-assisted tunneling of carriers in the transistor with self-generated photons of the light emission, and controlling operation of the transistor by controlling the photon-assisted tunneling.

Abstract: Apparatus and method for generating controlled-linewidth laser-seed-signals for high-powered fiber-laser amplifier systems. In some embodiments, the natural chirp (frequency change of laser light over a short start-up time) of a DBR laser diode when driven by pulsed current is used to broaden the linewidth of the laser output, while adjusting the peak current and/or the pulse duration to obtain the desired linewidth.

Abstract: Apparatus for stabilizing carrier-envelope phase (CEP) of laser pulse generated by mode locked pulsed laser based on direct locking method includes laser oscillator, interferometer, detector and double feedback circuit. The laser oscillator includes the mode locked pulsed laser generating the laser pulse. The interferometer generates laser pulses having first and second frequency components from the laser pulse generated by the mode locked pulsed laser to generate first and second interference signals that substantially correspond to each other in time domain and space domain. The detector receives the first and second interference signals to output third and fourth interference signals by inverting phase of the second interference signal. The double feedback circuit controls the laser oscillator so that the CEP of the laser pulse generated by the mode locked pulsed laser has substantially constant value with respect to time using CEP signal obtained from the third and fourth interference signals.

Abstract: The performance of a laser scanner is optimized in the field by automatically determining appropriate laser parameters for the scan location. A laser control system uses information such as the environmental temperature to select an appropriate range of start points for various laser parameters, such as pump temperature and laser currents. Test pulses over that range can be used to determine optimal operating parameters.

Abstract: A method for producing an optical output, including the following steps: providing first and second electrical signals; providing a bipolar light-emitting transistor device that includes collector, base, and emitter regions; providing a collector electrode coupled with the collector region and an emitter electrode coupled with the emitter region, and coupling electrical potentials with respect to the collector and emitter electrodes; providing an optical coupling in optical communication with the base region; providing first and second base electrodes coupled with the base region; and coupling the first and second electrical signals with the first and second base electrodes, respectively, to produce an optical output emitted from the base region and coupled into the optical coupling, the optical output being a function of the first and second electrical signals.

Abstract: Provided is a hybrid laser diode. The hybrid laser diode includes: a silicon layer constituting a slab waveguide; and a compound semiconductor layer disposed on the silicon layer to constitute a channel waveguide.

Abstract: Various embodiments described herein relate to a laser source for producing a pulsed laser beam comprising a plurality of ultrashort optical pulses having a variable repetition rate. In one embodiment, the laser source comprises a fiber oscillator, which outputs optical pulses and a pulse stretcher disposed to receive the optical pulses. The optical pulses have an optical pulse width. The pulse stretcher has dispersion that increases the optical pulse width yielding stretched optical pulses. The laser source further comprises a fiber amplifier disposed to receive the stretched optical pulses. The fiber optical amplifier has gain so as to amplify the stretched optical pulses. The laser source includes an automatically adjustable grating compressor having dispersion that reduces the optical pulse width. The grating compressor automatically adjusts this dispersion for different repetition rates.

Abstract: A driver laser for EUV light source apparatus which driver laser simultaneously achieves short-pulsing and multi-line oscillation. The driver laser includes: a short-pulse multi-line oscillated CO2 laser oscillator having a device that shortens width of pulses included in a laser beam to be output and a device that suppresses amplitude of an oscillation spectrum exhibiting an energy peak value; and at least one amplifier that inputs the laser beam output from the short-pulse multi-line oscillated CO2 laser oscillator and amplifies the input laser beam to output the amplified laser beam.

Abstract: Phase matching high harmonic generation (HHG) uses a single, long duration non-collinear modulating pulse intersecting the driving pulse. A femtosecond driving pulse is focused into an HHG medium (such as a noble gas) to cause high-harmonic generation (HHG), for example in the X-ray region of the spectrum, via electrons separating from and recombining with gas atoms. A non-collinear pulse intersects the driving pulse within the gas, and modulates the field seen by the electrons while separated from their atoms. The modulating pulse is low power and long duration, and its frequency and amplitude is chosen to improve HHG phase matching by increasing the areas of constructive interference between the driving pulse and the HHG, relative to the areas of destructive interference.

Abstract: Various embodiments include modelocked fiber laser resonators that may be coupled with optical amplifiers. An isolator may separate the laser resonator from the amplifier, although certain embodiments exclude such an isolator. A reflective optical element on one end of the resonator having a relatively low reflectivity may be employed to couple light from the laser resonator to the amplifier. Enhanced pulse-width control may be provided with concatenated sections of both polarization-maintaining and non-polarization-maintaining fibers. Apodized fiber Bragg gratings and integrated fiber polarizers may be also be included in the laser cavity to assist in linearly polarizing the output of the cavity. Very short pulses with a large optical bandwidth may be obtained by matching the dispersion value of the fiber Bragg grating to the inverse of the dispersion of the intra-cavity fiber. Frequency comb sources may be constructed from such modelocked fiber oscillators.

Abstract: Methods and apparatus for maintaining a quality of a Raman medium in a Raman conversion cell. In various examples, a flow velocity of the Raman medium is tailored based on a spatial nonuniformity of heat deposition resulting from the Raman conversion in the cell. In particular, in one example, the flow velocity of the Raman medium may be tailored to be higher where the heat deposition/temperature rise is larger and smaller elsewhere in the cell. This type of flow velocity profile reduces the overall required volumetric flow of the Raman medium in the cell without significantly affecting a quality of the Raman medium.

Abstract: A device for generating light pulses that are separated in terms of time has a light source that emits a sequence of light pulses. A regulation signal is formed within a regulation circuit from a cycle signal and the light pulse sequence of the light sources via a phase detector. The regulation circuit includes a regulator that generates a setting signal that influences the repeat frequency of the light pulse sequence of the light source.

Abstract: A laser provides a cavity with complementary wavelength-dependent delay elements to provide the same optical length but time-staggered light paths for different colors. This provides the ability to individually control multiple narrow bands of colors each in a separate time division window.

Abstract: The present invention is directed to methods and apparatuses for performing temporal scanning using ultra-short pulsewidth lasers in which only minimal (micro-scale) mechanical movement is required. The invention also relates to methods for obtaining high-accuracy timing calibration, on the order of femtoseconds. A dual laser system is disclosed in which the cavity of one or more of the lasers is dithered, by using a piezoelectric element. A Fabry-Perot etalon is used to generate a sequence of timing pulses used in conjunction with a laser beam produced by the laser having the dithered laser cavity. A correlator correlates a laser pulse from one of the lasers with the sequence of timing pulses to produce a calibrated time scale.

Abstract: A system for real-time linewidth reduction in an optical source includes a laser device comprising a back facet, wherein the laser device receives a modulated input current and generates an optical output signal; an etalon device disposed adjacent to the back facet of the laser device, wherein the etalon device receives an optical feedback output signal from the back facet of the laser device, and wherein the etalon device monitors the optical feedback output signal for changes in frequency and, if they exist, generates an optical correction output signal; a photo-detector device disposed adjacent to the etalon device, wherein the photo-detector device receives the optical feedback and correction output signals, and wherein the photo-detector device converts the optical feedback and correction output signals into an electrical signal; and a feedback correction loop coupled to the photo-detector device, wherein the feedback correction loop receives the electrical signal from the photo-detector device and gener

Abstract: A light source device includes a light source for emitting a laser beam, a power supply drive circuit for pulse-driving the laser beam, a wavelength conversion element for converting a wavelength of a laser beam into a predetermined wavelength, a photodetector for detecting an intensity of the laser beam emitted from the wavelength conversion element, and a control section that controls a drive condition of the laser beam emitted from the wavelength conversion element based on the intensity detected by the photodetector, wherein the control section includes an optimization setting section that, in response to the intensity of the photodetector in a present pulse drive condition being outside a predetermined range, controls a drive condition of the laser beam to extract an optimum pulse drive condition, and sets the extracted optimum pulse drive condition to the drive condition of the laser beam instead of the present pulse drive condition, and the optimization setting section, in extracting the optimum drive

Abstract: A laser system using ultrashort laser pulses is provided. In another aspect of the present invention, the system includes a laser, pulse shaper and detection device. A further aspect of the present invention employs a femtosecond laser and binary pulse shaping (BPS). Still another aspect of the present invention uses a laser beam pulse, a pulse shaper and a SHG crystal.

Abstract: A high power electric pulse generator includes a charge storage device, a high voltage source for charging the charge storage device, a first photoconductor element connected to the reference potential and to the storage device, a second photoconductor element connected to the storage device and to a useful load, a first light source for delivering a pulse of light to the first photoconductor, a second light source for delivering a pulse of light to the second photoconductor and a synchronization device for synchronizing the emission delay between the first light source and the second light source. The first photoconductor and the second photoconductor are passive semiconductor elements with a linear regime forming photosensitive switches, with the first and second photoconductors being doped silicon photoconductors.

Abstract: Techniques and devices to stabilize a passively mode-locked laser against the timing jitter by using a feedback control signal based on a signal component at a high harmonic frequency of the laser pulse repetition frequency in the laser output to control the optical path length of the laser resonator.

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: Method of processing, e.g., laser annealing, objects such as semiconductor devices with pulsed lasers with high production yield and high reproducibility so as to obtain good characteristics stably. The pulse width of the irradiated pulse beam is set to more than 30 nsec to stabilize the processing. To achieve a pulse width exceeding 30 nsec, plural lasers are connected in series or in parallel and excited successively.