Abstract: The pulsed laser control system comprises a plurality of controllers (2) through (6) for controlling devices (21) through (30) constituting the pulsed laser apparatus (1); parallel communication lines (P1) to (P4) for parallel connection of the plurality of controllers (2) through (6); an Ethernet (S) for serial connection of the plurality of controllers (2) through (6); parallel communication line (PP) for parallel connection between the external apparatus (10) and the main controller (2); and an Ethernet (SS) for serial connection between the external apparatus (10) and the main controller (2); wherein the parallel communication lines (P1) to (P4) and (PP) transmit signals for which realtime performance is required. With this construction, even if design changes are frequently made to a pulsed laser apparatus, the changes can be made easily and with little expansion space. Moreover, management of the devices constituting the pulsed laser apparatus can be easily performed.

Abstract: Embodiments of methods and an apparatus for generating a specific laser radiation for production of high quality laser-induced damage images are disclosed. One or more embodiments of the invention comprise a method and system for generating the specific laser radiation by serial combination of both generation regimes: a Q-switched mode and a free-running mode. According to the invention the combination of both regimes is produced during a single flash of a pulsed pumping source by successive switching a loss level in a resonant cavity. Desirable ratio of a Q-switched pulse energy and a free-running mode pulse energy is achieved by adjusting the time delay of Q-switching and the threshold level in the resonant cavity. A Q-switched pulse creates laser-induced breakdown and a free-running pulse maintains plasma of the breakdown as long as it is necessary to create a damage of a desirable size.

Abstract: A laser modulating device is provided with a monitoring system that outputs a detection voltage signal corresponding to the output power, a minimum output level setting system that outputs a minimum level voltage signal, a modulating voltage signal generating system, a first adder that outputs a reference voltage signal corresponding to a sum of the minimum level voltage signal and the modulating voltage signal, a comparing system that outputs a driving voltage signal corresponding to a difference between the reference voltage signal and the detection voltage signal, a first V/I converting system that converts the driving voltage signal to a first driving current, the first driving current being supplied to the laser diode, a second V/I converting system, and a circuit that directly supplies the modulating voltage signal from the modulating voltage signal generating system to the second voltage to current converting system, the second voltage to current converting system converting the modulating voltage sign

Abstract: A device for encoding data into high speed optical train includes N data encoding branches, each having a dual-mode laser, generating at the beat frequency f, and an external modulator. Each dual mode laser includes a laser structure having two sections formed on the same substrate which simultaneously operate at different longitudinal modes. Each section has a complex coupled (gain-coupled or loss-coupled) grating which is formed by deep etching through the multi-quantum well structure, ensuring no substantial interaction between lasers. The sections have common active medium and shared optical path and provide mutual light injection into each other. Signals from the branches are put through a variable delay line, introducing phase shifts between the signals, and compressed in the optical compressor. Thus, N short pulse optical trains are formed.

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 laser device which repeats a cycle of burst mode operation in each of which continuous oscillating operations for continuously pulsatively oscillating laser light by a prescribed number of times and stopping operations for stopping the pulsative oscillation for a prescribed pausing time are alternately executed, controls the power supply voltage of the laser device so that each output energy of the pulsative oscillation can become coincide with a target value, finds the difference between the output voltage of each pulse and the target value at every pulse and, for a pulse for which the difference exceeds tolerance limits, corrects and updates the power supply voltage value stored in the voltage data table means corresponding to the pulse number of the pulse and the measured oscillation pausing time by using the control gain of a control gain setting means set in the block corresponding to the pulse number and the measured oscillation pausing time and the difference, so as to always make the pulse energy of

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 semiconductor device manufacturing method includes the steps of providing a projection exposure apparatus, exposing a wafer by using the projection exposure apparatus, the exposing step including projecting a circuit pattern onto the wafer through the projection optical system using light from a first laser, and developing the exposed wafer. Before the providing step, an optical performance of the projection optical system is measured by producing an interference fringe, bearing information related to aberration of the projection optical system, by use of a harmonic of a second laser having a coherency higher than that of the first laser, and then by analyzing the interference fringe. A wavelength of the light from the first laser is registered with that of the harmonic of the second laser.

Abstract: When an IGBT turns on, a current from a laser power supply unit is supplied via a switching element to an excitation lamp of a laser oscillation unit so that the excitation lamp lights to oscillatorily output a laser beam. A switching control unit uses as a main feedback signal a measured-value-of-laser-output signal from a laser output measurement unit and uses as a sub-feedback signal for correction an AC component of a lamp measured-value-of-power signal from a power computing circuit or of a measured-value-of-lamp-current signal from a current measuring circuit. The switching control unit compares the feedback signals with a reference signal having a desired pulse waveform from a CPU to obtain a comparison error. The switching control unit then generates a switching control signal, PWM so as to nullify the comparison error and provides a switching control of the IGBT via a drive circuit in response to the switching control signal.

Abstract: The gas laser oscillator of the invention comprises a discharge tube, a pair of electrodes disposed at both ends thereof, a direct-current high voltage power source for applying a direct-current high voltage in pulse form to the pair of electrodes, an output control device for controlling the direct-current high voltage power source, a fully reflective mirror provided at one end of the outside of the pair of electrodes, a partially reflective mirror disposed at the other end of the outside of the pair of electrodes, and an absorber disposed outside of the partially reflective mirror. In thus constituted gas laser oscillator, the output control device controls to apply a same direct-current voltage as during processing between the pair of electrodes also on standby while the absorber is closed.

Abstract: A simmer circuit 18 comprises a power supply unit 54 for the supply of a simmer current Is to an excitation lamp 22 and a control unit 56 for the control of the current value of the simmer current Is. In the control unit 56, a current detection signal Vs from a current sensor, e.g., a Hall CT 70 attached to the power supply unit 54 is fed via a buffer amplifier 72 for impedance conversion to a non-inversion input terminal of an operational amplifier 82 for signal amplification. The amplification factor &mgr; of the operational amplifier 82 differs depending on which one is selected from three switches 84, 86 and 88. A CPU 38 selects the switch 84 when switching the simmer current Is to 0.3 A for “low speed zone”, selects the switch 86 when switching to 2 A for “medium speed zone” and switches 88 when switching to 5 A for “high speed zone”.

Abstract: A diagnostic system is disclosed for monitoring the operation of an excimer laser. A typical excimer laser generates a light pulse in response to a trigger signal. The trigger signal propagates from an external source through a number of electrical modules to the gas discharge. In accordance with the subject invention, outputs from each of the various modules are supplied to digital counters. When the laser is operating properly, each counter will record a single count for each trigger signal. When a fault occurs, the number of counts counted by the counter connected to the faulty module will not match the number of trigger signals. The service engineer can use the information in the counters to help identify which module in the trigger chain is experiencing problems.

Abstract: An oscillator for isolating a transverse electromagnetic (TEM) zero—zero mode pulsed laser beam includes a laser pumping diode that is mounted on a base to induce a multi-mode laser beam from a lasing medium. As initially induced, the multi-mode laser beam is directed along a path and is characterized by a beating signal which has a frequency that is based on amplitude variations of laser pulses in the multi-mode laser beam. Electronics detect this beating signal and generates a responsive error signal. With closed loop control, the error signal is used to advance a straightedge toward the path of the multi-mode laser beam to remove transverse modes from the multi-mode laser beam with the straightedge. This advancement continues until the error signal is a null and the zero—zero mode pulsed laser beam is thereby isolated.

Abstract: The all-optical pulse generating and amplifying system utilizes a phosphor that is excited by input light of a first wavelength and, in response, emits light of a second wavelength. The light emitted by the phosphor illuminates a bistable element which, at a pre-fixed intensity of the phosphor-emitted light, switches from non-transmissive state to transmissive state, thereby allowing the exit of light (also of first wavelength) emitted by an output light source as light pulse output of the system. An inhibitory light that also passes through the bistable element during its transmissive state quenches the phosphor light emission and returns the bistable element to its non-transmissive state and re-starts the process toward the next transmissive state. By gating the intensity, via selected non-linearity of the bistable element, of the light output in proportion to the intensity of the input light, the system can also function as an amplifier.

Abstract: The larger the number of successive “0”s preceding a “1” in input data applied to a semiconductor laser, the longer the emission delay time of the laser. Accordingly, if a pulse signal for driving the semiconductor laser is made to rise earlier by an amount equivalent to the emission delay time conforming to the number of successive “0”s, thereby enlarging the pulse width, then the emission delay can be compensated for to eliminate pattern jitter irrespective of the number of successive “0”s. To accomplish this, a unit is provided for monitoring the number of successive “0”s in the input data, and a pulse-width adjustment circuit is provided for advancing the rise time of the laser driving pulse, thereby enlarging the pulse width, based upon the number of successive “0”s preceding a “1” in the input data.

Abstract: At least one monitor laser having an associated monitor diode. The monitor diode is connected to an electronic circuit that controls the monitor laser, while correspondingly driving the semiconductor lasers in parallel, in such a way that an electrical signal from the monitor diode constantly has a preset value. This value and a nominal signal corresponding to the nominal value of the optical power of the monitor laser are used to form a correction variable. If a current flowing through a semiconductor laser exceeds the current through the monitor laser, weighted by the correction variable, then the power of the semiconductor laser is reduced. In this manner, the transmitting device is of simple construction and at the same time avoids unacceptably high powers in the semiconductor lasers.

Abstract: A highly stable soliton source uses a bulk Er/Yb glass laser which operates in two longitudinal modes of the laser cavity with substantially identical amplitudes to generate beat modulation. The beat modulation is then passed through a pulse compression fiber which compresses the beat modulation into a train of soliton pulses. Because the beat modulation is between two modes of the same laser cavity, the soliton pulse train generated is highly stable with low timing jitter.

Abstract: This invention relates to a new diode pumped solid state laser which has a miniature Q-switching device in the cavity. Nd:YAG, Nd:YLF or Nd:YVO4 are useful solid state laser materials for Q-switching. A compact thermo-electric (TE)cooled diode laser unit is used as a pump source, and high-speed switching of the drive current driver is provided for the precise pump energy control. By using the variable high-speed switching pump source, the energy of each Q-switched output pulse from the laser can be controlled precisely and the usual “giant pulse” from the Q-switch can be eliminated. Also, the pulse energy can be controlled precisely independent of the repetition rate or switching speed of the Q-switch without using other feedback components. The Q-switch is synchronized to open at the end of each diode pump pulse.

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: A pulsed laser is provided wherein the B-integral accumulated in the laser pulse is reduced using a semiconductor wafer. A laser pulse is generated by a laser pulse source. The laser pulse passes through a semiconductor wafer that has a negative nonlinear index of refraction. Thus, the laser pulse accumulates a negative B-integral. The laser pulse is then fed into a laser amplification medium, which has a positive nonlinear index of refraction. The laser pulse may make a plurality of passes through the laser amplification medium and accumulate a positive B-integral during a positive non-linear phase change. The semiconductor and laser pulse wavelength are chosen such that the negative B-integral accumulated in the semiconductor wafer substantially cancels the positive B-integral accumulated in the laser amplification medium. There may be additional accumulation of positive B-integral if the laser pulse passes through additional optical mediums such as a lens or glass plates.

Abstract: An optical functional amplifying device suitable for use in an optical gate which operates at a very high repetition frequency such as a frequency exceeding 100 GHz. The device has a semiconductor laser amplifier having a gain section and a saturable absorber section, a first optical coupler for coupling an input signal optical pulse train having a wavelength whose value is set near the absorption edge of the saturable absorber section in the semiconductor laser amplifier, a second optical coupler for coupling a gate optical pulse train having a wavelength shorter than that of the input signal optical pulse train to the semiconductor laser amplifier, and a selector for separating and extracting a signal optical pulse train emitted from the semiconductor laser amplifier from the gate optical pulse train.

Abstract: A pulsed solid state laser system is disclosed which utilizes a plurality of individual laser rods which are sequentially pumped and whose beans are combined into a single interleaved output bean. The individual laser rods are pumped at an average power level which is below that for maximum output power from each rod, thereby obviating the need for refrigeration cooling. A compact optical system is disclosed which permits a constant beam size even at different pump levels and other advantages. A compact cooling system is also disclosed.

Abstract: The object of the present invention is to provide an optical pulse generator which very stably generates for a long period of time a high cycling frequency optical pulse chain. In order to obtain this object, in a ring type resonator R, the present invention provides an optical path length regulator 14 which performs high precision optical path length adjustment and an optical path length regulator 60 which performs wide range optical path length adjustment, and extracts a clock signal by converting an optical pulse emitted from the ring type resonator R to an electrical signal by a clock extractor 42, detects the frequency difference between a base frequency signal output form a synthesizer 52 by a frequency difference detector 50, and controls said optical path length regulator 14 and said optical path length regulator 60.

Abstract: The laser beam produced by the improved precision laser maintains an axial stability of less than 20 micro-radians in the presence of ambient temperature changes and shock and vibration of as much as 100 g's, achieving a new milestone in stability. In the new laser one end of the resonator (7) is hard mounted to the laser bench (13) and the other end of the resonator is mounted to that laser bench by a flexure (17). The flexure is designed to resiliently yield in the presence of thermally induced strain on the bench while retaining sufficient stiffness against foreseeable shock and vibration.

Abstract: A wavelength shift correction system for a laser system is provided for correcting wavelength chirps. This wavelength shift correction system includes a learning algorithm that learns characteristics of a wavelength chirp from a laser and a computer system that executes the learning algorithm and provides wavelength correction control signals based on the learned characteristics to reduce the magnitude of the wavelength shift of the present wavelength chirp and subsequent wavelength chirps.

Abstract: Disclosed is a two-level current driver suitable for driving a semiconductor laser for printing applications, the laser driver including a primary power source for producing a first current pulse of amplitude I.sub.1 and of duration T.sub.2, a secondary power source for producing a second current pulse of amplitude I.sub.2 and of duration T.sub.1, means for combining the outputs of the power sources, and sensing means for detecting the current pulse output from the primary power source.

Abstract: A pulsed-laser includes a pump-light source, a gain-medium and a Q-switch. The Q-switch has an on-mode in which it is substantially transparent, and an off-mode in which it is normally substantially opaque. A gate-signal switches the laser between a ready-mode in which no pulses are delivered and a pulse-drive mode in which pulses are delivered. A first-pulse controller is provided for controlling the energy in the first of a series of pulses to be delivered by the laser. The first-pulse controller controls the first pulse energy by operating one or more of the Q-switch and the pump-light source in such a way that after switching from the ready-mode to the pulse drive mode the energy in the gain-medium at the instant of triggering the first pulse in the series of pulses is about the same that which will be reached in the gain-medium prior to triggering of subsequent pulses in the series. In this way, all pulses in the series have the about the same energy.

Abstract: Even in the case of variations in the pulse repetition frequency, a solid-state laser generates laser pulses with constant beam characteristics in such a way that when the pulse repetition frequency of the laser pulses is varied the pulse duty factor of the pumping radiation is kept constant and Q switching is triggered in each case at a prescribed period after the start of the pumping pulse.

Abstract: There is provided a mode-locked semiconductor laser including a saturable absorber section, a gain section having the same composition as that of the saturable absorber section, a non-absorptive waveguide section having an absorption edge wavelength shorter than an oscillation wavelength of the gain section, an electroabsorption modulator section having an absorption edge wavelength intermediate between an oscillation wavelength of the gain section and an absorption edge wavelength of the non-absorptive waveguide section, and a distributed Bragg reflector section having the same composition as that of the non-absorptive waveguide section and including a diffraction grating. These five sections are optically coupled to one another in a single waveguide.

Abstract: A high pulse rate pulse power source for supplying controlled high energy electrical pulses at rates of 2000 Hz or greater. The source includes a pulse generating circuit including a charging capacitor, a solid state switch and a current limiting inductor. Pulses generated in the pulse generating circuit are compressed in at least two pulse compression circuits and a step-up pulse transformer increases peak voltage to at least 12,000 volts. A very fast regulated resonant power supply is provided for charging the charging capacitor in less than 400 microseconds and a pulse control system including a programmed processor controls the charging of the charging capacitor to an accuracy of less than about one percent at a rate of at least 2000 charges per second.

Abstract: The invention relates to a method and apparatus for shaping a laser pulse. The method comprises the steps of generating a laser pulse with a laser, opening an optical switch to allow the laser pulse to pass through the optical switch, determining a first reference time point with respect to the laser pulse, determining a second reference time point with respect to the opening of the optical switch, and adjusting an opening time of the optical switch based on the first and second reference time points to shape the laser pulse.

Abstract: A system and method for reducing pulse-to-pulse energy and peak power variation in various types of pulsed lasers, and in Q-switched lasers in particular. The system of invention has a laser cavity with a lasing medium pumped by a pumping device for delivering to the medium a pumping energy E.sub.pump. The system further includes a detection device and circuitry for determining the pulse magnitudes M.sub.i of laser pulses i, such as peak pulse amplitudes A.sub.i, pulse energies E.sub.i, pulse widths W.sub.i or other pulse metrics. According to the method of invention, a feedback mechanism which is in communication with the pumping device ensures pulse-to-pulse stability by increasing the pumping energy E.sub.pump when pulse magnitude M.sub.i of laser pulse i exceeds a mean pulse magnitude [M] and decreasing the pumping energy E.sub.pump when M.sub.i is less than [M]. Alternatively, the feedback mechanism is in communication with the switching device which controls that variable loss factor of the Q-switch.

Abstract: An exposure apparatus comprising (a) irradiating means for illuminating a mask with laser light from an excimer laser and (b) a projection optical system for projecting a pattern of the mask onto a substrate with the laser light, wherein a characteristic of the projection optical system is measured by use of a harmonic of a predetermined laser, and wherein the laser light from the excimer laser has a wavelength corresponding to that of the harmonic of the predetermined laser.

Abstract: A laser diode driving apparatus produces a simple write signal having an attenuated waveform to drive the laser diode. A laser diode emits laser light on an optical disk according to a write signal to record data thereon. A laser diode driver outputs a predetermined, plurality of write power values each being different from each other. A write control signal generator calculates widths of a kick pulse and a brake pulse corresponding to the pulse width of the received NRZI signal, and generates write control signals in a predetermined order for controlling write power values corresponding to the calculated widths of the kick pulse and the brake pulse. A write signal generator supplies a write signal to the laser diode using a plurality of the write power values according to the write control signals generated by the write control signal generator. Accordingly, a write domain can be made to be close to a distinct oval.

Abstract: In order to provide an optical transmitter applicable for a transmission speed range higher than 1 Gb/s without transmission quality degradation, the embodiment of the invention comprises a flipflop having a set terminal supplied with a transmission signal and a variable delay circuit for delaying an inverse output of the flipflop to be supplied to a reset terminal of the flipflop, for equalizing pulse width of the laser light with that of the transmission signal.

Abstract: An energy quantity control method usable with a pulse energy producing source for successively emitting energy pulses of an energy quantity variable with time, wherein a control parameter for the pulse energy producing source is adjustable to control an energy quantity of an energy pulse, the method including determining, on the basis of a difference between a desired value for integrated energy quantity of energy pulses and an actually measured value for the integrated energy quantity, a desired value for a subsequent energy quantity to be provided subsequently by a subsequent energy pulse, and adjusting the control parameter on the basis of a difference between the desired value for the subsequent energy quantity to be provided subsequently by the subsequent energy pulse and an actually measured energy quantity provided by a last-emitted energy pulse.

Abstract: A pulse laser system for providing precise control of laser pulse energy. A fast pulse energy detector having response time in the nanosecond or sub-nanosecond range provides an electrical signal representing pulse energy to a trigger circuit, which integrates the signal and triggers an electro-optic switch when the integrated signal reaches a predetermined level. The operation of the electro-optic switch trims a portion of the pulse energy so that the resulting pulse energy is maintained at a consistent and desired level. In a preferred embodiment, the electro-optic switch includes a Pockels cell and at least one polarizing beam splitter. In this preferred embodiment, an optical delay line provides additional time for the pulse trimming components to operate.

Abstract: The energy of a series of output pulses of a solid state laser pumped by a diode array and triggered by a Q-switch is stabilized and rendered independent of the repetition rate by interrupting the pumping to allow the energy stored in the laser active element to fall at the commencement of an interval between a pair of Q-switch trigger signals that is longer than the interval corresponding to the chosen repetition rate. Before the second of this pair of Q-switch trigger signals occurs, the pumping is recommenced for a duration and at an input level that restore the stored energy to the value required for generating output pulses of the laser at the desired energy level.

Abstract: A high average power, high brightness solid state laser system. We first produce a seed laser beam with a short pulse duration. A laser amplifier amplifies the seed beam to produce an amplified pulse laser beam which is tightly focused to produce pulses with brightness levels in excess of 10.sup.11 Watts/cm.sup.2. Preferred embodiments produce an amplified pulse laser beam having an average power in the range of 1 kW, an average pulse frequency of 12,000 pulses per second with pulses having brightness levels in excess of 10.sup.14 Watts/cm.sup.2 at a 20 .mu.m diameter spot which may be steered rapidly to simulate a larger spot size. Alternately, a kHz system with several (for example, seven) beams (from amplifiers arranged in parallel) can each be focused to 20 .mu.m and clustered to create effective spot sizes of 100 to 200 .mu.m. These beams are useful in producing X-ray sources for lithography.

Abstract: A pulse generator is provided with a photoconductor in which first to third transmission lines composed of conductive film are formed on a semi-insulating substrate and the transmission lines are separated by first and second narrow gaps, and provides short pulses from short electrical pulses generated on these transmission lines in accordance with short optical pulses irradiated upon each narrow gap. Semiconductor lasers effect the irradiation of short optical pulses upon the first and second narrow gaps. A delay is conferred upon short optical pulses irradiated upon one of the first and second narrow gaps such that pulse height of short electrical pulses generated on the first to third transmission lines is maximized.

Abstract: An optical clock regenerator using a laser includes an optical modulator for mode locking in a laser resonator. The optical modulator is driven by an intensity-modulated optical signal. When an intensity-modulated optical data pulse train including a clock frequency component close to a frequency n (n is an integer) times or one-nth times a resonance frequency of the laser resonator is input to the optical modulator, the laser outputs clock pulse light locked by the frequency n times or one-nth times a clock frequency of the optical data pulse train. The optical data pulse train and the laser resonator are spatially separated from each other.

Abstract: The generation of ultrashort pulses with adjustable repetition rates from passively modelocked fiber lasers is demonstrated. By inserting semiconductor saturable absorbers with life-times of the order of 10 nsec into fiber lasers with cavity round-trip times of the order of 100 nsec, passive harmonic modelocking is obtained, leading to the stable generation of pulses at integer multiples of the fundamental cavity frequency. For polarization states that allow for optical limiting of the lasers, pulses are obtained in a frequency range between 20 and 500 MHz., where different repetition rates can be simply selected by changing the pump power level to the cavity. The pulse jitter within one cavity round-trip time is measured to be between 300 psec and 50 psec, where side bands in the frequency domain may be suppressed by up to 70 dB.

Abstract: A light pulse generator is disclosed comprising an optical main-loop, a pumped-light source, a delay optical fiber, and an optical switch controller. The optical main-loop circulates a light and includes a light mixer, a light isolator, an erbium-doped optical fiber, an optical switch, a light divider, and an optical fiber coupler. The pumped-light source generates a pumped-light and introduces the pumped-light into the optical main-loop through the light mixer. The terminals of the delay optical fiber are connected to the optical fiber coupler so as to form an optical sub-loop for spreading a pulse width of a light pulse circulating in the optical main-loop. The optical switch controller switches the optical switch to an ON-state. As a result, a positive feedback amplification is carried out in the optical main-loop and an output light pulse having a sufficiently long pulse width and sufficiently high power is picked up from the optical loop through the light divider.

Abstract: An optical communication system is disclosed including an all-optical device whose output modulated optical beam is locked to an input modulated optical beam. In a specific embodiment of the system, the device may be a self-electro-optic effect device (SEED), which is operated as an oscillator by means of an associated tank circuit. Such an embodiment permits recovery of a clock frequency from a bit stream which is input into the device. When the output of the device is directed into an optical decision element, an all-optical regenerator may be realized.

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

Abstract: Chromatic and polarization dispersion and transmitter frequency chirp are the dominant data rate limiting factors for high-speed, long distance communication systems. To overcome such limitations, a chromatic and polarization dispersion and frequency chirp compensator is utilized. The applicants provide a compensator by combining a wavelength to polarization transformer with a polarization to delay converter having a dispersion characteristic of substantially equivalent in magnitude, and opposite in sign, to the desired amount of dispersion and frequency chirp to be compensated. Optical gain may be incorporated in any of the elements of the compensator which makes the present invention a lightwave amplifier as well as a dispersion compensator. The present invention is also applicable as an optical pulse time compressor that compresses a relatively long width optical pulse to a short width pulse.

Abstract: An electro-optical device includes a vertical cavity surface emitting laser, a heterojunction light emitting device and heterojunction phototransistor on a semiconductor substrate. Layers of the heterojunction phototransistor and the heterojunction light-emitting device are electrically and optically coupled so there is regenerative optical and electrical feedback between them. Layers of the heterojunction light-emitting devices are proton implanted to control the feedback. Plural such devices are electrically and optically coupled together to perform logic functions, such as EXCLUSIVE OR, in response to optical signals.

Abstract: The invention provides a method and apparatus for generating high pulse energy, short optical pulses having relatively high contrast. The system comprises a diode laser to seed a compact diode pumped amplifier, and comprises pulse shaping and cleaning elements to achieve relatively high energies and high contrast. The system is not locked to a fixed repetition rate as it is controlled by an electronic trigger. The system of the invention comprises a selectively triggered pulse source (asynchronous) which is coupled to pulse amplifying/pulse shaping means, which is coupled to pulse cleaning means, which is further coupled to a chirped pulse amplification (CPA) system.

Abstract: A fiber laser for producing high energy ultrashort laser pulses, having a positive-dispersion fiber segment and a negative-dispersion fiber segment joined in series with the positive-dispersion fiber segment to form a laser cavity. With this configuration, soliton effects of laser pulse circulation in the cavity are suppressed and widths of laser pulses circulating in the cavity undergo large variations between a maximum laser pulse width and a minimum laser pulse width during one round trip through the cavity. The fiber laser also provides means for modelocking laser radiation in the laser cavity, means for providing laser radiation gain in the laser cavity, and means for extracting laser pulses from the laser cavity.

Abstract: An optical transmitter for use, for example in a TPON (telecommunications over passive optical networks) network, has a servo circuit for controlling the optical output power of an optical source of the transmitter. In a power setting operation used for bringing the output power to a demand level when the transmitter is first connected to the network, the servo circuit causes the source to produce a series of optical pulses and monitors the power of the pulses using an optical sensor coupled optically to the source. If the modified power level of a pulse is less than the demand level then in the next pulse the drive signal value (I.sub.D) applied to the source is increased, relative to the drive signal value for the present pulse, by a predetermined adjustment amount, whereas if the monitored power level is greater than the demand level the drive signal value is decreased by the predetermined adjustment amount.