Abstract: A gas discharge laser system bandwidth control mechanism and method of operation for controlling bandwidth in a laser output light pulse generated in the gas discharge laser system is disclosed which may comprise a bandwidth controller which may comprise an active bandwidth adjustment mechanism; a controller actively controlling the active bandwidth adjustment mechanism utilizing an algorithm implementing bandwidth thermal transient correction based upon a model of the impact of laser system operation on the wavefront of the laser light pulse being generated and line narrowed in the laser system as it is incident on the bandwidth adjustment mechanism. The controller algorithm may comprises a function of the power deposition history in at least a portion of an optical train of the gas discharge laser system, e.g., a linear function, e.g., a combination of a plurality of decay functions each comprising a respective decay time constant and a respective coefficient.

Abstract: Methods and systems that enable the combining of laser diodes into a laser beam.

Abstract: Disclosed is a semiconductor laser in which the substrate comprises at least three independent functional sections in the direction of light wave propagation, said functional sections serving different functions and being individually triggered by means of electrodes via electrode leads. An intensification zone, a grid zone, and a phase adjustment zone are provided as functional sections. The light wave is optically intensified in the intensification zone while the phase of the advancing and returning wave is adjusted in the phase adjustment zone. The grid zone is used for selecting the wavelength and adjusting the intensity of coupling between the intensification zone and the phase adjustment zone.

Abstract: A high power laser system is provided having a master oscillator for generating a reference laser beam of desired beam quality, means for dividing the reference beam into multiple sub-beams, a multi-slab gain module positioned to receive the multiple sub-beams as input beams, and means for adjusting the sub-beams in phase to allow the output sub-beams to be coherently combined as a single composite output beam. Optionally, additional multi-slab gain modules similar to the first multi-slab gain module may be positioned to receive amplified output sub-beams from the first multi-slab gain module. The additional multi-slab gain modules generate further amplified output sub-beams of high aggregate power.

Abstract: A semiconductor optical amplifier, an acousto-optic tunable filter, a phase shifter, a lens, and an internal etalon are arranged in a resonator. Outside the resonator, two lenses, two beam splitters, two photo-detectors, and an external etalon are arranged. The internal etalon is a quartz etalon and the external etalon is a crystal etalon. Therefore, the rate of change in transmission peak wavelength of the internal etalon to a temperature change is greater than that of the external etalon.

Abstract: Both a system and method are provided for modulating the intensity of an output beam generated by semiconductor laser. The exemplary system includes a source of pulsating current connected to the laser that generates a pulsating beam of laser light, an external modulator having an input that receives the pulsating beam, and an output controlled by pulsating control signal, wherein the output beam transmitted by the external modulator output is modulated by changing a relative phase angle between the pulsating current powering the laser, and the control signal of the external modulator over time. The external modulator may be an intensity-type modulator whose output is controlled by a gate signal having a constant phase, and the source of pulsating current powering the laser may be variable phase in order to modulate the output beam with an external modulator having a simple structure.

Abstract: A laser apparatus for providing a stabilized multi mode laser beam includes an external cavity for providing an optical path for generating a laser beam which is stimulated by a gain medium, where the external cavity has first spectral characteristics, and a mode-selecting filter positioned within the optical path and having second spectral characteristics. The first characteristics and the second characteristics are adjusted to each other, so that the laser beam has at least two selected modes.

Abstract: The so-called single-longitudinal mode of operation of a tunable laser beam source requires active control of the band-pass filters mounted in the laser resonator. As a rule, this entails one, or a combination of several filter elements, as for example birefringent filters, as well as etalons. In either case, the band-pass filter needs to be so adjusted as to locate precisely one of the feasible longitudinal modes of the laser at the exact maximum transmission of the band-pass filter. The invention consists in regulating such filter setting by way of a program-controlled digital signal processor DSP in such a way that the DSP modulates the filter element with an adjustable frequency, and such regulation exploits the phase of the laser intensity fluctuations induced thereby to regulate the optimal position of the band-pass filter.

Abstract: A system and method for combining plural low power light beams into a coherent high power light beam by means of a diffractive optical element operating as both a beam combiner and beam sampler. An oscillation source transmits a master signal that is split into plural beams propagating at a common wavelength. Each beam is phase locked by a corresponding phase modulator according to a phase correction signal. The beams are directed through a fiber array to the diffractive optical element to allow efficient coherent combination of the beams at a desired diffraction order. The diffractive optical element includes a periodic sampling grating for diffracting a low power sample beam representative of the combined beam. A phase detection stage detects phases of constituent beams in the sample beam from which the phase correction signals are derived and fed back to the phase modulators.

Abstract: Provided are a small-sized, low-cost, and easy-to-use laser optical path length difference detecting device, a laser optical path length difference detecting device, and a coherent optical coupling device. The laser optical path length difference detecting device detects an optical path length difference between propagation paths of a first laser beam (1) and a second laser beam (2), which are mutually coherent when the beams are propagated through two arbitrary optical paths of a plurality of laser beam optical paths.

Abstract: An optical beam combiner and a related method for its operation, in which multiple coherent input beams are directed onto a diffractive optical element (DOE) along directions corresponding to diffraction orders of the DOE, such that the DOE generates a single output beam in a direction corresponding to a desired diffraction order, and suppresses outputs in directions corresponding to unwanted diffraction orders. The phases of the input beams are actively controlled to ensure and maintain the condition that only a single diffraction mode is present in the output of the DOE.

Abstract: The present invention is directed to a method and system for providing phase modulated current to a semiconductor laser to control beam wavelength. A first current is received into a gain portion of the semiconductor laser and a second current is received into a DBR portion of the semiconductor laser. The second current is phase modulated based upon a required intensity value. An output beam is generated by the semiconductor laser based upon the received first current and the received second current.

Abstract: An array of optically coupled cavities (called micro-cavities) of a semiconductor laser are defined by either an etch and/or by a native oxide of an aluminum-bearing III-V semiconductor material and are arranged serially end-to-end along the longitudinal direction. An etch and/or native oxide defines a refractive index change for the longitudinal optical mode and confines the optical field within the micro-cavities, resulting in reflection and optical feedback distributed periodically along the laser stripe in the form of an optically coupled micro-cavity. The wavelength of emission of the laser is controlled by a combination of the length of the optical micro-cavities and the spacing between adjacent optical micro-cavities. Single-longitudinal-mode operation is exhibited over an extended drive current range. In one embodiment, two or more linear arrays of end-coupled micro-cavities are arranged in the longitudinal axis of the laser cavity to obtain a tunable laser.

Abstract: A system or method coherently combines a large number of light beams at a single wavelength in multiple stages to form a high-power diffraction limited output beam. A two-stage system, or method based thereon, includes a master oscillator transmitting a light beam to a first phase modulation stage, which splits the beam into N beams and locks beam phases using phase correction signals from a first feedback loop. A second phase modulation stage splits each N beam into M beams and locks the phases of M beams in each N group using phase correction signals from a second feedback loop. A two-dimensional fiber array directs M×N beams to a first diffractive optical element combining the beams into N coherent beams of M beams each, and phase correction signals for the second stage are derived from a sample extracted from the N coherent beams.

Abstract: Provided are a small-sized, low-cost, and easy-to-use laser optical path length difference detecting device, a laser optical path length difference detecting device, and a coherent optical coupling device. The laser optical path length difference detecting device detects an optical path length difference between propagation paths of a first laser beam (1) and a second laser beam (2), which are mutually coherent when the beams are propagated through two arbitrary optical paths of a plurality of laser beam optical paths.

Abstract: A single-mode grating-outcoupled surface emitting (GSE) semiconductor laser architecture is provided. This architecture enables high speed modulation of the GSE laser, which is accomplished by only varying the relative phase of counter propagating waves in the outcoupler grating region of the lasing cavity.

Abstract: Wavelength control and stabilization of a laser is achieved by a practical, inexpensive, and accurate technique adapted for most optical transmission system applications by a method involving a laser characterization phase and a laser wavelength control and stabilization phase. This technique is applicable to both single mode lasers and multimode lasers. It is especially useful in those applications where the desired laser output power can vary over a wide range, including relatively low power above the lasing threshold.

Abstract: An optical transmission controller includes a semiconductor-laser, a semiconductor laser driver, a monitor photoreceptor, a waveform detector and a phase relation adjuster. The semiconductor laser driver allows the semiconductor laser to output an optical signal. The monitor photoreceptor monitors the optical signal output. The waveform detector detects a fall state of the optical signal output. The phase relation adjuster adjusts a phase relation between a fall timing of an input current and a variation timing of a relaxation oscillation of the optical signal output in accordance with a detection result of the waveform detector.

Abstract: A system for tuning the wavelength of a beam from a tunable laser. A tunable etalon assembly includes a Fabry-Perot etalon with paired reflectors to filter the laser beam. The tunable etalon also includes a thermal unit to thermally adjust the separation of the paired responsive to an etalon tuning signal. A photodetector receives the laser beam after filtering the etalon and generates a detected signal based on intensity. A controller generates the etalon tuning signal, and receives the detected signal and generates a laser tuning signal based on it. Optionally, additional Fabry-Perot etalons, photodetectors, and one or more beamsplitters permit extending wavelength range and determining relative wavelength difference with a beam from a second laser.

Abstract: There is provided a phase control portion for controlling phase of a laser beam resonated in a resonator based on detected results by two optical detectors. The phase control portion adjusts the longitudinal mode positions by a feedback control so that a ratio of intensities detected by the two optical detectors comes to a predetermined reference value. To one of the optical detectors, part of a laser beam outputted from the resonator is irradiated as it is, whereas, to the other one of the optical detectors, part of the laser beam outputted from the resonator is irradiated after passing through an etalon. An FSR of the etalon is a double of that of another etalon in the resonator.

Abstract: This invention relates to opto-electronic systems using semiconductor lasers driven by feedback control circuits that control the laser's optical phase and frequency. Feedback control provides a means for coherent phased laser array operation and reduced phase noise. Systems and methods to coherently combine a multiplicity of lasers driven to provide high power coherent outputs with tailored spectral and wavefront characteristics are disclosed. Systems of improving the phase noise characteristics of one or more semiconductor lasers are further disclosed.

Abstract: An injection locking type or MOPA type of laser device capable of always providing stable output energy and wavelength is provided. For this purpose, the laser device includes an oscillator for exciting laser gas by oscillator discharge and oscillating seed laser light with band-narrowed wavelength, an amplifier for amplifying the seed laser light by amplification discharge to emit amplified laser light, a delay circuit for setting at least one of a delay time from light emission of the seed laser light to light emission of the amplified laser light, and a delay time from start of the oscillator discharge to start of the aforementioned amplification discharge, and a delay time compensation circuit for performing compensation of the delay circuit so that the delay time becomes an optimal delay time.

Abstract: A solid state zig-zag slab laser amplifier in which depolarization occurring at total internal reflection from opposed lateral faces of the amplifier slab is controlled by selecting a complex evanescent coating that provides a selected phase retardance that results in minimization of depolarization. Without use of the complex coating, small changes in incidence angles can result in phase retardance changes large enough to increase depolarization significantly, especially when the amplifier is operated at higher powers. Appropriate selection of the complex evanescent coating allows a desired phase retardance angle to be maintained relatively constant over a small range of angles of incidence, at a given wavelength, and therefore permits minimization of depolarization and birefringence effects.

Abstract: The object is to provide a highly reliable, high-performance, and low-price tunable light source and the like. The present invention comprises: a multiple resonator that oscillates with a wavelength where frequencies of three or more resonant elements with shifted cycles intersect; and a tunable device for controlling the resonant wavelength of the multiple resonator by simultaneously changing the respective optical path lengths of the plurality of resonant elements constituting the multiple resonator.

Abstract: This invention describes a technique and apparatus to use any tuneable laser to generate a specified output frequency without controlling its temperature. This technique only involves a thermal sensor and a controller to determine the current(s) or voltage(s) applied to the grating or tuning section(s) to obtain the required wavelength. The control loop can be implemented using a programmed microprocessor, an amplifier and a low pass filter.

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 driving method of a semiconductor laser having an active layer region, a phase adjustment region and a distributed Bragg reflector region includes the steps of: calculating an average value of multipulse modulation currents modulated between a peak current and a bottom current input to said active layer region; calculating a difference between the average value of the multipulse modulation currents and a bias current input to the active layer region; and applying a first compensation current to the phase adjustment region when the multipulse modulation current is input to the active layer region, and applying a second compensation current corresponding to the difference to the phase adjustment region when the bias current is input to the active layer region.

Abstract: Systems, methods and computer software are provided for testing a laser. Initially, the laser is operated at a first bias setting and a data rate of about 10 Gb/s, and a first side mode suppression ratio of the laser output is measured that is based on a first ratio of a highest and next highest optical power peaks as a function of a first wavelength. Next, the laser is operated at a second bias setting and a data rate of about 10 Gb/s, and a second side mode suppression ratio of the laser output is measured that is based on a second ratio of a highest and next highest optical power peaks as a function of a second wavelength. A test result for the laser is then generated in accordance with a difference between the first and second side mode suppression ratios.

Abstract: A coherent laser beam combining system wherein the output of a single master oscillator is split into a plurality of N signals, and the N signals are electronically modulated at unique frequencies. There is no reference signal and all of the signals are passed through phase adjusters. All N signals are optically amplified, aligned and passed through a beam splitter to split off a small sample that is imaged onto a photodetector. The photodetector output is fed to a signal processor that separates the N signals and produces N phase error signals that drive the N phase adjusters resulting in a high-powered optically coherent output signal.

Abstract: A device for coupling incident radiation to a single mode fiber optic a solid state interferormeter having a front end similar to a Mach-Zehnder integrated interferometer and a back end formed by two converging radiation channels converging at an angle ? and terminating prior to overlapping. The angle ? is calculated to produce an interference zone formed by the exiting radiation a primary constructive interference fringe that provides an optimum match to an input fiber mode of a fiber positioned within the interference zone.

Abstract: A controller for use with sampled grating distributed Bragg reflector (SGDBR) lasers is presented. An exemplary controller includes a table of settings representing a control surface, each setting corresponding to a separate operating point of the SGDBR laser, a first mirror current controller and a second mirror current controller. The first mirror controller and the second mirror current controller respectively control a first mirror current and a second mirror current about an estimated extremum point of the control surface to substantially maintain alignment between each of a first mirror and a second mirror, and an associated cavity mode. The first mirror current and the second mirror current can be locked at a substantially fixed distance from the extremum of the control surface.

Abstract: One embodiment of the present invention includes an optical cavity, a source to provide light to the optical cavity, a sensor to detect the light and generate a corresponding sensor signal, and a servo device including a feedforward input and a feedback input. Feedback from the sensor signal is provided to the servo device to regulate operation of the source at a frequency selected to generate an optical field resonating in the first mode in the cavity. An input device provides a control signal to a control input of the servo device that selectively alters operation of the light source to corresponding halt resonance in the first mode. An evaluation device is also included to evaluate decay of the optical field after resonance in the first mode is halted.

Abstract: A light frequency locker (10) able to accept a light beam (14) generated by a controllable light source (12) into a light diverter (16) and impart to it a transverse displacement characteristic which can be detected in a light detection unit (20) connected to a processor (22). The processor (22) then controls the light source (12). Optionally, a light diverger (18) may be provided to enhance angular resolution. The light diverter (16) and the light diverger (18) may either transmit or reflect the light. The light diverter (16) may particularly include a diffraction grating (116, 156), Fabry-Perot interferometer (216), multiple slit plate (316), or an acousto-optical unit (416).

Abstract: The invention concerns an ultrahigh frequency emitting device, having: at least a first and a second microlaser (22, 24), emitting at two different frequencies &ohgr;1 and &ohgr;2, means of slaving the first and the second microlaser frequency-wise, an array of N elements (N≧2) (52, 54, 56, 58) placed on the path of the beam of the second laser, each element making it possible to impose a phase delay on the beam which passes through it, N means (26, 28, 30, 32) for mixing the beam emitted by the first laser and each of the N delayed beams, and for producing N signals of frequency &ohgr;1-&ohgr;2, N antenna-forming means (34, 36, 38, 40) for emitting radiation at the frequency &ohgr;1-&ohgr;2.

Abstract: The invention relates to an improved method and system for synchronizing signals in a particle accelerator system. In one embodiment, a method and system is disclosed whereby a phase of laser pulses are monitored, and a high-frequency signal is adjusted as necessary to be substantially in-phase with the laser pulses. In another embodiment, a method and system is disclosed whereby a phase of an electromagnetic field in an electron gun is monitored, and a high-frequency signal is adjusted as necessary to be substantially in-phase with the electromagnetic field.

Abstract: The invention relates to a method and a circuit arrangement for a laser control loop with automatic adaptation to the monitoring signal polarity. Use is made of a single-phase method which consists in that a signal produced by the monitor during the starting phase of the laser control loop is compared with a reference value, and in accordance with the result of the comparison the signal produced by the monitor is fed directly or inverted to the comparator for controlling the light power of the laser during the starting phase of the laser control loop. A signal is produced which initially feeds the comparator for controlling the light power the inverted monitoring signal, or directly feeds the monitoring signal, in a fashion always independent of the monitoring signal polarity, but dependent on the polarity of a reference value, and feeds it in a non-inverted fashion in the case of a monitoring signal running up to the reference value.

Abstract: An optical system for producing high power laser beams has an in/out coupler for receiving an input laser beam from an oscillator. The coupler inputs the beam to a first multiplexer which produces a plurality of beams which are sent to a plurality of fiber amplifiers. A second beam multiplexer receives the thus amplified plurality of beams to combine then into a single amplified beam which is input to a loop PCM (phase conjugate mirror). A multi-mode fiber amplifier is included in the loop PCM. The output of the loop PCM is phase conjugated with the amplified beam input to the loop PCM thereby eliminating any phase and polarization distortions and aberrations occurring in the fiber amplifiers. The output of the loop PCM is supplied in reverse direction through the second multiplexer, the fiber amplifiers and the first multiplexer in that order and then through the in/out coupler as a high power output laser beam.

Abstract: A stabilized single-longitudinal-mode laser where stabilization is performed through a pair of Bragg reflector mirrors slightly displaced in wavelength to either side of the longitudinal mode selected for operation. Transmitted signals through each Bragg reflector are detected and used in an electrical servo loop to control the relative positions of the longitudinal mode selected for operation and the peak wavelengths of the two Bragg reflector mirrors.