Abstract: A laser and monitoring system 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. In yet another aspect of the present invention, a multiphoton intrapulse interference phase scan (hereinafter “MIIPS”) method is used to characterize the spectral phase of femtosecond laser pulses and to correct them. A further aspect of the system of the present invention is employed to monitor environmental chemicals and biological agents, including toxins, explosives, and diseases.

Abstract: The present invention relates to an atomic frequency acquisition device comprising a gas cell (400) filled with an atomic gas, a laser light source (100) emitting a laser beam which enters the gas cell (40) and excites a first energy transition of the atomic gas, a local oscillator (700) for generating an oscillator frequency in a frequency range including a frequency of a HFS transition of the atomic gas, and a modulator (600) modulating the laser light source (100) so as to emit laser radiation modulated with the oscillator frequency. An optical reflector (500) is arranged behind the gas cell (400) to reflect the laser beam after passage through the atomic gas so as to re-enter the laser cavity. A photodetector (200) detects beat frequencies caused by self-mixing interference within the laser cavity.

Abstract: An apparatus for laser drilling including a laser beam emitter disposed within a housing having at least one laser beam outlet and at least one purge fluid outlet. At least one actuated nozzle is disposed within the housing for providing a purge fluid through the purge fluid outlet and having functional control for synchronized programmable activation patterns. Laser beam control is provided for directing a laser beam over a target surface.

Abstract: A dual output laser source provided on a substrate outputs light from a first and second output. A portion of the light generated by the laser is supplied to a first modulator via the first output. A second portion of the light generated by the laser is supplied to a second modulator via the second output. The first modulator is provided on the substrate and generates a first modulated signal. The second modulator is also provided on the substrate and generates a second modulated signal. Each output of the laser is used to provide continuous wave light sources to components on photonic integrated circuit.

Abstract: A feedback control module for stabilizing a carrier-envelope phase of an output of a laser oscillator system comprises a first photodetector, a second photodetector, a phase stabilizer, an optical modulator, and a thermal control element. The first photodetector may generate a first feedback signal corresponding to a first portion of a laser beam from an oscillator. The second photodetector may generate a second feedback signal corresponding to a second portion of the laser beam filtered by a low-pass filter. The phase stabilizer may divide the frequency of the first feedback signal by a factor and generate an error signal corresponding to the difference between the frequency-divided first feedback signal and the second feedback signal. The optical modulator may modulate the laser beam within the oscillator corresponding to the error signal. The thermal control unit may change the temperature of the oscillator corresponding to a signal operable to control the optical modulator.

Abstract: A pulse width modulation signal generating device which generates a pulse width modulation signal for modulating laser beam according to image data includes: a cycle signal output circuit which outputs a cycle signal having a cycle corresponding to a drawing rate for drawing the image data by the laser beam; and a pulse width modulation circuit which receives supply of the image data and the cycle signal and modulates a pulse wave having a cycle determined by the cycle signal by changing duty ratio of the pulse wave based on the image data to produce the pulse width modulation signal.

Abstract: A system generates FIR laser radiation. An electron source generates an electron beam. A grating horn interacts with the electron beam to produce the FIR laser radiation. The grating horn may comprise a flat base and a pair of grating elements attached to the base, each of the grating elements being ruled with a grating period, the grating elements oriented in phase and in substantial symmetry about a normal to the flat base.

Abstract: Narrow surface corrugated gratings for integrated optical components and their method of manufacture. An embodiment includes a grating having a width narrower than a width of the waveguide on which the grating is formed. In accordance with certain embodiments of the present invention, masked photolithography is employed to form narrowed gratings having a desired grating strength. In an embodiment, an optical cavity of a laser is formed with a reflector grating having a width narrower than a width of the waveguide. In another embodiment an integrated optical communication system includes one or more narrow surface corrugated gratings.

Abstract: A laser device of an equal-energy pulse synchronous with motion includes: a resonant cavity, outputting a plurality of pulses with stable pulse-width and energy; a beam switch modulator, selectively enabling one of the pulses to pass; a beam energy modulator, adjusting the energy of the pulse according to a power feedback signal; an optical power sensor, sensing the energy and the pulse-width of the pulse; a motion controller, providing processing motion information; an optical feedback controller, outputting the power feedback signal to the beam energy modulator according to the energy of the pulse and the processing motion information; a trigger controller, measuring a time difference between time when the pulse is triggered and time when the optical power sensor detects the pulse, and correcting a turn-on time point of the beam switch modulator. The processing quality is therefore stabilized, and the device is applicable to various laser industrial processes.

Abstract: A laser system provides harmonic generation in a laser beam pulse. In another aspect of the present invention, a laser operably remits a laser pulse, a gaseous optical medium operably creates third or greater harmonic generation in the pulse, and a controller characterizes and compensates for distortions in the pulse. A further aspect of the present invention employs multiple optical media arranged to cause cascading harmonic generations in a laser pulse.

Abstract: The configurations of an electro-optic Bragg deflector and the methods of using it as a laser Q-switch in a Q-switched laser and in a Q-switched wavelength-conversion laser are provided. As a first embodiment, the electro-optic Bragg deflector comprises an electrode-coated electro-optic material with one of a 1D and a 2D spatially modulated electro-optic coefficient. When a voltage is supplied to the electrodes, the electro-optic material behaves like a Bragg grating due to the electro-optically induced spatial modulation of the refractive index. The second embodiment relates to an actively Q-switched laser, wherein the electro-optic Bragg deflector functions as a laser Q-switch. The third embodiment of the present invention combines the Q-switched laser and a laser-wavelength converter to form a Q-switched wavelength-conversion laser, wherein the EO Bragg deflector can be monolithically integrated with a quasi-phase-matching wavelength converter in a fabrication process.

Abstract: A laser assembly is configured with a frequency conversion laser head operative to shift a fundamental frequency of input light to the desired frequency of an output light. The frequency conversion laser head includes a dump means operative to guide an unconverted output light at the fundamental frequency outside the case of the frequency conversion laser head. The dump means is configured with a guide optics operative to couple the output light at the fundamental frequency to a fiber terminating outside the case of the frequency conversion laser head.

Abstract: A laser device includes an outcoupling mirror, a laser medium, a phase-conjugate mirror based on stimulated Brillouin scattering, and an end mirror all arranged along an optical axis of the laser device. A controllable modulator is positioned between the phase-conjugate mirror and the end mirror. The outcoupling mirror and the end mirror form a start cavity. The outcoupling mirror and the phase-conjugate mirror form a main cavity.

Abstract: The disclosure provides a bandwidth narrowing module for setting a spectral bandwidth of a laser beam of a laser light source. The bandwidth narrowing module includes a beam expanding module for expanding a laser beam transversely with respect to a propagation direction of the laser beam and comprising a reflection grating. A first optical component of the bandwidth narrowing module is configured so that a disturbance with a cylindrical portion about a first axis transversely with respect to an optical axis of the bandwidth narrowing module can be impressed on a wavefront of a laser beam. The first optical component is embodied such that it is pivotable about a pivoting axis parallel to the first axis.

Abstract: Output pulses from an optical system having a seed source and an optical amplifier coupled to the seed source may be controlled by controlling a power of a seed signal from the seed source. The seed signal may be varied between a minimum value and a maximum value in a way that the seed signal exhibits one or more pulse bursts. Each pulse burst may contain one or more pulses. During an inter-pulse period between successive pulses within a pulse burst or between successive pulse bursts, the power of the seed signal may be adjusted to an intermediate value that is greater than the minimum value and less than the maximum value. The intermediate value is chosen to control a gain in the optical amplifier such that a pulse or pulse burst that follows the period exhibits a desired behavior.

Abstract: A pulsed light generator of the invention includes: an excitation light source; a fiber grating into which excitation light from the excitation light source enters; a rare-earth doped optical fiber optically coupled with the fiber grating, in which a rare-earth element is doped into a core, serving as an optical transmitting section; an optical switch including a deflection element for causing a Q-switching operation; a first optical fiber that causes light from the rare-earth doped optical fiber to enter into the optical switch; and a second optical fiber for waveguiding pulsed light output from the optical switch. One surface side of the optical switch, into which light enters, is subjected to anti-reflection treatment with a reflectance with respect to a wavelength of the pulsed light output from the optical switch being 0.1% or less.

Abstract: In an optical pulse generating apparatus including a metal layer having an incident/reflective surface adapted to receive incident light and output its reflective light as an optical pulse signal, a dielectric layer formed on an opposite surface of the metal layer opposing the incident/reflective surface, and a dielectric layer exciting unit for exciting the dielectric layer on a time basis, the incident light exciting surface plasmon resonance light in the metal layer while the dielectric layer is excited on a time basis, so that an extinction coefficient of the dielectric layer is made negative.

Abstract: A laser system can include a laser and a laser output modulator to modulate the output of the laser.

Abstract: A modulation method according to the invention is applied to a modulation device in which a light source is driven by a differential signal while a modulation circuit and the light source are capacitively coupled. In the modulation method of the invention, when an average potential fluctuates at an input terminal of the light source, a potential fluctuation is externally provided using a control circuit such that a normal phase side and a reverse phase side become equal to each other in a time constant of the fluctuation in average potential, and transient states of the average potentials at the normal phase side and reverse phase side are equalized and cancel each other as in-phase components of a signal input to the light source, which allows an optical signal to be normally transmitted from the light source.

Abstract: A laser system includes a seed laser operable to output a seed laser signal along an optical path and a phase modulator disposed along the optical path and operable to receive the seed laser signal. The laser system also includes a phase modulator driver coupled to the phase modulator. A drive signal from the phase modulator driver is operable to produce, as an output from the phase modulator, an unmodulated seed laser signal when the drive signal is associated with a first state and a modulated seed laser signal when the drive signal is associated with a second state. The laser system further includes a fiber amplifier disposed along the optical path and operable to receive the output of the phase modulator. A spectral bandwidth of an output of the fiber amplifier associated with the second state is less than a spectral bandwidth of the output of the fiber amplifier associated with the first state.

Abstract: The present disclosure relates to a high voltage switch which may comprise a chain of MOS field-effect transistors (MOSFETs). The current of the individual MOSFETS, and hence the chain, can be controlled by means of adding a current measuring resistance into the source path of the transistors and transmitting the voltage arising there via a capacitor to a gate connector of the transistors.

Abstract: Provided is a laser module. The laser module comprises: a substrate; an gain unit oscillating a laser light on the substrate; an external resonance reflecting unit total-reflecting the laser light at an external of the substrate adjacent to one side of the gain unit; and an inner resonance reflecting unit reflecting the laser light to the external resonance reflecting unit at the substrate between the modulating unit and gain unit and outputting the laser light to the modulating unit.

Abstract: A laser processes a workpiece with laser pulses delivered at random time intervals and at substantially constant energy levels by characterizing the laser cavity discharge behavior and utilizing that information for adjusting dummy pulse time periods to compensate for the energy errors. Dummy pulses are laser pulses that are blocked from reaching a workpiece. A second way for providing constant pulse energies employs an AOM for varying amounts of laser energy passed to the workpiece. A third way of providing constant pulse energies entails extending the pulse period of selected pulses to allow additional laser cavity charging time whenever a dummy pulse is initiated.

Abstract: A system for producing a laser pulse includes a laser driver capable of direct modulation of a laser source comprising a plurality of lasers, and a wavelength beam combining cavity, comprising the directly modulated laser source, for producing a wavelength beam combining output of light from the plurality of lasers. The wavelength beam combining cavity may comprise a fast axis wavelength beam combining cavity. The laser source may comprise a multidimensional array of diode lasers disposed in a stack spatially interleaved or optically aligned. Each of the plurality of diode lasers may produce a distinct wavelength.

Abstract: An optical transmitting module of a coaxial type is provided in which a disturbance in a waveform of light which is output from a semiconductor laser element due to a signal which is output from an optical modulator unit can be suppressed. The optical transmitting module comprises an optical transmitting package of a coaxial type and a line board (40) connected to the optical transmitting package. The optical transmitting package comprises a semiconductor laser element, an optical modulator unit, and a conductor board (21). A drive current supply line (42) and a common ground line are formed over the line board (40), and a signal attenuation circuit (60) having one end electrically connected to the common ground line and the other end electrically connected to the drive current supply line (42) is provided over the line board (40).

Abstract: Method for generating a laser pulse for the fine machining of workpieces using a fiber laser, the laser fiber of which is optically pumped by use of at least one diode laser which is operated by a current pulse whose slew rate, pulse height, and pulse length are adjusted in adaptation to the laser fiber in such a way that the laser pulse (22) is initially composed of a primary relaxation pulse (A), independently of the pulse length of the current pulse.

Abstract: The present invention relates to a spectral stretching and control device for high peak power pulse lasers, which does not limit the extraction efficiency of the amplifiers in the CPA chain into which said device can be inserted, and it is characterized in that it comprises an acousto-optical device for dispersing light pulses, which is programmable in terms of spectral amplitude, disposed in a multi-pass amplifier.

Abstract: A method of controlling a frequency-converted laser source is provided where the laser source comprises a laser cavity, an external optical feedback component, a wavelength selective component, and a wavelength conversion device and the method comprises driving a gain section of the laser cavity with a gain signal that comprises a data component and a modulation component. The modulation component of the gain signal comprises a gain modulation amplitude IMOD that is sufficient to shift the available cavity modes in the spectral domain such that lasing at several different cavity modes sequentially is established as the gain signal is modulated.

Abstract: A method of optical communication includes generating an amplified optical signal from at least a portion of a first optical signal having a first carrier wavelength, ?1. The amplified optical signal is applied to Brillouin media to stimulate generation of a Brillouin effect signal at a wavelength ?2. The Brillouin effect signal is modulated to produce a second optical signal having a second carrier wavelength, ?2. In one embodiment, the first optical signal is a downstream optical signal and the second optical signal is an upstream optical signal of a passive optical network.

Abstract: Provided is a method for driving a surface emitting semiconductor laser including an active region that generates light, a resonator structure disposed such that it sandwiches the active region, and a driving electrode that provides power to the active region. The surface emitting semiconductor laser has an internal resistance defined by voltage and current applied to the driving electrode. The method includes applying a modulation signal to the driving electrode, in which the modulation signal has a current amplitude defined by a first current value and a second current value that is greater than the first current value. The modulation signal is in a negative gradient region in which the internal resistance decreases in contrast to the increase of the current.

Abstract: A laser light source device which can inexpensively achieve a visually recognizable level of speckle reduction is disclosed. The laser light source device includes: a laser module including a light source and a first optical waveguide, wherein light emitted from the light source is outputted from an output end of the first optical waveguide; a second optical waveguide connected to the first optical waveguide, wherein the light outputted from the output end of the first optical waveguide is inputted to an input end of the second optical waveguide and guided through the second optical waveguide; and an intensity modulation unit disposed in the vicinity of the second optical waveguide, the intensity modulation unit applying intensity modulation to the second optical waveguide, wherein a core diameter at the input end of the second optical waveguide is larger than a core diameter at the output end of the first optical waveguide.

Abstract: Many approaches to tunable lasers use an array of DFBs, where each element of the array has a different wavelength. In some operations one element of the array is activated at a time depending on the desired wavelength. For modulated applications, an RF voltage is applied to a specific element of the DFB array, generally using an RF switch. In standard configurations, the demands on the switch are relatively difficult, generally requiring low RF insertion loss and good high frequency performance to 10 GHz. The DFB arrays are generally common cathode or common anode, depending on the type of the substrate used to fabricate the devices. Described herein is an array with a common cathode or anode configuration using a MEMS based switch that shorts the selected laser to RF ground. With this topology, preferably the off-state capacitance should be low with the MEMS switch.

Abstract: A multisection quantum dot laser (7) comprising at least first (8) and second (9) sections, each section (8, 9) comprising a semiconductor substrate (2) comprising p (3) and n type (4) layers and a quantum dot layer sandwiched therebetween; the semiconductor substrate (2) comprising a back electrical contact in electrical contact with one of the p and n type layers and a tuning electrical contact (13, 14) in electrical contact with the other of the p and n type layers; the quantum-dot layers of the first (10) and second (11) sections being portions of the same quantum dot layer (12) forming a laser cavity.

Abstract: High power optical pulses generating methods and laser oscillators are provided. A light generating module generates seed optical pulses having predetermined optical characteristics. A spectrum tailoring module is then used to tailor the spectral profile of the optical pulses. The spectral tailoring module includes a phase modulator which imposes a time-dependent phase variation on the optical pulses. The activation of the phase modulator is synchronized with the passage of the optical pulse therethough, thereby efficiently reducing the RF power necessary to operate the device.

Abstract: The invention is directed to a method and an arrangement for stabilizing the average emitted radiation output of a pulsed radiation source. It is the object of the invention to find a novel possibility for stabilizing the average emitted radiation output of a pulsed radiation source which enables a reliable regulation even when there is no sufficiently reliable manipulated variable for influencing the emitted pulse energy (Ei). According to the invention, this object is met in that the individual pulse energy (Ei) of the current radiation pulse is measured, the deviation of the current individual pulse energy (Ei) from a previously determined target value (E0) is determined, and the pulse interval (?ti+1) preceding the triggering of the next radiation pulse is controlled depending on the magnitude of the deviation between the current individual pulse energy (Ei) and the target value (E0) of the pulse energy.

Abstract: A method and system for stabilizing a laser to a frequency reference with an adjustable offset. The method locks a sideband signal generated by passing an incoming laser beam through the phase modulator to a frequency reference, and adjusts a carrier frequency relative to the locked sideband signal by changing a phase modulation frequency input to the phase modulator. The sideband signal can be a single sideband (SSB), dual sideband (DSB), or an electronic sideband (ESB) signal. Two separate electro-optic modulators can produce the DSB signal. The two electro-optic modulators can be a broadband modulator and a resonant modulator. With a DSB signal, the method can introduce two sinusoidal phase modulations at the phase modulator. With ESB signals, the method can further drive the optical phase modulator with an electrical signal with nominal frequency ?1 that is phase modulated at a frequency ?2.

Abstract: A micro-opto-electro-mechanical systems (MOEMS) electro optical modulator (2) having an electrically tuneable optical resonator comprising an asymmetric Fabry-Perot etalon incorporating a mirror (10) resiliency biased with respect to a substrate (13) and moveable in relation thereto in response to a voltage applied there-between. The optical modulator (2) is capable of modulating electromagnetic radiation having a plurality of wavelengths. The modulator is adapted to modulate the transmission of short wave infrared radiation (SWIR), medium wave infrared radiation (MWIR) and long wave infrared radiation (LWIR) and the reflection of visible radiation. A spatial optical modulator having a plurality of said MOEMS optical modulators (2). A method of addressing said spatial optical modulator.

Abstract: Among others, RF receivers based on whispering gallery mode resonators are described. In one aspect, a photonic RF device includes a laser that is tunable in response to a control signal and produces a laser beam at a laser frequency. The RF device includes a first optical resonator structured to support a whispering gallery mode circulating in the first optical resonator, the optical resonator being optically coupled to the laser to receive a portion of the laser beam into the optical resonator in the whispering gallery mode and to feed laser light in the whispering gallery mode in the optical resonator back to the laser to stabilize the laser frequency at a frequency of the whispering gallery mode and to reduce a linewidth of the laser. The RF device includes a second optical resonator made of an electro-optic material to support a whispering gallery mode circulating in the optical resonator.

Abstract: Narrow surface corrugated gratings for integrated optical components and their method of manufacture. An embodiment includes a grating having a width narrower than a width of the waveguide on which the grating is formed. In accordance with certain embodiments of the present invention, masked photolithography is employed to form narrowed gratings having a desired grating strength. In an embodiment, an optical cavity of a laser is formed with a reflector grating having a width narrower than a width of the waveguide. In another embodiment an integrated optical communication system includes one or more narrow surface corrugated gratings.

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: Exemplary methods of maximizing a spur-free dynamic range (SFDR) or a gain of an electro-absorption modulator (EAM) are disclosed. At least one parameter in a set of design parameters for an EAM is varied. An SFDR of the EAM is determined in part by a first set of design parameters. A gain of the EAM is determined in part by a second set of design parameters. An output versus bias voltage transfer curve of the EAM is generated. An optimal SFDR bias voltage at which a maximum SFDR occurs for a given optical input power or an optimal gain bias voltage at which a maximum gain occurs for a given optical input power is programmatically determined based at least in part on the transfer curve.

Abstract: The present invention concerns a laser apparatus (200) comprising an external cavity laser (ECL) in which the optical signal is modulated by an electrical modulation signal with the purpose of modulating in frequency the laser output signal. The modulation in frequency produces in turn a modulation of intensity (power) of the laser output signal, also denoted amplitude modulation (AM). A method is described of control of the AM amplitude of a signal emitted by an ECL that comprises a gain medium (205), a phase element (206) with variable transmissivity induced by the modulation and a spectrally selective optical filter (209) and that selects and keeps the AM amplitude below a certain desired value or minimizes such value.

Abstract: A light source mode alignment device and method and a passive optical network system are provided. The device includes a laser and a temperature control unit connected to each other and further includes a signal processing unit. The laser converts an incident light into a current signal. The current signal is amplified and converted into a voltage signal via a transimpedance amplifier. Together with a modulation signal generated by the signal processing unit, the voltage signal adjusts a bias voltage of the temperature control unit.

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 a piston error controller for minimizing errors related to beam combination that may degrade the quality of the combined output beam. A piston 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. For each intermediate beamlet, the associated piston error contribution is recovered using a Hadamard decoder. A very small phase dither is also introduced to allow the sign or direction of the piston error to be recovered.

Abstract: A Vertical-Cavity Surface-Emitting Laser (VCSEL) is disclosed, comprising an optical cavity bounded by a top mirror and a bottom mirror, wherein the top mirror has multiple layers of alternating refractive index, of which the bottom three or more layers of the top mirror are deep oxidation layers having an increased oxidation length, a light emitting active region between the top mirror and the bottom mirror, and an aperture with tapered edges between the active region and the top mirror, wherein the aperture has a thickness, a taper length, an oxide aperture length, a taper angle, and an aperture opening diameter designed to reduce an optical mode's diameter without significantly increasing the optical mode's round trip scattering loss.

Abstract: A laser is disclosed including a gain section having a distributed feedback grating imposed thereon. An absorption section is embedded in the gain section such that the first and second portions of the distributed feedback grating extend on either side of the electro-absorption section. A controller imposes a substantially DC bias signal on the first and second gain electrodes and imposes a modulation signal encoding digital data on the modulation electrode to generate a frequency modulated signal. In some embodiments, the first and second portions are biased above the lasing threshold and the absorption section is modulated below the lasing threshold to modulate loss in the absorption section.

Abstract: A tunable pulsed laser includes a seed source and an optical circulator. The optical circulator includes at least a first port coupled to the seed source, a second port, and a third port. The laser also includes an amplitude modulator characterized by a first optical side and a second optical side. The first optical side is coupled to the second port of the optical circulator. The laser further includes a first optical amplifier characterized by an input end and a reflective end. The input end is optically coupled to the second side of the amplitude modulator. The laser additionally includes a tap coupler optically coupled to the amplitude modulator and characterized by a pre-determined split ratio. Moreover, the laser includes a first photo-detector optically coupled to the tap coupler and adapted to receive a portion of the seed signal transmitted through the amplitude modulator and to generate an output signal.

Abstract: A two-dimensional image display device using a Yb-doped clad pump fiber which is a rare-earth-doped fiber as a laser activation substance, whereby a peak of a fluorescence spectrum can be significantly increased as compared with a case of using an oxide crystal, and a variation width of an oscillation wavelength can be increased. Further, since the rare-earth-doped fiber is used as a fiber amplifier without providing laser mirrors at both ends thereof, control for a resonator length, which has been required in a conventional device (wherein an oxide crystal is used as a laser medium), is dispensed with, and thereby high-speed wavelength control is achieved, resulting in reduction in speckle noise when it is mounted on a two-dimensional image display device.

Abstract: The counting device includes: a signal counter that counts the number of half cycles of input signals during given counting periods; a signal half cycle measurement unit that measures the half cycles; a frequency distribution generator that generates a frequency distribution of the half cycles; a representative value calculator configured to calculate a representative value of a distribution of the half cycles; a correction value calculator configured to calculate a total number Ns and a total number Nwn so as to correct the number of the half cycles, wherein Ns represents the total of the number of the half cycles that are less than 0.5 times the represent value, and Nwn represents the total of the number of the half cycles that are equal to or greater than 2n and less than (2n+2) times the representative value.

Abstract: A tunable optical local oscillator is used for optical heterodyne signal detection using an electrooptic Mach-Zehnder modulator to produce a rapidly tunable optical signal from a tunable RF frequency generator. A combination of the Mach-Zehnder modulator and optical fibers for providing stimulated Brillouin scattering are used to suppress unwanted signals for providing a spectrally pure optical local oscillator waveform. Suppression of unwanted optical signals, up to 50 dB, generated by the Mach-Zehnder modulator is obtained, resulting in high spectral purity of the optical local oscillator waveform with an extended tuning range of the tunable optical oscillator equal to the operating bandwidth of up to 60 GHz of the Mach-Zehnder modulators.