Abstract: A scalable high power laser system includes a plurality of parallel connected modular power amplifier arms, coupled to a common master oscillator to provide a high average power laser system with a scalable output power level, particularly suitable for laser weapon systems with varying power level output applications. Adaptive optics devices are provided in order to provide pre-compensation of phase front distortions due to the modular amplifier arms as well as encode the wave front of the laser beam with a phase conjugate of atmospheric aberrations.

Abstract: In a tunable laser device a plurality of basically identical lasers are arranged adjacent to each other in a line or row on a common substrate. The lasers can be DFB-type and they have different emission wavelengths, obtained from e.g. different pitches of gratings which define the wavelengths of the respective lasers. The lasers can be activated to emit light independently of each other by supplying electrical current to contacts located on the top sides of the lasers. When a laser is activated, the other lasers are biased, so that lasers located at one of side of the active laser will be transparent to the emitted light, which can then travel from the lasers through an electrooptic modulator, and the lasers located at the other side will absorb the light. By controlling the temperature the wavelength of emitted light can be finely adjusted.

Abstract: Apparatus for providing a laser source optically coupled to an optical waveguide, such as an optical fiber, having a reflective grating positioned from the output facet of the laser source a distance equal to or greater than the coherence length of the laser source providing a portion of reflective feedback into the laser source optical cavity to maintain wavelength operation of the laser source in spite of changes in the laser operating temperature or drive current based upon coherence collapse in the laser operation. In cases where the fiber grating is positioned in the fiber within the coherence length of the laser source, intermittent coherence collapse, as opposed to continuous coherence collapse, is unavoidable. In cases where such a laser source is a pumping source for a solid state gain medium, such as an optical amplifier or laser having an active gain element, e.g.

Abstract: A solid state device used to modulate the intensity of reflected or transmitted light by modulating with an external voltage the optical thickness of a thin film ferroelectric placed in an etalon cavity is disclosed. The device is constructed by selecting a generally planar supporting substrate, preferably silicon or sapphire in order to be compatible with silicon integrated circuits. A dielectric stack consisting of alternating layers of different index of refraction materials, also specifically selected to be compatible with later growth of the thin film ferroelectric, is deposited thereon to form a partially reflective and partially transmitting mirror, followed by a transparent electrically conductive layer. The thin film ferroelectric is deposited on the conductive layer, followed by a second transparent conductive layer and a second dielectric stack. Leads are connected to the conductive layers and in turn to a voltage generator.

Abstract: The invention concerns a method of operating a laser diode (2) producing a beam (9) whose intensity is controlled by a control signal and which is directed along a first beam path (10) at the target surface (5), stray reflections from the target surface (50 which are unstable with respect to the diode (2) in time and/or space acting on the diode (2). An element (19, 28, 31, 37, 38) which is stable in time and with respect to the diode (2) in space is used to feed part of the light emitted by the diode back along a second beam path (11) to the active zone (42) of the diode (2) so that the diode (2) is kept in a state of coherence collapse.

Abstract: The frequency standard comprises a quantum absorber, a source of incident electro-magnetic radiation, a detector, a frequency difference controller, a spectrum controller and a frequency standard output. The quantum absorber has transitions including a first transition between a first lower quantum state and an upper quantum state, and a second transition between a second lower quantum state and the upper quantum state. The first transition and the second transition have energies that correspond to frequencies of &ohgr;1 and &ohgr;2, respectively. The lower quantum states differ in energy by an energy difference subject to a total a.c. Stark shift. The source of incident electro-magnetic radiation is arranged to irradiate the quantum absorber. The incident electro-magnetic radiation includes main frequency components at frequencies of &OHgr;1 and &OHgr;2, equal to &ohgr;1 and &ohgr;2, respectively, and additionally includes additional frequency components collectively having a spectrum.

Abstract: A control system for stabilizing the frequency of optical light output from a laser source including an oscillator for producing a modulation signal and a detection signal. An optical modulator receives the optical light output from the laser source and also receives the modulation signal and outputs a first and second modulator output signal. At least one filter is included for receiving the first modulator output signal and outputting a filtered signal having an amplitude that is a function of the change in frequency of the output light output from the laser source. A first optical detector receives the filtered signal and outputs a first electrical signal. A second optical detector receives the second modulator output signal and outputs a second electrical signal. A wavelength control circuit receives the first and the second electrical signals and the detection signal and outputs a control signal received by the laser source for adjusting the frequency of the optical light.

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: An optical transmitter having an automatic output controlling function converts monitor current of a laser into a voltage and detects an average value of the voltage. The average value is compared with a mark-space ratio outputted from a mark-space ratio detection circuit by a bias control circuit, by which a bias circuit is controlled. Meanwhile, the average value described above is divided by the mark-space ratio from the mark-space ratio detection circuit by an operation circuit, and a resulting value is compared with a reference voltage (Vref) and amplified by a pulse current controller. The pulse current driver is controlled with the amplified output of the pulse current controller. Finally, outputs of the pulse current driver and the bias circuit are added to drive the laser.

Abstract: A speckle reduction system divides pulses of coherent radiation into successions of temporally separated and spatially aberrated pulselets. One or more beamsplitters divide the pulses into the successions of pulselets that are circulated through delay lines. Spatial aberrators located along the delay lines modify wavefront shapes of the pulselets. Together, the temporal separation and spatial aberration of the pulselets produce a succession of different speckle patterns that can be averaged together within the integration interval of a detector to reduce speckle contrast.

Abstract: An optical transmitter (405) includes a distributed feedback semiconductor laser (100) operated in a linear regime below a threshold associated with stimulated Brillouin scattering to generate an optical signal. A resistor (125) or other heater is physically coupled to the semiconductor laser (100), and a modulated current source (120) drives the resistor (125) with a triangle waveform (300), thereby varying an optical wavelength of the optical signal such that the optical signal and a double Rayleigh backscattered signal are characterized, at the optical receiver (410), by different optical frequencies. As a result, interference generated by Rayleigh backscattering is minimized at the optical receiver (410).

Abstract: A laser polarization control apparatus includes a polarization modifying device, such as a liquid crystal variable retarder, and a controller. The polarization modifying device receives a laser beam and modifies the polarization of the laser beam. The controller, which is connected to the polarization modifying device, adjusts an input to the polarization modifying device in order to control modification of the polarization of the laser beam based on alignment of a structure to be processed by the laser beam. For example, the polarization of the laser beam may be rotated to correspond with the alignment of a link in a semiconductor device to be cut by the laser beam. The polarization modifying device is configured for incorporation into a laser processing system that produces the laser beam received by the polarization modifying device and that focuses the laser beam modified by the polarization modifying device onto a workpiece that includes the structure to be processed by the laser beam.

Abstract: An integrated laser/modulator (“ILM”) operating with reduced chirping is formed on a single semiconductor substrate. A reduction in chirping and any resultant wavelength dispersion is realized by precisely controlling the length of a window region incorporated in the ILM in order to isolate the ILM's active regions from any residual reflections.

Abstract: A novel device and method of beam steering for semiconductor lasers or optical amplifiers is disclosed. The method of the present invention achieves high signal extinction ratios, high speed, low chirp modulation by biasing a multi-lateral mode beam steering section. The device of the present invention comprises an active single vertical and lateral mode optical waveguide, a multi-lateral mode waveguide, and a mode converter. The mode converter efficiently couples output from an active single mode waveguide to two or more modes of a multi-lateral mode waveguide. Two guided modes arrive at a device facet with a particular intermodal phase difference based on initial mode phasing, multi-lateral mode waveguide length and modal dispersion properties, and facet angle. Beam steering is achieved through carrier antiguiding effect by injecting current into the multi-lateral mode waveguide from the mode converter thus changing the intermodal dispersion.

Abstract: A tunable semiconductor laser comprises a gain section having an MQW active region, a uniform pitch grating DFB region, and first waveguide. A composite reflector, including a second MQW region and a second waveguide, forms a cavity resonator with the DFB region. A tuning voltage applied to the composite reflector induces refractive index changes, thereby allowing the center wavelength to be altered.

Abstract: A multi-wavelength Raman radiation source is disclosed. The source receives pump radiation at a given wavelength, e.g., 1100 nm, and has outputs at two or more longer wavelengths, e.g., 1450 nm and 1480 nm. The cascaded Raman resonator comprises, for each desired output wavelength, an optical cavity formed by a high reflectivity grating and a low reflectivity grating, with both having the same center wavelength, equal to the desired output wavelength. Multi-wavelength Raman radiation sources have a variety of applications, e.g., they can advantageously be used in a remotely pumped optical fiber communication system.

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: A laser transmitter used in an optical communication system provides automatic compensation/stabilization of CNR (carrier to noise ratio) and OMI (optical modulation index) in conditions that would have caused these parameters to change if the compensation circuitry was not employed. The compensation circuitry is an open loop that operates in conjunction with a conventional APC (automatic power control) loop. When certain parameters change (i.e., temperature, laser aging, intentional change in optical power) they will affect the laser DC current (either directly or because of the existence of the APC loop) and as a result the CNR/OMI will change. The compensation circuitry senses the change in the laser DC current and changes the modulating current to the laser as required to minimize changes in CNR/OMI.

Abstract: A pulse width modulation and intensity modulation signal generating unit, based on input data, performs pulse width modulation and intensity modulation and generates a light emission instruction signal. An error amplifier forms a negative feedback loop together with a semiconductor laser and a light reception device which monitors light output of the semiconductor laser, the error amplifier controlling forward current of the semiconductor laser so that a light reception signal proportional to the light output of the semiconductor laser is equal to the light emission instruction signal. A current driving unit causes a driving current, according to the light emission instruction signal, to flow through the semiconductor laser as the forward current thereof, the driving current being generated so as to control driving of the semiconductor laser with a current of the difference or sum with the control current of the negative feedback loop.

Abstract: In order to eliminate noise of a solid state laser apparatus generating a blue light wave, the solid state laser apparatus comprises a solid state laser light source, an optical modulator having a light modulating function and outputting the modulated light therefrom as a desired light output, a photo-detector converting one part of output light from the solid state laser light source to an electrical signal, an electrical circuit detecting a noise component from the electrical signal and moving the phase of an electrical signal corresponding to the noise component, and a controller for applying the output signal of the electrical circuit to the optical modulator so as to substantially eliminate light of the blue light wave corresponding to the noise component so as to provide the desired light output from the optical modulator.

Abstract: An integrated laser/modulator ("ILM") operating with reduced chirping is formed on a single semiconductor substrate. A reduction in chirping and any resultant wavelength dispersion is realized by precisely controlling the length of a window region incorporated in the ILM in order to isolate the ILM's active regions from any residual reflections.

Abstract: A laser diode drive circuit comprising a laser diode; a drive pulse current source for emitting light or not emitting light of the laser diode according to an input signal; and a biasing unit for optimally operating the laser diode, the biasing unit having a bias voltage source for applying a bias voltage to the laser diode, which bias voltage can feed an optimum bias current to the laser diode. The laser diode drive circuit can maintain a bias current at a predetermined value with high precision and with high stability.

Abstract: A laser controller (12) that has particular application for controlling a solid state diode laser (10) including a series of gain modules and associated diode arrays. The laser controller (12) includes a control console (44) including a touch screen (46) that allows a laser operator to interface with the controller (12) to control the laser (10) and laser parameters. The control console (44) includes a target monitor (50) that allows the operator to view the laser beam at a reduced beam intensity for alignment and beam quality purposes. The laser controller (12) further includes a computer (14) having a counter circuit (20) that outputs a signal to set the pulse width and pulse rate of the laser beam output. This control allows the laser beam output to be ramped from one beam intensity to another beam intensity during a laser operation.

Abstract: A programmable acoustooptic device including an elastooptic medium configured to receive an input optical pulse and an acoustic wave; an acoustic transducer configured to generate the acoustic wave in the elastooptic medium along a defined direction; and a programmable circuit coupled to the acoustic transducer and configured to program at least one of a frequency modulation and phase modulation of the acoustic wave, whereby the acoustic transducer generates a modulated acoustic wave, wherein an output optical pulse is generated and is a convolution of the input optical pulse with the modulated acoustic signal.

Abstract: A current driver circuit for a vertical cavity surface emitting laser (VCSEL), flip-chip bonded to a CMOS device. In a preferred embodiment, the circuit includes only two transistors. Specifically, a P-channel metal-oxide semiconductor (PMOS) source supplies a current under the control of a tuning voltage (Vtune) while an N-channel metal-oxide semiconductor (NMOS) transistor acts as a high-speed current shunt that modulates the current flowing through the VCSEL, and hence its emitted power.

Abstract: A fiber laser system including multiple fiber lasers fabricated to emit at respective different wavelengths when optically pumped by radiation at a pump wavelength. A pump laser emits the pump radiation and pumps one or more of the fiber lasers. The outputs of the fiber lasers are recombined onto a transmission fiber, preferably for use in a wavelength-division multiplexing (WDM) telecommunication system. In one set of embodiments, an optical switch switches the pump radiation to only one of the fiber lasers. A second switch controlled in correspondence to the first switch or a passive combiner, preferably a wavelength-division multiplexer, directs the output of the lasing fiber to an optical output path. In another embodiment, the one pump laser simultaneously pumps all the fiber lasers. One or more pump laser may be placed in parallel, and their outputs are combined. The parallel pump lasers may either be individually activated for redundancy or simultaneously operated for higher power.

Abstract: Techniques for controlling the operation of a laser diode to maintain optimum operating characteristics (i.e., fairly constant output power and extinction ratio) despite the fact that the threshold current and slope efficiency vary greatly over a the desired range of operating temperature. A laser driving circuit includes a bias current generator, a temperature-dependent modulation current generator, and a switching element for switching the modulation current on and off in accordance with a desired input pattern. The modulation current is caused to vary with temperature in a manner that compensates for the fact that the laser diode's slope efficiency varies with temperature.

Abstract: A driving method of the present invention drives a semiconductor laser which is provided with at least first and second electrodes through each of which current is injected into the semiconductor laser. Varying current is injected through the first electrode when the frequency of the varying current is in a high frequency band. Varying current is injected through the first electrode while phase-shifted current, whose phase is shifted relative to the varying current, is injected through the second electrode, when the frequency of the varying current is in a low frequency band which is lower than the frequency of the high frequency band. Feedback-control may be performed for controlling a ratio between amplitudes of the modulation current and the phase-shifted current based on a light output from the semiconductor laser.

Abstract: Laser systems, and optical elements for laser systems, are disclosed for providing a pumped laser light with improved output efficiency while having simple construction and simple alignment adjustment. A pump light flux from a diode pumping laser irradiates and thus pumps a solid-state laser crystal. The irradiation by the pump light flux is coaxial with an output laser beam produced by the laser crystal. The pump light flux is conducted by an optical element, preferably frustoconical in shape with an entrance face larger than an exit face, that functions as a light funnel. The entrance face is disposed proximal to the pumping laser 11, and the exit face is disposed proximally to the laser crystal 14. A portion of the pump light flux entering the entrance face passes through the optical element without being reflected by a side surface of the optical element. The remaining pump light flux reflects at least once by the side surface during passage through the optical element.

Abstract: The bias point of an electro-optic modulator, such as an Mach-Zender modulator, is automatically controlled. A pilot signal, preferably two pilot tones at different frequencies, is applied to the modulator. The output of the modulator then contains various components resulting from the pilot signal. An error signal is generated, preferably coherently, based on one of these components, termed the pilot component, which preferably is located at the difference frequency of the two pilot tones. A bias signal which controls the bias point of the modulator is adjusted based on the error signal. The coherent generation of the error signal facilitates feedback loops based on phase and/or amplitude control and also supports locking the electro-optic modulator to a bias point with a preselected slope (either negatively or positively sloping).

Abstract: A semiconductor laser is disclosed, which realizes a continuous oscillation in a fundamental transverse mode at a low operating voltage by a transverse mode control. This semiconductor laser is fabricated by forming successively the following layers on a sapphire substrate 10 in the order an n-type GaN contact layer, an n-type GaAlN cladding layer 13, an MQW active layer 16, a p-type GaAlN cladding layer 19, wherein the laser comprises a double heterostructure including a ridge in the shape of a stripe formed in the cladding layer 19 and a light confining layer 20 formed in a region except the ridge portion of the cladding layer 19 on the double heterostructure, wherein a refractive index of the light confining layer 20 is larger than that of a p-type GaAlN cladding layer.

Abstract: A mode-locked semiconductor laser includes a gain region formed from a semiconductor gain material of two or three dimensional carrier confinement structure having a size on the order of a thermal de-Broglie wavelength, the size of the semiconductor of the carrier confinement structure being controlled such that the gain spectrum has discrete peaks at a frequency period which is an integer power of the reciprocal of the round-trip time of light in the optical resonator.

Abstract: A laser arrangement for recovering a clock from a modulated optical input signal (S.sub.o) has, between a resonator mirror (21) for launching the input signal and a resonator mirror (42) for coupling out the recovered clock (T), a bidirectional optical transmission channel (3) having at least two nonlinear optical amplifiers (2, 4) and a demultiplexer (6) between the amplifiers. The arrangement is operated as a mode-locked laser and is suitable for optical repeaters.

Abstract: A technique for characterizing laser chirp utilizes an optical fiber and its inherent interferometric properties. An RF modulating signal is applied to the laser, where the modulated output signal thereafter propagates through a conventional optical fiber. A photoreceiver and spectrum analyzer are coupled to the opposite end of the optical fiber. By adjusting the power of the applied RF signal, the maximum IIN can be determined. The laser chirp can then be calculated by dividing the measurement frequency by the modulation current associated with the maximum IIN value.

Abstract: In one embodiment, an optical transmitter, which has a modulator disposed between an pair of optical amplifiers, exhibits reduced carrier-to-noise ratio and relatively high powers. In another embodiment, an optical amplifier is disposed between the laser carrier source and the modulator, but the post-modulator amplifier is omitted. Application of the transmitters to analog systems (e.g., CATV) and digital systems is described.

Abstract: A harmonic generator laser system which features a distributed Bragg reflector (DBR) or distributed feedback (DFB) tunable diode laser coupled to a quasi-phase matched (QPM) waveguide of optically nonlinear material. Tuning of the DBR laser may be achieved either thermally or via current injection, or both, halving the wavelength of a red laser into the visible blue spectral band. Thermal tuning may provide a coarse tuning adjustment, while injected current may provide fine tuning accessible to a user. Separately or in combination with current tuning, a modulation signal may be applied to the DBR laser for achieving an intensity modulated or a pulsed output. In another embodiment, modulation may be achieved by frequency modulation of the laser. A very compact tunable blue laser is formed. In yet another embodiment a double clad fiber amplifier is disposed between the tunable laser and the waveguide.

Abstract: A semiconductor laser device in which a semiconductor laser emitting laser light and a light modulator modulating the laser light are integrated on a compound semiconductor substrate, includes a hole trapping layer for suppressing a reactive current that is generated when the semiconductor laser is operated and that does not contribute to laser oscillation. The hole trapping layer has a first region in the semiconductor laser and a second region in the light modulator. The hole trapping layer has a high carrier concentration and a low resistance and is discontinuous between the semiconductor laser and the light modulator, so that isolation between the laser and the modulator is increased, whereby a high-frequency signal applied to the light modulator is prevented from flowing through the hole trapping layer into the laser.

Abstract: A method for biasing a semiconductor laser (12) at the threshold level of the semiconductor laser (12). The method includes applying pilot tone signals having the same frequency to a bias current and a drive current of the semiconductor laser (12). A lateral detector (13) generates a photocurrent from spontaneous emissions of the semiconductor laser (12). Further, the method includes biasing the semiconductor laser (12) using a pilot tone signal of the photocurrent.

Abstract: The present invention relates to A drive circuit can stabilize a bias voltage of an optical modulator to realize long distance transmission by preventing degradation of waveform, even if there is a dispersion on a characteristic of an electro-absorption modulator according to temperature and a secular change. The drive circuit supplies a driving voltage to an electro-absorption modulator which adsorbs a carrier light, depending on the driving voltage and outputting an intensity-modulated signal, and a peak value detector for detecting a peak value of a voltage at an anode of the electro-absorption modulator, and a bias current supplying circuit for supplying a bias current to control the driving voltage according to a difference between the peak value detected by the peak value detector and a predetermined value.

Abstract: An improved wavelength tunable transmitter comprises a waveguide grating router coupled to a truncated Mach-Zehnder interferometric modulator. Light from the second order Brillouin zones of a waveguide grating router having substantially the same phase are captured and coupled to first and second transmission paths comprising the truncated Mach-Zehnder interferometer, the transmission paths then being altered relative to each other and recombined to produce a modulated output signal. With this configuration, a compact tunable transmitter is provided exhibiting bandwidth and chirp control features comparable with those of a traditional Mach-Zehnder interferometer.

Abstract: A method for doping semiconductors used for far infrared lasers with non-hydrogenic acceptors having binding energies larger than the energy of the laser photons. Doping of germanium or silicon crystals with beryllium, zinc or copper. A far infrared laser comprising germanium crystals doped with double or triple acceptor dopants permitting the doped laser to be tuned continuously from 1 to 4 terahertz and to operate in continuous mode. A method for operating semiconductor hole population inversion lasers with a closed cycle refrigerator.

Abstract: A laser array for determining the concentrations of gases. A simply acting device and a corresponding process are provided, which make possible a high signal resolution by reducing the interferences without prolonging the measurement time. The interferences occurring in the laser array are reduced by the laser source being set to perform longitudinal oscillations in the direction of the optical axis. These oscillations preferably have a sinus or sawtooth shape, and a frequency in the range of 10 to 1,000 Hz that does not otherwise occur in the laser array and an oscillation amplitude corresponding to one fourth to a multiple of the wavelength of the radiation of the laser source.

Abstract: The present invention relates to a white pulse source that produces spectrally shaped white pulses of a constant optical output power over a wide wavelength range. The white pulse source includes a pump pulse source for generating pump pulses with a center wavelength .lambda.0 and a waveguided nonlinear optical medium with a length L. The waveguided nonlinear optical medium is characterized by two properties: the first property is that chromatic dispersion D(.lambda.0,z) at the center wavelength of pump pulses in ps/nm/km is positive at an input end of said waveguided nonlinear optical medium, where z=0, and decreases towards an output end. The second property is that said chromatic dispersion D(.lambda., z) has a maximum value D(.lambda.p(z), z) at a peak wavelength .lambda.p(z) within a range of propagation distance given by L1.ltoreq.z.ltoreq.L where 0.ltoreq.L1<L, and that said chromatic dispersion D(.lambda., z) has two zero-dispersion wavelengths, .lambda.1(z) and .lambda.2(z), where D(.lambda.

Abstract: A tunable semiconductor laser comprises a gain section having an MQW active region, a uniform pitch grating DFB region, and first waveguide. A composite reflector, including a second MQW region and a second waveguide, forms a cavity resonator with the DFB region. A tuning voltage applied to the composite reflector induces a quantum confined stark effect, thereby allowing the center wavelength to be altered. A pre-chirp signal applied the composite reflector reduces signal distortion in fiber optic systems.

Abstract: A laser beam generating device which, by addition of a simplified structure, can enlarge the spectral width of the laser light and lower the coherence to a moderate value. The laser light generating device includes a first laser light source 31, a second laser light source 32, phase modulation units 34, 35 for phase-modulating the beams from the light sources with a sole frequency component or plural frequency components, and an additive frequency generating unit 33 for producing a light beam of the shorter wavelength based on the wavelength of the light phase-modulated by the phase modulation units 34, 30. The fundamental wavelength laser light generated by the first laser light source 31 is phase-modulated by the phase modulation unit 34 based on a pre-set modulation amplitude and the modulation frequency so as to be enlarged in spectral width before being incident on the additive frequency generating unit 33.

Abstract: A laser transmitter based on a star coupler includes a separate controlled output port. An interferometric modulator is incorporated inside a laser cavity by means of a star coupler and enables modulation of the laser signal, independent of the means of wavelength selection used to determine the frequency of the laser.

Abstract: A laser apparatus capable of emitting a laser beam upon wavelength conversion and intensity modulation, which comprises a fundamental wave resonance means comprising a light emitting part, an optical resonator comprising mirrors sandwiching the light emitting part and capable of laser resonating, and a modulation-conversion means set inside said optical resonator, said light emitting part being a semiconductor light emitting element or a laser medium, said modulation-conversion means converting, by a nonlinear optical effect, a fundamental laser resonance wavelength light, and phase modulating said light by an electro-optical effect, and a modulation part of said modulation-conversion means comprising electrodes for application of a modulation voltage.

Abstract: In a semiconductor laser for analog modulation, intermodulation distortion at high temperatures and/or at high outputs is reduced. In a DC-PBH semiconductor laser, the width (Wm) of the electrode mesa 11 is set at 10 .mu.m or less, and the width of each recombination layer 2 is set at 0.1 .mu.m or more. Further, the distance between one end of the active layer 1 and one end of each current-blocking layer 5 is set at 0.01 .mu.m to 0.5 .mu.m.

Abstract: A multichannel acousto-optic modulator (MCAOM) is described which uses a crystal with a plurality of mounting faces for acoustic transducers. The mounting faces are oriented so that the acoustic transducers mounted thereon generate acoustic fields which intersect the incident laser beam at a common angle, i.e., the Bragg angle. A two channel MCAOM uses two transducers. Extension to any higher number of channels follows accordingly. Energizing any of the transducers causes a corresponding first order beam to be diffracted out. Since the acoustic field for each transducer intersects the incident beam with a unique orientation, each first order beam is diffracted out on a unique axis. A system utilizing an MCAOM has electronic means for controlling the driving signals to the transducers to control each channel as required by the application. Amplitude and frequency modulation of the driving signals allows the intensity and angle of the beams to be controlled.