Abstract: A multi-element, uniformly pumped laser includes a plurality of laser medium elements, a pumping means, a highly reflective reflector and an output coupler. The pumping means includes at least one pumping element which simultaneously excites at least two of the laser medium elements. An alternate uniformly pumped ring laser and an alternate uniformly pumped laser amplifier are also disclosed.

Abstract: A wavelength-tunable light source is provided, by which an output beam of a stable wavelength can be obtained even if a driving condition of the optical amplifier is changed, and in which stable wavelength tuning without mode hopping can be performed.

Abstract: The invention provides a compactly built solid state laser, which can be pumped by high power semiconductor laser diodes and uses two or more laser crystals as the laser gain or amplification media, which crystals can also contain the resonator mirrors. As desired per the invention, linear, monolithic folded or ring-shaped laser resonators can be formed to provide very efficient production of frequency doubled laser radiation.

Abstract: The invention relates to a multi-channel RF-excited gas laser device which has an elongate tubular dielectric housing 1. The housing has a common elongate ground electrode 2 therein and a plurality of laser channels 4 defined within and extending along the ground electrode 2 adjacent to an interior surface 3 of the dielectric housing. A laser gas is provided within the dielectric housing and a plurality of RF electrodes 7 are disposed adjacent to and extending along an external surface 8 of the dielectric housing 1. Each RF electrode 7 is disposed in registration with one of the laser channels 4.

Abstract: A cylindrically shaped gain medium for a laser resonant cavity. The gain medium has an outer cylindrical side surface and two opposing end faces. An annular groove is formed in the side surface. An energy source excites the gain medium to create a laser beam inside the cavity. The laser beam passes longitudinally through the gain medium. The annular groove defines an annular aperture inside the gain medium for the laser beam. The annular aperture has a diameter that is smaller than a diameter of the side surface and the end faces.

Abstract: A laser with high average power, high repetition rate, ultra-short pulsewidth, and excellent beam quality is described. This is achieved by the use of high power diodes used to uniformly pump an improved Nd:YAlO.sub.3 crystal, resulting in a beam with excellent quality. In addition, a beta-barium borate (BBO) crystal, used in conjunction with drift step recovery diodes (DSRDs), forms a high speed optical switch which can be used to cavity dump the laser.

Abstract: An electric discharge gas laser having a laser cavity in which is contained a laser gas and a fan for circulating the laser gas. The fan is supported by an active magnetic bearing system and driven by a brushless DC motor in which the rotor of the motor and at least two magnetic bearings sealed within the gas environment of the laser cavity and the motor stator and the coils of the bearing magnets are located outside the gas environment.

Abstract: A laser-diode-pumped solid state laser includes a Fabry-Perot resonator having a pair of resonator mirrors. A holder is provided with a pair of mirror mounting portions respectively having mirror mounting surfaces which are spaced from each other in the direction of the optical axis of the resonator and extend to intersect the optical axis of the resonator, and with connecting portion which is formed integrally with the mirror mounting portions to connect the mirror mounting portions. The resonator mirrors are fixed to the mirror mounting portions with their light transmissive end faces bonded to the mirror mounting surfaces of the holder.

Abstract: Microlaser cavity and externally controlled, passive switching, pulses solid microlaser including a saturable absorber 46 and a device (60, 62) for introducing a beam 56 into the microlaser cavity initiating or starting saturation of the saturable absorber.

Abstract: An electron beam pumped semiconductor laser which includes a substrate, an optical gain structure provided on the substrate, the optical gain structure being comprised of a plurality of alternating quantum well layers and isolation layers, the quantum well layers being spaced apart from one another by respective, intervening ones of the isolation layers by a sufficient distance to substantially isolate the quantum well layers from one another, and a first reflective layer provided on a first surface of the optical gain structure. With this construction, the quantum well layers are quantum mechanically uncoupled. Further, the optical gain structure has a total thickness which is sufficient to enable the optical gain structure to be coupled to excitation of an electron beam produced by an electron beam pumping device and directed through the first reflective layer and incident upon the optical gain structure.

Abstract: Disclosed is an optical amplification device comprising an amplifier medium inserted between two mirrors and an optical pumping source. The mirrors are confocal mirrors whose focal plane is located in the vicinity of the center of the non-linear medium. This medium has a match-stick shape with a large axis in one direction forming an angle alpha/2 with the optical axis of the cavity defined by the two mirrors and the amplifier medium. This architecture enables an incident optical wave to pass several times within the amplification device leading to an increase in the performance characteristics of said device.

Abstract: Second Harmonic microchip laser producing coherent blue wavelengths tunable from 430 nm to 480 nm is disclosed. The microchip laser is formed by an optical contact of two crystal surfaces with a small gap, which provides a stable laser performance. The same technology is also applied to generate other blue, UV, and infrared lasers.

Abstract: A control system for an etalon arrangement 4, in an optical transmission system involves applying a dither to a laser 1 upstream of the arrangement, monitoring the output of the arrangement, and using a control means 3 to lock the laser frequency to the etalon arrangement response, or vice versa. The control means operates on the basis of a ratio of derivatives of the monitored output with respect to wavelength, to enable locking to a point on the response curve, independent of power variations.

Abstract: An optical chamber for use in a laser or other optical device includes a hollow container with holes at opposite ends. A fixed mirror is sealed to the housing and overlies one hole, whereas a movable mirror is sealed to the housing by a flexible seal such as an O-ring interposed between the mirror and the housing. A variable force actuator such as a piezoelectric element biases the movable mirror against the seal. By varying the force applied by the actuator, the movable mirror can be moved towards and away from the fixed mirror to vary the path length through the chamber. The chamber can provide a low cost tunable gas laser.

Abstract: The multiple emitters laser diode assembly comprises a laser diode bar for emitting a laser beam. The laser diode bar comprises a plurality of emitters aligned with respect to each other in a same plane of emission. A graded-index elongated fiber microlens is transversely set at a given distance in front of the laser diode bar for controlling the divergence of the beam. The microlens has an axis of symmetry substantially intersecting the optical axis of each emitter. A mount is provided for positioning the microlens with respect to the laser diode bar. Alternatively, the assembly may comprise a laser diode array for emitting the beam. The laser diode array comprises a plurality of substantially parallel rows of emitters with a substantially regular period between them. An array of graded-index elongated fiber microlenses is positioned substantially parallel to the rows. Each microlens corresponds to one of the rows for collimating the beam generated thereby.

Abstract: A high power laser source having a preselected broad bandwidth, including a master oscillator providing a single-mode laser beam, a resonant electro-optical modulator and a source of radio-frequency (rf) modulation voltage, to produce a modulator output beam having sidebands spaced on each side of the nominal frequency of the single-mode laser beam. The bandwidth and the number of modes may be varied by controlling the voltage applied to the modulator. At least one additional modulator in series with the first provides for the addition of other sidebands overlaying those generated with just one modulator. In another embodiment of the invention, the modulator is installed in a PC MOPA (phase conjugated master oscillator power amplifier) configuration to provide modulation only on the return path of the beam from a phase conjugation device having a stimulated Brillouin scattering (SBS) medium.

Abstract: An improved lens structure is provided which reduces the scattering and/or reflection losses in an optical cavity. The lens comprising at least a first, second and third lens layer arranged vertically, the first and third lens layers being oxidized in first and third oxidized regions adjacent to first and third non-oxidized regions, the second layer disposed between the first and third layers and comprising a non-oxidized semiconductor material, the first and third non-oxidized regions comprising a semiconductor material, each of the oxidized regions having an aluminum contents greater than 20%; and appropriately spacing the first lens layer from the third lens layer to reduce the scattering and/or reflection losses in an optical cavity.

Abstract: A laser or laser amplifier apparatus has a diode pump source producing a polarized pump beam. A laser head includes a gain medium that produces an output beam. One or more optical fibers are coupled to the diode pump source and deliver the pump beam to the laser head. A depolarization device is coupled to the diode pump source, laser head or optical fiber and produces an depolarized pump beam. By depolarizing the output beam, movement, including rotation, of the pump source does not comprise the output beam produced from the laser head.

Abstract: A short wavelength light source mainly comprises a semiconductor laser for pumping a laser medium, a birefringence filter for controlling or stabilizing the waveform by applying an optical feedback to the semiconductor laser to feed back only light of specific wavelength, lens systems for focusing the pumping light, and an optical resonator composed of a laser medium formed of Nd:YAG doped with 1% of Nd and a nonlinear optical element formed of KNbO.sub.3. The birefringence filter is structured as a Lyot filter, and is composed of a birefringence element made of 2 mm thick non-doped YVO.sub.4, a polarizer, and a birefringence element made of 4 mm thick non-doped YVO.sub.4.This constitution realizes a short wavelength light source achieving a single longitudinal mode oscillation while maintaining a high output, small in size, superior in efficiency, and excellent in wavelength stability.

Abstract: In order to improve an oxygen-iodine laser comprising a reaction unit for the generation of a gas stream composed of excited oxygen by chemical reaction between a reaction liquid and a reaction gas, a steam trap with a condensation chamber, in which steam entrained by the gas stream is condensed onto cold surfaces, an iodine injector, which injects iodine into the gas stream to generate a laser-active gas mixture, and a laser resonator with the laser-active gas mixture flowing through it, in such a way as to obtain a gas stream as free from steam as possible using the simplest possible means, it is proposed that the cold surfaces for separation of the steam are formed by liquid surfaces of a condensation liquid moved in the condensation chamber.

Abstract: A narrow band excimer laser capable of easily adjusting the rotation of the laser beam by an image rotator provided between a laser chamber and a grating and on the laser beam optical axis. The image rotator is supported with freedom of rotation on the laser beam optical axis and rotates the laser beam about the optical axis so that the plane containing the direction in which the width of the laser beam incident upon the beam expander is narrower is parallel with the plane containing the beam-expansion direction of the beam expander, and the beam expansion direction of the laser beam incident upon the grating is perpendicular to the direction of the grooves of the grating. With this arrangement, a laser beam of narrowed bandwidth can be obtained with high efficiency.

Abstract: A rare-earth doped, lithium niobate, diffusion Bragg reflector laser having a simplified structure and improved efficiency is disclosed. The laser has a pump source, a wavelength division multiplexer, a substrate of lithium niobate doped with at least one rare earth element and having a feedback element, and a grating reflector. The grating reflector is formed from portions of an optical fibre and abuts one end of the doped substrate, such that the grating reflector and the feedback element of the doped substrate form a cavity for the laser. The doped substrate may include phase or amplitude modulators for FM or AM mode-locking operation.

Abstract: A longitudinally-cooled laser element assembly comprises an optically transparent heat sink (OTH) coupled to a laser element and a heat sink. An etalon structure including a first flat surface and a second, substantially parallel flat surface is formed in the laser element and/or the OTH. In some embodiments, a balanced etalon is provided by forming a reflector on the second flat surface of the etalon that has a reflectivity approximately equal to the Fresnel loss at the interface between the OTH and the laser element. In some embodiments the laser element assembly includes a second OTH coupled to the laser element at a second interface, thereby defining a second Fresnel loss. Preferably, the second OTH has an index of refraction substantially equal to the index of refraction of the first OTH, so that said first and second Fresnel losses are approximately equal and a balanced etalon is formed. In some embodiments the laser element comprises a solid-state gain medium.

Abstract: A compact diode pumped solid state slab laser gain module 20 is described. The laser gain module comprises a ceramic housing 22, a laser gain medium 24 disposed in the laser cavity 22, and an optical pumping source. The housing is preferably composed of alumina which provides thermal and structural stability at high temperatures to maintain beam alignment and eliminates parasitic oscillations. The laser gain medium is preferably a slab of crystalline Nd:YAG. Diode laser arrays 48, 50 are provided to pump at least one side face 30, 32 of the laser gain medium. Each diode laser array 48, 50 is mounted to a manifold 40, 42 preferably formed of a plastic, non-contaminating material. The laser gain module comprises a simplified cooling distribution for cooling the laser gain medium to produce a substantially uniform temperature distribution between its top and bottom faces, and for cooling the diode laser arrays.

Abstract: The present invention relates to a highly repetitive laser employing a rotating wedge, and more specifically, a laser employing a rotating wedge which can provide a laser beam having a uniform spatial intensity profile with a high repetition rate. The highly repetitive laser of the invention is characterized by positioning a rotating wedge between a main resonator and a focusing lens to change the point in which a laser beam emitted from the main resonator is focused, in a laser which comprises a main resonator consisting of a laser medium, a passive Q-switching material and partially reflective mirrors and an auxiliary resonator consisting of a focusing lens and a cell.

Abstract: A high power solid state laser has a solid state laser medium with two ends and a longitudinal axis, at least one laser diode configured to end pump the laser medium, a resonator in optical alignment with the laser medium, a transparent and thermally conductive end cap disposed at each end of the laser medium and in thermal communication therewith, and at least one heat sink in thermal communication with the end caps. The end caps and the heat sink(s) cooperate to effect heat flow from the laser medium such that a substantial component of the heat flow is along the longitudinal axis of the laser medium, thus mitigating undesirable transverse temperature gradients within the laser medium and enhancing average power output therefrom.

Abstract: A micro-optical resonator type organic electroluminescent device utilizing an organic electroluminescent material high in emission efficiency but broad in emission spectrum width, has a narrow half bandwidth in the emission peak and a superior forward directivity and an excellent monochromaticity in light not separate into components, wherein a micro-optical resonator is formed by a multi-layered mirror and a metal mirror. The optical length of the micro-optical resonator, calculated from the total thickness and the refractive index of a transparent conductive layer and a luminous layer placed between the multi-layered mirror and the metal mirror and also from the light penetration depth into the multi-layered mirror, is 1.5 times the wavelength of a desired light emitted from the device, and the desired light is set on the short wavelength side of the emission spectrum of the electroluminescent material.

Abstract: A method and apparatus for exchanging energy between relativistic charged particles and laser radiation using inverse diffraction radiation or inverse transition radiation. The beam of laser light is directed onto a particle beam by means of two optical elements which have apertures or foils through which the particle beam passes. The two apertures or foils are spaced by a predetermined distance of separation and the angle of interaction between the laser beam and the particle beam is set at a specific angle. The separation and angle are a function of the wavelength of the laser light and the relativistic energy of the particle beam. In a diffraction embodiment, the interaction between the laser and particle beams is determined by the diffraction effect due to the apertures in the optical elements. In a transition embodiment, the interaction between the laser and particle beams is determined by the transition effect due to pieces of foil placed in the particle beam path.

Abstract: An optical fibre distributed feedback laser comprises an amplifying optical fibre (50) operable to provide optical gain at a lasing wavelength, in which a diffraction grating (30) is disposed on at least a portion of the amplifying optical fibre to provide distributed optical feedback for sustaining lasing action at the lasing wavelength.

Abstract: A laser system in which an intense laser beam of a predefined pumping wavelength traverses a non-linear material, such as crystalline lithium niobate, that has been impressed with one or more quasi phase matching (QPM) gratings is disclosed. Quasi phase matching compensates for the dispersion or birefringence in a non-linear material by modulating the non-linearity with the proper period such that the different wavelengths involved in the non-linear process stay in phase over a long interaction length. The first QPM grating promotes the parametric generation of a resonant signal whose wavelength is determined by the grating period. According to the invention, either a second QPM grating impressed in the same medium or a different order of the first QPM grating promotes the non-linear interaction between the resonant signal and another optical signal traversing the non-linear material.

Abstract: A laser includes a laser medium, a light source for emitting light which pumps the laser medium, a pair of mirrors which are disposed on opposite sides of the laser medium and form a resonator, an etalon which is disposed in the resonator in order to make the oscillation mode of a laser beam a single longitudinal mode and a nonlinear optical crystal which is disposed in the resonator and converts the laser beam to a second harmonic. The effective thickness t of the etalon satisfies the condition that 2t(n.sub.SH -n.sub.FM)/.lambda..sub.SH is substantially an integer wherein .lambda..sub.SH represents the wavelength of the second harmonic, n.sub.FM represents the refractive index of the etalon for the fundamental wave and n.sub.SH represents the refractive index of the etalon for the second harmonic.

Abstract: An asymmetric feedback structure in a ring laser produces essentially unidirectional lasing. The structure can be dynamic to permit directional control, or can be passive to provide unidirectional lasing in a predetermined direction. Dynamic control is obtained by a dielectric stack in the laser cavity, the stack including multiple layers having complex impedances for reflecting incident light. The amount and direction of reflection is controlled by varying the refractive indices or the absorption coefficients of the materials in the layers to produce cross-coupling for one direction which is different from the other direction. Passive control is obtained by introducing an asymmetry into the propagation path of the laser. This may be in the form of an optical diode structure or a tapered waveguide structure to produce asymmetric cross-coupling of counter-propagating modes of the laser light.

Abstract: A Raman cell for Raman shifting of a laser pump beam, to an output beam of a different wavelength, the cell containing a gaseous Raman medium at a pressure of 100-1000 PSIG. An input window for a pump beam is located at one end of the cell and an output window for a Raman shifted wavelength output beam is located at the cells opposite end. The output window is formed as a plane mirror having an inner face coated with dielectric thin films which provide a high reflectivity for the wavelength of the pump beam and a partial reflectivity at the cell's Raman shifted wavelength. The input window includes at least one lens that forms a converging lens for the pump beam which has a focal length in the Raman medium of about 3/2 of the cell's inner length to substantially focus the pump beam at the center of the cell after it is reflected back by the inner face of the plane mirror.

Abstract: A vertical-cavity surface emitting laser is constructed with an intracavity quantum well photodetector. The quantum well photodetector is placed at an optical intensity peak at the Fabry-Perot wavelength. The device may include a current confinement layer in the form of an oxidation layer, an air gap, or proton implantation. The device may be formed with a semi-insulating substrate, a p+ doped substrate, or an n+ doped substrate. Embodiments of the invention include an air bridge contact, a ridge waveguide structure, and buried heterostructure layers.

Abstract: In a laser cavity having an optical axis, a laser medium for forming a laser beam, the laser medium having a central axis off-set from the optical axis, the laser medium exhibiting focusing characteristics that vary with changes in optical power pumped into the laser medium, at least one pair of mirrors oppositely positioned for reflecting at least a portion of the laser beam, one of the mirrors being an output coupler, the laser cavity further comprising at least one focusing element having a central axis positioned between one of the mirrors and the laser medium such that the central axis of the focusing element is displaced from the optical axis a distance that is a function of the displacement of the laser medium central axis from the optical axis and the optical axis passes through the focusing element to substantially eliminate lensing effects produced by the laser medium.

Abstract: A second harmonic generating apparatus including a semiconductor laser serving as a pumping source, a resonator structure for oscillating a first radiation wave generated by LiSAF (Cr:LiSrAlF.sub.6 : Lithium strontium aluminum fluoride with chromium added) crystal which is a solid-state laser crystal which is excited by the pumping source, a control element for controlling the wavelength of the first oscillation wave, and a nonlinear crystal for performing wavelength conversion into second harmonic which is a second oscillation wave, with the first oscillation wave serving as a fundamental wave, the nonlinear crystal being provided in the resonator. A higher efficiency and reliability of the second harmonic generating apparatus is achieved.

Abstract: A monolithic diode pumped solid-state laser (11) comprising as the laser host neodymium-doped yttrium orthovanadate (Nd:YVO.sub.4) (12, 52) or neodymium-doped gadolinium orthovanadate (Nd:GdVO.sub.4) (57, 67) operating on the .sup.4 F.sub.3/2 .fwdarw..sup.4 I.sub.9/2 (.about.914 nm or .about.912 nm respectively) transition, to which a suitable nonlinear optic material (16), such as potassium niobate (KNbO.sub.3) or beta barium borate (BBO), is bonded. The nonlinear crystal gives rise to intracavity frequency doubling to .about.457 or .about.456 nm. The microlaser is a composite cavity formed from a gain medium crystal and a nonlinear frequency doubling material which together have four spaced parallel dielectrically coated faces (14, 17, 18, 15) and which is positioned in close proximity to a diode laser pump source (13) for phase-matched harmonic generation of blue light along an axis of propagation which lies substantially perpendicular to the two faces of the composite cavity.

Abstract: A laser system with compensated optics contains at least one optical element which is thermally coupled to a heat source in order to thermally compensate for a deformation of optical elements disposed in a beam path of the laser system. The deformation is brought about by the laser beam.

Abstract: Method for making a custom phase-conjugating diffractive mirror for a laser resonator comprising the steps of: (a) choosing a specified beam mode profile a.sub.1 (x,y) that will suit need of said designer, (b) calculating the mode profile b(x',y') which is a value of the specified beam a.sub.1 (x,y) that is propagated to the reflection surface of the diffractive mirror and (c) calculating mirror reflectance t(x',y') which reflects phase conjugate of b(x',y'). A method for fabricating such a mirror is shown. Another aspect of the invention is the addition of a phase adjusting element into a laser resonator, and compensating for the addition of a phase adjusting element in the design of other phase-adjusting elements such as the mirrors.

Abstract: An asymmetric resonant optical cavity is constructed of an optically transmissive dielectric material having an index of refraction n. The cavity is configured as an oval cross-section of area A, having major and minor axes. An optical input couples an optical signal of wavelength .lambda. into the cavity. An output coupler is positioned in a near-field region of a surface point of the cavity, thereby enabling coupling thereinto of optical energy of wavelength .lambda.. The surface point on the cavity is determined by a minimum value of an expression which relates the Sin of the angle of incidence, at an angle .phi., to the curvature of the outer surface of the cavity. Further, the index of refraction n of the cavity's dielectric is chosen so as to avoid emission of physically separated beams at the point of exit of a beam.

Abstract: The ideal source for air-turbulence-corrected distance-measuring interferometry is a single laser that generate overlapping beams at two widely separated wavelengths .lambda..sub.1 and .lambda..sub.2. At least one of the wavelengths, as well as the wavelength ratio, must be known to high degrees of accuracy. Furthermore, at each wavelength, the Iaser should produce a pair of orthogonally polarized frequencies with a frequency splitting that is adjustable over the range of approximately 0.5 MHz to 20 MHz to facilitate AC interferemetric distance measurements with a variety of measurement-mirror velocities.

Abstract: The invention relates to a microlaser cavity having an active laser medium and reflection means at the entrance and exit of the cavity, characterized in that the reflection means are dimensioned in such a way that, in the active medium, the size of a pumping beam is at the most equal to the size of a laser beam emitted by the cavity.

Abstract: An electrostatic precipitator is provided within the housing of a gas discharge laser, such as an exciter laser, to collect and trap dust particles generated in the course of laser operation. The precipitator comprises a plurality of spaced collector plates mounted within the laser housing for flow-through passage of a lasing gas circulated by a fan through a laser discharge zone disposed between a pair of main electrodes. The collector plates are appropriately charged to define one precipitator pole, the opposite pole being defined by the laser discharge zone and the ionization and fluorescent discharge associated therewith during laser operation. The collector plates are shaped and spaced for changing the lasing gas flow direction and for reducing the flow velocity as the lasing gas circulates between the plates, to achieve enhanced electrostatic collection of dust.

Abstract: A method of reducing undulation in the L vs. I curve of a laser which uses a fiber grating is presented. The spectral width of the fiber grating is made larger than the Fabry-Perot spacing of the laser cavity. As a result, as the laser shifts between harmonics due to laser functioning (e.g., laser drive current, laser aging, temperature change, or mechanical stress), the fiber grating is able to respond linearly because of a large spectral width.

Abstract: In a laser device, notably for optical pumping, the wafer includes an expansion segment adjacent the exit to prevent degradation of the exit facet of the semiconductor wafer that constitutes the amplifying part of the laser. The other facet is reflective and a Bragg grating is formed in a coupling fiber disposed near the exit facet. Applications include optical pumping of erbium-doped fiber amplifiers.

Abstract: A polarization independent optical resonator comprising a phase-shifted grating structure is disclosed and analyzed. An application as a polarization independent optical wavelength filter with ultra-narrow bandwidth and fine tunability is described.

Abstract: In an optically stable laser resonator which includes at one end a fully reflective mirror, a partially reflective mirror serving as an uncoupling window at the other end and a pair of spherical optical mirrors one being diverging and the other being converging to provide an expanded beam at the uncoupling window wherein the beam axis has an incidence angle w.sub.1 with the diverging lens axis which is between 10.degree. and 45.degree. and the axis of the beam extending between the spherical mirrors has an incidence angle with the converging mirror axis which, depending on the mirror distance and the focal length of the mirrors, is so calculated that astigmatism is essentially eliminated.

Abstract: A fully integrated photonic IC for optical clock generation using no electronic current modulation. A first and second laser stripes are joined by a Kerr effect non-linear directional coupler, NLDC. The first stripe is pumped with a DC current for laser generation, and the second stripe has a reflector at an end facet for generation of mode selective optical feedback. The DC current generates relaxation oscillation in both stripes and the Kerr effect of the NLDC causes the electric fields in both stripe to interact constructively so as to shift the relaxation oscillation to undamped oscillation. The optical clock generator is tuned by varying the applied DC current.

Abstract: The invention relates to a microlaser cavity, with active Q switching, characterized in that it comprises:an active laser medium (20), an input mirror (22) and an output mirror (24, 87) defining the cavity,a micromodulator with frustrated total internal reflection, comprising two microprisms (32, 34) made of a certain material of index n.sub.1 each having at least one planar face (36, 38), the two planar faces being approximately parallel to each other and inclined on the microlaser cavity axis, thereby defining a plate (30) of a certain material of index n.sub.2 less than n.sub.1.means (44, 46, 48, 50, 52, 54) for varying the thickness of the plate.

Abstract: Low optical loss and simplified fabrication are achieved by a nonlinear reflector which incorporates one or more semiconductor quantum wells within an n half-wavelengths strain relief layer (where n is an odd integer greater than zero) that is formed on a standard semiconductor quarter wave stack reflector. Growth of the half-wavelength layer is controlled so that dislocations are formed in sufficient concentration at the interface region to act effectively as non-radiative recombination sources. After saturation, these recombination sources remove carriers in the quantum well before the next round trip of the optical pulse arrives in the laser cavity. The nonlinear reflector is suitable for laser modelocking at the high wavelengths associated with many currently contemplated telecommunications applications and provides, at such wavelengths, an intensity dependent response that permits it to be used for saturable absorption directly in a main oscillating cavity of a laser.