Abstract: This invention discloses a semiconductor laser incorporating a plurality of resonant optical waveguide array cells. In each of the resonant optical waveguide array cells, leaky waveguide elements are coupled together such that radiation leaked from one antiguide element is coupled with radiation propagating along another antiguide element across an interelement region. As the radiation propagates through the array it is reflected at each end of the array until it builds up enough optical gain to reach lasing threshold. Then, radiation is leaked from the sides of each array such that this radiation can impinge other resonant optical waveguide arrays and be coupled with these arrays in phase to develop a laser beam having a higher intensity than can be achieved with a single array semiconductor laser.

Abstract: A phase lock type semiconductor laser comprising: an array type semiconductor laser main body which includes a plurality of line-shaped active layers having wave guides disposed in parallel with each other, these active layers having waveguide modes optically coupled with each other, and a reflection-type light diffraction element executing a light return or feedback in such a manner that only a specific wavelength beam among emitted beams of coupling modes which are emitted from one end surface of the semiconductor laser main body in terms of a line-shaped light source can be directly focused on the same one end surface of the semiconductor laser main body in a line-shaped.

Abstract: A pulsed laser system capable of operating at higher repetition rates, while maintaining the efficiency and beam quality of the output pulses comprises first and second gain media with one or more pump energy transducers, such as flashlamps, coupled with each of the gain media. A power supply generates a first sequence of pulses of input power and a second sequence of pulses of input power which drive respective subsets of the pump energy transducers in an independent timing relationship. Thus, two non-aligned 50 Hz sequences of input pulses which are interleaved generate an output pulse stream at 100 Hz from the laser system with the efficiency, beam quality, and average power comparable to that of a 50 Hz laser. By pumping subsets of the pump energy transducers coupled to a laser system in an interleaved fashion, higher repetition rates may be achieved with better output beam quality and higher average power than has been obtainable with prior art systems.

Abstract: Multiple discharge gas laser apparatus. A compact apparatus for simultaneously or individually generating a plurality of laser output beams in a selected pattern suitable for marking objects, for communications, or for remote chemical sensing or other remote sensing applications, among other uses, where all of the electrodes providing lasing gas excitation are located in a single gas volume and share a single output coupler is described. In this manner, all of the output beams are parallel in far field, to the extent variations in mode structure permit, without the necessity of undertaking detailed optical adjustments. Moreover, the focal plane of the output laser radiation is insensitive to significant positional variation of focusing optics utilized to increase the intensity thereof for marking purposes. Electrodes can be utilized for more than one discharge; that is, the direction of the discharge can be selected to involve any adjacent electrode having opposite charge polarity.

Abstract: Apparatus is disclosed for generating two streams of optical pulse signals having less than 100 femtoseconds of jitter. A Ti:sapphire laser that is self mode locked by using self focusing in the gain medium and a weak HITCI intercavity dye jet for starting generates a first stream of substantially 100 femtosecond pulses. This first stream of optical pulses is split into two parts, one of which is used as a desired stream of optical pulses and the other of which is used to pump an HITCI dye laser synchronously to generate a second desired stream of optical pulses. The pulses of the second stream from the dye laser have durations of about 140 femtoseconds and less than 100 femtoseconds of jitter relative to the pulses of the first stream.

Abstract: A coupled multiple output ring laser system having a plurality of ring lasers 100,200 that are coupled together, each ring laser having separate output beams 159,280 and separate suppressor mirrors 228,282, is provided with two optical trombones 250,252 mounted on a common phase shifter 268, which changes the optical path length to the suppressor mirror 228 in the laser 100 and changes the optical path length of the mutual coupling path between the laser 100 and the laser 200 in an equal and opposite direction, thereby changing the phase of the output beam 159 of the laser 100 with respect to the output beam of the laser 200, without changing the phase of the output beam 280 from the laser 200. The invention works for any number of lasers and works equally well with reverse-to-forward coupling or forward-to-reverse coupling schemes.

Abstract: A multiple output wavelength laser and technique for generating multiple put laser wavelengths from a solid state lasing material. The solid state material must be able to lase at multiple nonoverlapping transitions such that there are no losses due to gain competition or divided output power.

Abstract: An intensity stabilized laser including a gain cavity containing a gain medium; and an absorbing cavity containing a nonlinear absorbing medium, wherein the absorbing cavity is located with respect to the gain cavity and the characteristics of the nonlinear absorbing medium are selected so as to provide negative feedback from the absorbing cavity to the gain cavity during operation of the laser to thereby control the gain of the gain cavity.

Abstract: A high-power continuous-wave laser resonator (10) is provided, wherein first, second, third, fourth, fifth and sixth mirrors (11-16) form a double-Z optical cavity. A first Ti:Sapphire rod (17) is disposed between the second and third mirrors (12,13) and at the mid-point of the length of the optical cavity, and a second Ti:Sapphire rod (18) is disposed between the fourth and fifth mirrors (14,15) at a quarter-length point in the optical cavity. Each Ti:Sapphire rod (17,18) is pumped by two counter-propagating pump beams from a pair of argon-ion lasers (21-22, 23-24). For narrow band operation, a 3-plate birefringent filter (36) and an etalon (37) are disposed in the optical cavity so that the spectral output of the laser consists of 5 adjacent cavity modes. For increased power, seventy and eighth mirrors (101, 192) are disposed between the first and second mirrors (11, 12) to form a triple-Z optical cavity.

Abstract: In accordance with the present invention, an optical processing device and method are provided for processing with extremely low energy requirements. Spontaneous emissions from an excited optical gain medium generate a waveform that propagates within a cavity defined by the gain medium and a reflective device. A first spatial modulating element is disposed in the cavity in the path of the generated wavefront to impose a first spatial pattern thereon. A second spatial modulating element also is disposed in the cavity and imposes a second spatial pattern on the perturbed wavefront carrying the first pattern. When the first and second imposed spatial patterns have dual spatial pattterns, light is directed back along pathways through the cavity to induce stimulated emission and eventually resonance in the cavity.

Abstract: In the process and by means of the apparatus, several radiation sources (1) arranged in a row, whose emitted radiation intensity distribution is not rotationally symmetrical, are imaged by means of a first, noncentrically imaging functional element (5), then each beam bundle (9) is rotated by means of a beam-rotating element (7), and the beam components of the rotated beam bundles (9) not imaged by the first functional element (5) are imaged by means of a second, noncentrically imaging functional element (11). The functional elements (5, 11) and their locations are chosen so that parallel beam bundles (9) are produced which are focused with a spherical lens (15) into a spatial zone (3). The apparatus according to this invention provides in a simple way a good focusing ability for several individual beams.

Abstract: Separate features of a composite image in a field of view illuminated by a aser beam are respectively monitored by low level optical cavity resonators of an array from which optical data outputs are distributed to high level resonators for optical data correlation. Adjacent low level resonators of the array are coupled by controllers for modal interaction modified by feedback to the controllers from the high level resonators through optical signal transforming means for signal correction purposes in pattern recognition of the composite image.

Abstract: An integrated semiconductor laser device includes electronic direction and focusing control. The integrated semiconductor laser device may be used for either transmitting output laser beams or as a laser amplifier for receiving incoming laser beams. The direction and focusing control of the device operates by applying electric current to electrodes coupled to an active channel within an extension chamber of the integrated semiconductor laser device. The applied currents inject a minority carrier density distribution into the active channel. Since the speed of light within a semiconductor changes with minority carrier density distribution, a laser beam wave front may be shaped by the injected minority carrier density distribution to direct and/or focus a laser light beam. The direction and focusing control is completely integrated within the semiconductor laser device and time constants for the electronic direction and focusing control are in nanoseconds.

Abstract: A semiconductor laser that includes at least one grating reflector with a grating period selected to diffract at a nonperpendicular angle within the plane of the laser waveguide. This allows dispersal of laser light, eliminating filamentary multimode operation of broad area lasers. In one embodiment, the grating reflector couples light between a single transverse mode waveguide portion of the optical cavity and a second, broad area, portion that is not collinear with the single mode waveguide. In another embodiment, the cavity favors a ring mode of oscillation. One or more grating reflectors form part of the feedback mechanism which forms a resonant optical cavity with noncollinear portions. Other reflectors in the feedback mechanism include facet reflectors which can be cleaved or ion milled, or semiconductor material refractive index boundaries. Laser embodiments with two or more grating reflectors can be independently tuned to provide a high rate of amplitude modulation.

Abstract: Slab or stripline gas laser. A slab or stripline gas laser that contains two laser mirrors (4, 5) has a single construction that is extremely mode-stable. The gas laser has a first electrode (1) that carries laser mirrors (4, 5) and that is connected to the laser mirrors (4, 5) in a fixed angular position, and a second electrode (13) that is mechanically fixed relative to the first electrode but is positioned such that it does not contact the laser mirrors (4, 5). The laser structure can be used in CO.sub.2 waveguide lasers.

Abstract: A monolithically integrated multiple-wavelength laser structure includes an array of lasing structures each having a cavity length chosen to correspond to a desired lasing wavelength. The array is suitable for use as a transmitter in a wavelength division multiplexing communication system. The lasing structures preferably include quantum well active regions.

Abstract: A microwave active element is connected in series to a drive circuit of a laser light emitting element and the laser light emitting element is caused to operate as a microwave resonator as viewed from the microwave active element. Laser light from the laser light emitting element is delayed by a delay controller and fed back to the laser light emitting element to control its delay time, thereby controlling the microwave resonance frequency. At the resonance frequency the microwave active element oscillates pulses and provides a microwave signal to its output terminal. The laser light emitting element is driven by a current flowing across the microwave active element and repeatedly emits, at its pulse oscillation frequency, laser light pulses of spectral frequencies which bear higher harmonic relation to the self-oscillation frequency of the microwave active element. By frequency sweeping the resonance frequency of the microwave resonator, the frequency of the laser light can be frequency swept.

Abstract: A semiconductor laser device comprising a semiconductor laser chip emitting infrared laser beams in a predetermined direction and a visible light source emitting visible light beams in the same direction. The semiconductor laser chip and the visible light source are disposed close to each other on a package stem. An optical element is disposed in a direction where both light beams are emitted so as to collimate or converge the visible light beams while allowing the infrared laser beams to pass therethrough without change. By this configuration, the operator can visually locate the infrared laser beams by knowing the location of the visible light beams.

Abstract: A light pulse generator is provided comprising, a first and a second semiconductor laser diodes, each having a highly reflective surface and a non-reflective surface arranged opposite to each other, an optical system arranged between the highly reflective surfaces of the first and the second semiconductor laser diodes with the two non-reflective surfaces being confronted by each other, and a current supply for feeding the first and the second semiconductor laser diodes with discrete high-frequency currents respectively. The high-frequency currents repeat at intervals of a period equal to n times (n being an integer) the duration of light traveling one cycle within the optical resonator and have a phase difference of .pi./n from each other. Accordingly, the light pulse generator can produce a series of short-width light pulses while minimizing the generation of unwanted sub pulses.

Abstract: An electronically tuned, optically pumped, transition metal based, solid-state laser is disclosed. Tuning is achieved by using resonant reflecting means comprising an output mirror, a mirror located between the output mirror and the source of laser light, a polarizer located in the light path between the two mirrors, and an electronically tuned, voltage controlled, variable, liquid crystal waveplate for receiving light passing through the polarizer. The components of the resonant reflecting means are selected to have a longitudinal mode that is anti-resonant with the optical cavity of the laser.

Abstract: A laser diode assembly provides multiple output beams from multiple p-n junctions in a multiplicity of stacked laser diodes with at least one tunnel junction. A semiconductor substrate has a multiplicity of superposed semiconductor laser stacks thereon each having an active layer sandwiched between p and n layers, and at least one pair of adjacent semiconductor laser stacks has a tunnel junction therebetween. When a potential is applied across the ohmic contacts on the outer surface of the substrate and the outer surface of the uppermost semiconductor laser stack, lasing is produced in the semiconductor stacks to form multiple beams. The tunnel junction may be provided by highly doped p.sup.+, n.sup.+ layers between the stacks, or it may be provided by highly doped abutting p.sup.+, n.sup.+ surface portions in the adjacent stacks. Tunnel junctions may be provided at the interfaces between all of the stacks, or between all but one pair of the adjacent stacks.

Abstract: In order to improve a solid-state laser comprising a resonator, at least one solid-state rod arranged in the resonator and a pumping power source for exciting the solid-state rod such that the dissipation heat can be controlled better and excitation for high powers is possible in a simple way, it is proposed that the resonator be a coupled resonator, that the resonator have two elongated excitation sections lying in one plane with one of the solid-state rods being arranged in their respective beam, that the resonator have a coupling section which the beams of the excitation sections enter as outer beams extending parallel to one another but in spaced relation to one another and which couples the excitation sections with one another by displacement of the outer beams in the plane defined by these to a coupling axis lying parallel to and between the outer beams and beyond this coupling axis, and that irradiated by the pumping power source on another side surface.

Abstract: An optical parametric oscillator/laser system includes an optical pump source for generating pump radiation and an embedded dual optical resonator containing an optical parametric oscillator/laser crystal. The embedded dual optical resonator includes a laser resonator and an optical parametric oscillator resonator. The OPOL crystal is an optical parametric oscillator material doped with ions that exhibit lasing transitions. The pump radiation stimulates generation of laser radiation. When the laser radiation reaches the parametric threshold, optical parametric radiation is generated. In one embodiment, the laser resonator and the OPOL resonator are each defined by spaced-apart mirrors. In another embodiment, the OPOL system includes an OPOL rod having end caps at each end. Each end cap includes surfaces for internally reflecting the laser radiation and the parametric optical radiation in a closed loop path so that the OPOL rod and the end caps define an optical resonator.

Abstract: A laser apparatus and method is disclosed comprising a first lasant material which is located in an optical cavity and which produces laser radiation of a first wavelength, and a second lasant material which is pumped by radiation from the first lasant material, which absorbs laser radiation at the first wavelength in an amount generally comparable to the Optimum Output Coupling, which functions as the output coupler for the optical cavity and which lases at a second wavelength. The first lasant material and the second lasant material are preferably selected to have minimal losses such that there is a net gain in the cavity.

Abstract: An optical pulse generating apparatus having a semiconductor laser medium and an external resonator comprising an optical waveguide path. A reflecting element in the optical guide path is given such a reflection wavelength characteristic as to suppress other components than the component of an oscillation main longitudinal mode, so that the level of the main longitudinal mode component is raised and optical pulses with a narrower spectrum width and pulse width are produced.

Abstract: An optically pulsed laser with an unstable resonator configuration is described with two feedback beams. The laser relies on adjoint mode feedback with a single modulator in the low power feedback beam path. The laser is characterized by a two coupled adjoint feedback beams each configured to pass through the modulator in one direction only, thereby doubling the output power potential of the laser.

Abstract: A continuously pumped ring laser is pulsed by modulating a small portion of one of the circulating beams and feeding back the modulated radiation in the adjoint mode.

Abstract: A modelocked laser with an unstable resonator configuration is described. The laser relies on adjoint mode feedback with a modulator in the low power feedback beam path which is not part of the main resonator. The optical cavity length and the path length of the feedback beam are adjusted to provide a pulsed, modelocked output beam.

Abstract: A laser with an unstable resonator configuration is described with a second, lower power auxiliary laser to provide a feedback beam to pulse high power CW lasers without exceeding the power handling capability limitation of currently available modulators. The present laser relies on adjoint mode feedback provided by the auxiliary laser to accomplish pulsed operation with a modulator in the low power feedback beam path. Higher power output beams can be generated with multiple stages of auxiliary laser providing adjoint mode feedback, thereby reducing incident power on modulation devices while providing adequate adjoint beam power to effectively pulse the high power laser. In certain embodiments a single gain generator is used to drive the main and auxiliary lasers.

Abstract: An apparatus comprising a continuous wave (CW) laser and a transverse electrode atmospheric (TEA) pulsed laser, the continuous wave laser and transverse electrode atmospheric pulsed laser each producing laser beams, the laser beams from each of the lasers being provided to an optical mixer for combing the two laser beams into an output beam. The output beam can be either laser beam individually, or a combined coaxial beam wherein the CW laser beam and TEA pulsed laser beam are superimposed on each other. Preferably, the two lasers are CO.sub.2 lasers. The CW laser can also be operated in a pulsed mode. The device is particularly useful for medical and surgical treatment and provides effects not possible before.

Abstract: The invention relates to laser systems of the type comprising optical fiber amplifiers. A laser system comprises a first laser 1 and a second laser 2. The second laser 2 is pumped at a first wavelength .lambda..sub.1 and caused to lase at a second wavelength .lambda..sub.2. The first laser 1 has absorption bands .lambda..sub.1 and .lambda..sub.2. The output .lambda..sub.2 of laser 2 and the remnant pump at .lambda..sub.1 are coupled and both are used to pump the first laser 1, thus causing laser 1 to lase at a third wavelength .lambda..sub.3.

Abstract: An unstable resonator, dc excited, is pulsed using an adjoint coupled beam of low power as the pulsing element. The resonator feedback consists of the self-feedback and the adjoint beam feedback. The self-feedback can be sufficient for self-oscillation and pulsed operation can be achieved by controlling the repetition rate and the magnitude of the adjoint beam power. Complete control and shut-off between pulses with complete freedom of repetition rate is achieved if the self-feedback is insufficient for laser oscillation. The invention was demonstrated on a 10 kilowatt average power CO.sub.2 laser with pulse control provided by with a 100 watt adjoint feedback beam.

Abstract: A laser is fabricated from an optical transmission medium having a laser cavity with an rare earth (e.g. Erbium) doped portion. At least one longitudinal mode is suppressed using a plurality of series coupled Fabry-Perot cavities an optical grating, or a combination thereof. Ring lasers and linear structures are disclosed.

Abstract: A laser 10 is disclosed in which there are incorporated one or more diffractive optical elements (DOE's) 20. The DOE's can be used in place of conventional optics to save costs and allow design of resonators not heretofore possible. The ability to vary the reflectivity of the surface of a DOE in any desired pattern allows unprecedented control of both the intracavity mode as well as the mode of the output beam.

Abstract: Modulation-induced thermal crosstalk between the independently addressable lasers of a monolithic multilaser array is reduced by forming each laser with two optically coupled active regions, an amplifier region and a modulator region, biasing the amplifier region in such a way that stimulated emission is caused to occur therein, and varying the electrical condition of the modulator region in order to modulate the lasers. Modulation of the laser output is achieved by varying the internal optical loss of the modulator region, known as Q-switching. In one form, control of this loss is achieved by varying the reverse bias voltage applied to the modulation region. In another form, control of this loss is achieved by selectively connecting and disconnecting regions of p-type and n-type material in the modulator region together. In a third form, control of this loss is achieved by selectively connecting and disconnecting the modulator region to ground potential.

Abstract: A high power TEM.sub.00 mode Nd:YLF solid state laser includes at least two pumped Nd:YLF solid state rods in series within a laser resonator. A spherical lens may be incorporated within the resonator as required for establishing, in concert with the rods and resonator end mirrors, a large intracavity beam diameter at the position of the rods. A cylindrical lens may be provided to compensate for astigmatic thermal focusing of the Nd:YLF rods, or else the rods may be used in pairs, in which case the rods are rotated by 90.degree. about the laser axis with respect to each other, and a half-wave plate is inserted between the rods of each pair to maintain oscillation at a single wavelength.

Abstract: The disclosure relates to the making of lasers. It is sought to obtain a laser that emits at only one frequency without using frequency selection means (such as filters, etc.) needed in certain types of spectral wideband lasers (vibronic type lasers for example). It is also sought to make the laser tunable by simple means. To achieve these goals, it is proposed to define a laser cavity in which one of the mirrors is not a standard mirror but a mirror with an active function in the sense that it does not merely reflect light but itself produces light at only one wavelength. The active mirror is preferably a Bragg reflector made with an alternation of layers, at least one of which is a semiconductor layer. This layer collects electron-hole pairs in response to the excitation by the fluorescence photons. It re-emits photons at a wavelength determined by the forbidden band width of the semiconductor.

Abstract: The invention relates to the design of multiwavelength LED devices having multiple-lobe optical spectrums and laser diode devices with multiple designated wavelengths wherein the devices are formed by stacking various active layers of selected semiconductor materials whereby each layer is assigned to be active at a different wavelength. The independent layers are active at different wavelengths based on both their material composition and Quantum Well geometry. Independent control of current to each layer is allowed which in effect controls the spectral intensity distribution and the spectral widths. The step of allowing independent control of the current is achieved by considering the probabilities of carrier capturing, recombining carriers at various active layers and minimizing the current through all the barriers and cladding layers and optimizing the current through each active layer by controlling the individual thicknesses.

Abstract: An apparatus for generating a relatively high-power, modulated optical beam s disclosed. The apparatus comprises a first element for emitting a relatively low-power laser beam at a preselected wavelength, means for focusing the laser beam into a focused beam, a damage-resistant integrated optic modulator responsive to the focused beam for developing a modulated beam, optical means for shaping the modulated beam into a shaped modulated beam, and semiconductor means having a large active area responsive to the shaped, modulated beam for producing a relatively high-power, output modulated beam. In a first embodiment, the semiconductor means is a semiconductor amplifier which amplifies the modulated beam to produce the high-power, modulated output beam.

Abstract: A Q-switched laser having a gain medium disposed within a first cavity and a second cavity whose optical path length is adjustable such that the quality of the first resonant cavity is affected. One aspect of the invention is the changing of the physical path length of the second cavity so as to affect the reflectivity of a mirror common to both cavities as seen from the first cavity. Another aspect of the invention is the incorporation, within the second cavity, of a material whose refractive index or absorption coefficient can be varied by the application of an electric field, a magnetic field, a temperature change or an applied pressure.

Abstract: A semiconductor light emitter comprising a substrate of a semiconductor material having a pair of opposed surfaces and a body of semiconductor material on one of the surfaces. The body includes a pair of clad layers of opposite conductivity types having an intermediate quantum well region therebetween. The clad layers are of a semiconductor material which forms a heterojunction with the material of the quantum well region. The clad layers and the quantum well region form a waveguide which extends along the body. A plurality of gain sections are formed in the body spaced along and optically coupled by the waveguide. Each of the gain sections is adapted to generate light therein when a voltage is placed thereacross. One of the gain section has gratings at each end thereof which are adapted to reflect light back into the one gain section and thereby create a beam of light.

Abstract: The invention concerns a device for generating light, in particular light for use in length measurement using an interferometer. The frequency of the laser light emitted is controlled as a function of the wavelength in the surrounding gaseous medium (air) in such a way that the wavelength in the air remains constant. The light source in this device is a laser diode. Located external to the laser resonator is a device for feeding back to the resonator, at selected frequencies, light emitted by the laser diode.

Abstract: Device able to continuously tune a coherent and rectilinearly polarized light source. It includes an electro-optical device (5) forming a spectral filter with an electrically modulable transfer function, this electro-optical device being provided so as to select a particular longitudinal mode from all the longitudinal modes able to oscillate inside the external cavity for which the source (1) is provided and which is ended by a reflecting device (3) towards the source of the light emitted by this source, and an electro-optical device (4) for varying the optical length of the cavity, this variation device being placed in the cavity and provided so as to continuously move the position of the selected longitudinal mode, each electro-optical device including a compact electro-optical crystal.

Abstract: Device for coherent addition of laser beams including several optical amplifiers in parallel pumped by a beam coming from a master laser. The beams emitted by these amplifiers are transmitted to a non-linear material and play the role of pump beams. The non-linear material also receives a signal beam derived from the master laser. The various beams of the amplifiers are therefore added in the non-linear material along the direction of the signal beam.

Abstract: In a solid-state laser device comprising a laser medium which is located within a plurality of resonance optical paths and which has a plurality of medium lengths forming parts of the resonance optical paths, at least one of the medium lengths within the resonance optical paths is selected such that a third level laser beam can be oscillated while at least one of the remaining medium lengths is different from the first of the medium lengths and is selected such that a fourth level laser beam is oscillated.

Abstract: A carrying structure for the flanges and other elements of two laser beam paths has a geometric central plane zone that lies between and parallel to geometric central plane zones of the two laser beam paths so that the carrying structure includes the flanges of the first and second laser beam paths, is common to at least two laser segments, and that the first central plane zone of the first laser segment is disposed parallel to the second central plane zone of the second laser segment.

Abstract: A switchable multichannel external cavity injection laser incorporates a diffraction grating between a linear array of n reflectors and a common reflector to define a set of n optical cavities having different frequency bands. Each of the (n+1) reflectors is provided by the optically distal end of an associated semiconductor laser amplifier whose optically proximal end is arranged to be substantially non-reflective.

Abstract: Part of a laser beam, which is generated by a laser tube and reflected by a reflection surface of a high-reflectance mirror to travel while diverging at the predetermined angle, is divided by a dividing mirror. The spectral band width of the divided laser beam is narrowed by an etalon and a diffraction grating. The laser beam with the narrowed spectral band width is reflected by a high-reflectance return mirror, returned to the laser tube, and amplified in the laser tube. The laser beam with the narrowed spectral band width is amplified in substantially the same space within the laser tube where the laser beam was generated.

Abstract: A semiconductor laser which includes a controllable beam splitter has three segments including laser-active zones and a monitor diode forming a cross-shaped laser connected with one another by way of the beam splitter. The beam splitter is equipped with electrodes for controlling optical coupling between the segments.

Abstract: A semiconductor laser array includes a plurality of stripe-shaped stimulated regions of the index guide type. A plurality of buried layers are disposed between each of the plurality of stripe-shaped stimulated regions. A light absorption layer is formed in each of the plurality of stripe-shaped stimulated regions so that the stimulated region has the optical loss greater than an buried layer, whereby optical coupling is performed with no phase difference.