Abstract: Systems and method for manipulating optical pulses to implement an optical switch and for pulse shaping (e.g., pulse compression and/or compression) are disclosed. In one embodiment, the system comprises an optical switch apparatus that includes a plurality of resonators optically coupled to a waveguide, two output waveguides, an input light source, a control light source. The system selects some of the input signals emitted from the input light course using control signals emitted from the control light source to route to one of the output waveguides. In another embodiment, the system includes a waveguide optically coupled to a plurality of resonators, input light source, optional resonator modules that can change the refractive index of the resonators, and an optional amplifier. This system can change the shape of the pulses by changing a number of parameters, such as the incoming pulse amplitude and/or the refractive index of the resonators.

Abstract: A laser apparatus capable of emitting laser beams of a plurality of different wavelengths includes: a solid-state laser medium which emits light of a plurality of different peak wavelengths; a resonance optical system which resonates the emitted light of the plurality of different peak wavelengths and converts respective light to oscillate the laser beams of the plurality of different wavelengths; and a ¼ wave plate for a wide band, which is placed in the resonance optical system and has a property of providing a uniform phase difference to the light of the plurality of different peak wavelengths to be converted.

Abstract: The invention is in the field of distributed Raman amplification for digital and analog transmission applications and other applications, e.g., instrumentation and imaging applications, including HFC-CATV applications. In particular, the invention uses a high power broadband source of amplified spontaneous emission (ASE) as the Raman pump source for improved system performance. The invention also includes methods for constructing such a high-power broadband Raman pump.

Abstract: A conductive element with a lateral oxidation barrier is provided for the control of lateral oxidation processes in semiconductor devices such as lasers, vertical cavity surface emitting lasers and light emitting diodes. The oxidation barrier is formed through modification of one or more layers which initially were receptive to oxidation. The quality of material directly below the oxidation barrier may be preserved. Related applications include the formation of vertical cavity surface emitting lasers on non-GaAs substrates and on GaAs substrates.

Abstract: An optically pumped radiation-emitting semiconductor device with a surface-emitting quantum well structure (10), which has at least one quantum layer (11), and an active layer (8) for generating pump radiation (9) for optically pumping the quantum well structure (10), which is arranged parallel to the quantum layer (11). The semiconductor device has at least one emission region (12), in which the quantum well structure (10) is optically pumped, and at least one pump region (13). The quantum well structure (10) and the active pump layer (8) extend over the pump region (13) and over the emission region (12) of the semiconductor device, and the pump radiation (9) is coupled into the emission region (12) in the lateral direction.

Abstract: A solid-state laser device, comprising two or more resonators for outputting laser beams on a same axis, a first light emitter and a second light emitter for entering excitation light to each of the resonators, a photodetector for monitoring which monitors the outputted laser beams, and a control unit for performing constant output control of at least one of the first light emitter and the second light emitter based on a signal from the photodetector for monitoring.

Abstract: A semiconductor laser apparatus capable of reducing a spread angle of emission light with downsizing has an active region between first and second end surfaces. A first reflection structure and a partial reflection structure are provided on the first end surface side. The end surface of the active region is divided into a total reflection region and a partial reflection region in combination with the first reflection structure and partial reflection structure. A laser resonator includes the first reflection structure and partial reflection structure. A second reflection structure is positioned on the way of a resonance optical path of the laser resonator. Light emitted within the active region propagates on a resonance optical path. An induction emission is produced. The semiconductor laser carries out a laser oscillation. Of the light arriving at the partial reflection structure, the portion transmitted through the partial reflection structure is outputted outside the apparatus.

Abstract: The invention is in the field of distributed Raman amplification for digital and analog transmission applications and other applications, e.g., instrumentation and imaging applications, including HFC-CATV applications. In particular, the invention uses a high power broadband source of amplified spontaneous emission (ASE) as the Raman pump source for improved system performance. The invention also includes methods for constructing such a high-power broadband Raman pump.

Abstract: A method of establishing the properties of a three-mirror laser, where the properties are the three mirror reflectivities and the two cavity lengths (i.e., the separations between the mirrors). Initially, a conventional two-mirror laser is designed, providing values for a laser cavity length and for power reflectivities of a high reflectance mirror and an effective mirror. Then, the effective mirror is replaced by a pair of mirrors with a separation equal to an external cavity length, and reflectivities that may be varied in tandem so that when the reflections from the pair of mirrors are in phase, the combined power reflectivity of the pair of mirrors is equal to that of the effective mirror. A quantity ? is defined to measure the relative shift in power reflectivity between the pair of mirrors. ? is varied over all its possible values, and various criteria are evaluated with respect to ?.

Abstract: A vertically-coupled whispering gallery mode (WGM) resonator optical waveguide, a method of reducing a group velocity of light, and a method of making a waveguide are provided. The vertically-coupled WGM waveguide comprises a cylindrical rod portion having a round cross-section and an outer surface. First and second ring-shaped resonators are formed on the outer surface of the cylindrical rod portion and are spaced from each other along a longitudinal direction of the cylindrical rod. The first and second ring-shaped resonators are capable of being coupled to each other by way an evanescent field formed in an interior of the cylindrical rod portion.

Abstract: Wafer-level stage testing of semiconductor lasers can be facilitated by directing a light beam emitted from the semiconductor laser toward a direction different from a path of the light beam as originally emitted from the laser. A test structure can be coupled to a back facet of the laser and can include a first region separated from a second region by an inclined interface. When a light beam is emitted from the laser, the light beam can be received on the inclined interface and then directed toward a light detector for detection and evaluation.

Abstract: A system for generating a powerful laser beam includes a first laser element and at least one additional laser element having a rear laser mirror, an output mirror that is 100% reflective at normal incidence and <5% reflective at an input beam angle, and laser material between the rear laser mirror and the output mirror. The system includes an injector, a reference laser beam source, an amplifier and phase conjugater, and a combiner.

Abstract: A surface emitting semiconductor laser system having four cavities that couple light from a single aperture. Each of the four cavities overlaps at the outcoupling aperture. Each cavity is fabricated to resonate at a different central wavelength, outputting a different frequency of light, each of which can be independently modulated.

Abstract: An apparatus for and a method of amplifying Faraday or Voigt rotation by passing light through a sample many times using multiple internal reflections and successive mirrored chambers that repeatedly send the light back through the sample. The sample is placed in a sample chamber that is adjacent to an optical amplifier chamber, and the optical amplifier chamber is adjacent to one or more additional chambers. The sample has a magnetic field applied thereto. The sample chamber receives light from a light source. The light reflects within the sample chamber and the sample to accumulate rotation of the light. The sample chamber transmits the light to the optical amplifier chamber. The optical amplifier chamber transmits the light to the additional chambers and reflects the light back to the sample where the light undergoes further rotation. Each one of the additional chambers transmits the light to the next additional chamber and reflects the light back to a previous chamber.

Abstract: An optical bandwidth source for generating amplified spontaneous emission (ASE) across a selected wavelength range, the optical bandwidth source including a waveguide having a first end and a second end, and comprising a plurality of separate wavelength gain subsections arranged in a serial configuration between the first end and the second end so as to collectively form an active waveguide between the first end and the second end; wherein each of the wavelength gain subsections is configured to produce ASE across a wavelength range which is less than, but contained within, the selected wavelength range, whereby the plurality of separate wavelength gain subsections collectively produce ASE across the selected wavelength range.

Abstract: The invention is directed to optical devices comprising a solid-state structured glass substrate having at least one waveguide incorporated therein, particularly waveguides and lasers incorporating such structure. The invention is also directed to methods for modifying such devices and their properties. The waveguides and lasers of the invention provide advantageous high power and increased slope efficiency and find use, for example, in telecommunications applications.

Abstract: A fiber laser with a fiber for laser light generation having an entrance end and an exit end comprises a pump light source for generating pump light to be coupled via the entrance side into the fiber. At the exit end of the fiber a first resonator mirror is provided which is highly reflecting for the laser light to be generated in the wavelength range with the smallest light amplification and to the light of the pump light source. Spaced from the first resonator mirror a second resonator mirror is provided via which light of further wavelength ranges can be fed back into the fiber with the aid of a collimating lens.

Abstract: A photonic crystal-based resonant cavity includes a first dielectric substance having a first dielectric permittivity, a plurality of second dielectric substances having a second dielectric permittivity and arranged in a first periodic structure with respect to at least one or more directions on a plane formed of the first dielectric substance, a plurality of third dielectric substances having a third dielectric permittivity and arranged in a second periodic structure with respect to at least one or more directions on the plane formed of the first dielectric substance, and disposed in unit cells formed by the plurality of second dielectric substances so as to be arranged in a third periodic structure together with the plurality of second dielectric substances, and one or more local defects formed to disrupt either the first periodic structure formed by the second dielectric substances or the second periodic structure formed by the third dielectric substances.

Abstract: Two parallel sets of groups of beams from diode laser bars are spaced apart by a distance V. The two sets of beam groups are interleaved by a beam combiner to provide on set of beam groups spaced apart by a distance V/2. The beam combiner includes a plurality of reflective strips in a plane inclined to the direction of propagation of the beam groups. One set of beam groups is transmitted through the beam combiner without being intercepted by the reflective strips. The other set of beam groups is interleaved with the transmitted set of beam groups by reflecting the other set of beam groups from the reflective strips.

Abstract: The present invention contemplates a simplified laser oscillator-amplifier system for deep UV generation. The simplified system employs same type of gain media in both the oscillator and the amplifier and utilizes a single pump pulse split to pump both the oscillator and the amplifier. A short cavity oscillator is operated near lasing threshold to produce a seed pulse with a narrow spectral bandwidth and long pulse duration. A short cavity amplifier is Q-switched to amplify the seed pulse to produce a single short pulse with good energy extraction efficiency. The amplifier is simply a short cavity, Q-switched laser. Short pulse is obtained with short cavity length and high gain of the amplifier. Consequently, the simplified laser oscillator-amplifier system can accommodate a long pump pulse to produce a nanosecond pulse suitable for deep UV laser generation.

Abstract: A multi-beam semiconductor laser device capable of emitting respective laser beams with uniform optical output levels and enabling easy alignment is provided. This multi-beam semiconductor laser device (40) is a GaN base multi-beam semiconductor laser device provided with four laser stripes (42A, 42B, 42C and 42D) which are capable of emitting laser beams with the same wavelength. The respective laser oscillating regions (42A to 42D) are provided with a p-type common electrode (48) on a mesa structure (46) which is formed on a sapphire substrate (44), and have active regions (50A, 50B, 50C and 50D) respectively. Two n-type electrodes (52A and 52B) are provided on an n-type GaN contact layer (54) and located as common electrodes opposite to the p-type common electrode (48) on both sides of the mesa structure (46). The distance A between the laser stripe (42A) and the laser stripe (42D) is no larger than 100 ?m.

Abstract: A laser system includes a resonator having two gain modules generating pulses, coupled with intra-cavity polarization into a single beam line, using a single output coupler. A laser controller controls the laser heads to emit pulses in rapid succession, such as pulse pairs separated by a time interval of less than about 1 millisecond, and in some embodiments in a range from about zero (overlapping) to about 100 microseconds. Also a system adapted for metrology using particle image velocimetry PIV uses the resonator. For PIV, optics are provided in the output beam paths which expand the beam to form pulsed illumination sheets. A camera is used to capture images of the pulsed illumination sheets for analysis.

Abstract: A tunable semiconductor laser device is presented. The device comprises a laser structure formed by at least two waveguides and an active region located within at least a segment of one of the waveguides; and comprises a tunable spectral filter optically coupled to the laser structure. The tunable spectral filter includes at least two filtering elements, at least one of them being a microring cavity.

Abstract: Apparatus for frequency conversion of light, the apparatus comprises: a light-emitting device for emitting a light having a first frequency, the light-emitting device being an edge-emitting semiconductor light-emitting diode having an extended waveguide selected such that a fundamental transverse mode of the extended waveguide is characterized by a low beam divergence. The apparatus further comprises a light-reflector, constructed and designed so that the light passes a plurality of times through an external cavity, defined between the light-emitting device and the light-reflector, and provides a feedback for generating a laser light having the first frequency. The apparatus further comprises a non-linear optical crystal positioned in the external cavity and selected so that when the laser light having the first frequency passes a plurality of times through the non-linear optical crystal, the first frequency is converted to a second frequency being different from the first frequency.

Abstract: A circuit module including at least one Application Specific Integrated Circuit (ASIC) and a plurality of Vertical Cavity Surface-Emitting Laser (VCSEL) array modules is built using a standard ceramic or organic Multi-Chip Module (MCM) package substrate, resulting is a high density device with a small footprint. Interconnection between the electronic devices and the VCSEL array modules is accomplished using standard integrated circuit packaging technology and flexible connectors. Optical connections from the VCSEL arrays to fiber optic cables are made possible by integrating industry-standard optical connectors onto the package. Optical receiver and transceiver modules may also be incorporated into the circuit module.

Abstract: The present invention relating to a device and method for multiplication of repetition frequency in optical pulse trains. The device and the method multiply repetition frequency of optical pulse train generated with ML-FRL with high stability. The device comprises an optical fiber ring composed of optical fibers, an optical amplifier and a modulator for optically modulating, and an electric signal generator generating high frequency signals. The device generates an optical pulse train of repeating frequency of fm, when applying electric signals of frequency of fm to the modulator. In addition to the construction, the stabilized optical pulse generator comprises a filter passing through frequencies of integer multiple of the applied modulation frequency fm, and a composite cavity composed of a plurality of optical fibers of which lengths are different each other.

Abstract: An active gain region sandwiched between a 100% reflective bottom Bragg mirror and an intermediate partially reflecting Bragg mirror is formed on a lower surface of a supporting substrate, to thereby provide the first (“active”) resonator cavity of a high power coupled cavity surface emitting laser device. The bottom mirror is preferably in direct thermal contact with an external heat sink for maximum heat removal effectiveness. The reflectivity of the intermediate mirror is kept low enough so that laser oscillation within the active gain region will not occur. The substrate is entirely outside the active cavity but is contained within a second (“passive”) resonator cavity defined by the intermediate mirror and a partially reflecting output mirror, where it is subjected to only a fraction of the light intensity that is circulating in the gain region.

Abstract: An inherently efficient direct eye-safe laser based on Er:Crystal technology utilizing intra-cavity energy conversion. The Er:Crystal laser is intra-cavity pumped by a highly efficient ytterbium or neodymium crystal laser, which is in-turn, pumped by conventional infrared diodes array bars. The laser is inherently compact and low-cost allowing for significant scaling of the output energy and power with greatly reduced number of required diode pump sources. This intra-cavity pump scheme of appropriate Er:Crystals also provides for efficient generation of ultra-short Q-switched pulse operation of such lasers.

Abstract: A vertical cavity surface emitting laser having an InP substrate and a lower mirror stack comprised of a plurality of alternating layers of AlPSb and GaPSb over the InP substrate. An InP spacer is over the lower mirror stack. An active region is over the InP spacer, and a tunnel junction is over the active region. Then a top mirror structure comprised of a low-temperature formed first GaAs buffer layer, a high-temperature formed second GaAs seed layer, an insulating structure having an opening, and a GaAs/Al(Ga)As mirror stack that is grown by lateral epitaxial overgrowth.

Abstract: In a device to generate laser light, with a laser-active main resonator (2) and a coupled non-linear resonator (6), each of the two resonators (2, 6) being delimited by mirrors (8, 4; 4, 10), and one mirror (4) of the main resonator (2) being identical to a mirror (4) of the coupled non-linear resonator (6), it is provided that the non-linear resonator (6) is designed for a power loss less than 63% of the power which is coupled via the main resonator (2) and the mirror which delimits the coupled non-linear resonator (6), and the laser-active main resonator is designed so that in laser operation it has a threshold pump power which is less than one fifth, preferably less than one tenth, of the pump power which is used and using which this resonator is excited.

Abstract: A semiconductor laser element includes: a semiconductor laser region in which at least one laser emission portion including an active layer for emitting light is provided; a multimode interference region including a first wave-guiding layer, one end of the first wave-guiding layer being optically coupled to the active layer of the at least one laser emission portion; and an output waveguide region including a second wave-guiding layer, the second wave-guiding layer being optically coupled to another end of the first wave-guiding layer, wherein the active layer of the at least one laser emission portion, the first wave-guiding layer, and the second wave-guiding layer are integrally formed.

Abstract: An apparatus for the generation of variable duration laser pulses comprising an optical cavity delimited by two mirrors, one of which is a total reflection mirror and the other a partial reflection mirror, and containing an active medium with an appropriate excitation system. An optical shutter capable of inducing a Q-switching mode is provided between the total reflection mirror and the active medium. The active medium is optically connected with said total reflection mirror by optical fibre sections having different lengths and may be interchanged in the optical path so as to vary the duration of the pulses emitted by the laser when it operates in the Q-switching mode.

Abstract: A laser system is constructed so that a solid-state laser beam emitted from an Nd:YAG laser unit and a laser diode beam emitted from a combining LD which oscillates in a wavelength range shorter than that of the solid-state laser beam are combined by a dichroic beam splitter, the resultant beam is guided to an optical fiber, and a workpiece is irradiated with the combining LD beam and the solid-state laser beam with absolute irradiation positions and irradiation shapes of the beams almost matched each other. Thus, problems of high cost and high power consumption of the laser system due to low energy conversion efficiency, which become problems in a high-output high-luminance solid-state laser unit can be solved.

Abstract: Two parallel sets of groups of beams from diode laser bars are spaced apart by a distance V. The two sets of beam groups are interleaved by a beam combiner to provide on set of beam groups spaced apart by a distance V/2. The beam combiner includes a plurality of reflective strips in a plane inclined to the direction of propagation of the beam groups. One set of beam groups is transmitted through the beam combiner without being intercepted by the reflective strips. The other set of beam groups is interleaved with the transmitted set of beam groups by reflecting the other set of beam groups from the reflective strips.

Abstract: A semiconductor laser (100) comprises, in succession, a first reflector (102), a first optically active region (104), which can emit light of a first wavelength (&lgr;1), a second reflector (107), a second optically active region (110), which can emit light of a second wavelength (&lgr;2), which is shorter than the first wavelength (&lgr;1), and a third reflector (112), wherein the two optically active regions (110, 112) are able to emit their light on a common optical axis (118) in a common emission direction (119).

Abstract: In a device and method for generating laser radiation based on semiconductors, with which laser light of a high beam quality can be produced, the device producing laser radiation has a reflective element, which has no influence on the divergence of the light exiting the semiconductor and is placed at a distance from the semiconductor at which the arrangement forms an external unstable resonator, the divergent light exiting the semiconductor.

Abstract: A solid-state laser device, comprising a first resonator arranged on a first optical axis, a second resonator arranged on a second optical axis, a first light emitter for entering an excitation light to the first resonator, a second light emitter for entering an excitation light to the second resonator, and further comprising a separated optical axis portion serving as a part of the first optical axis, a separated optical axis portion serving as a part of the second optical axis, a common optical axis portion where the first optical axis and the second optical axis are superimposed, a first solid-state laser medium arranged on the separated optical axis portion of the first optical axis, a second solid-state laser medium arranged on the separated optical portion of the second optical axis, and an optical member for wavelength conversion and wavelength switching means arranged on the common optical axis portion, wherein the optical member for wavelength conversion comprises a plurality of optical crystals for

Abstract: A solid-state laser device, comprising a first resonator arranged on a first optical axis, a second resonator arranged on a second optical axis, a first light emitter for entering an excitation light to the first resonator, a second light emitter for entering an excitation light to the second resonator, a common optical axis portion commonly used by the first optical axis and the second optical axis, a wavelength separating plate for separating the first optical axis from the second optical axis so that the common optical axis portion can be commonly used by the optical axes, an output portion provided on the common optical axis portion, a first solid-state laser medium arranged on a separated optical axis of the first optical axis, a second solid-state laser medium arranged on a separated optical axis of the second optical axis, and an optical crystal for wavelength conversion arranged on the common optical axis portion.

Abstract: A vertical cavity surface emitting laser (VCSEL) using photonic crystals with a central defect. At least one of the mirror layers of a VCSEL includes a photonic crystal with a central defect. The central defect, which is surrounded by a periodic structure of holes or cavities, permits laser light to propagate and exit the VCSEL. Semi-insulating regions are formed in the active region such that when cavities are drilled in the photonic crystal and penetrate the active region, the cavities pass through the semi-insulating regions. This reduces the surface recombination that would otherwise occur in the active region and prevents the threshold current from increasing. The photonic crystal with a central defect has a reflectivity that is wavelength dependent. The VCSEL thus emits a single mode.

Abstract: Stable single mode operation of an external cavity semiconductor laser is obtained by a laser control method that monitors at least one optical beam which is generated by reflection from a wavelength selective element within the laser cavity. The method of the present invention provides stable single mode operation and significantly decreases the mode hop rate, because the signal obtained by reflection from a wavelength selective element within the laser cavity provides a clear indication of an impending mode hop.

Abstract: A vertically emitting semiconductor laser with an external resonator, a semiconductor body (1) in which a quantum well structure (4) is located as active zone that includes quantum wells (6) and barrier layers (5) situated therebetween, and at least one pumping radiation source (9) for irradiating into the active zone at an incidence angle &agr;p pumping radiation (10) of wavelength &lgr;p. The wavelength &lgr;p and the incidence angle &agr;p of the pumping radiation are selected in such a way that the absorption of the pumping radiation takes place substantially inside the quantum wells. This avoids the losses during the capture of charge carriers from the barrier layers into the quantum wells that occur in the case of optically pumped semiconductor lasers where the pumping radiation is absorbed in the barrier layers.

Abstract: A laser device for generating laser pulses with an optically pumped semiconductor laser (1), which has an external resonator and at least one mode-locker (10).

Abstract: An optical pulse train generator is composed of first and second optical resonators and an optical pulse generator. The first optical resonator has therein a first optical path of a first optical path length. The second optical resonator is inserted into the first optical path. The second optical resonator has therein a second optical path of a second optical path length substantially equal to 1/m of the second optical path length, m being a natural number. The optical pulse generator provides the first optical resonator with a first optical pulse train including a component of a first repetition rate tuned corresponding to the first optical path length. The provision of the first optical pulses allows a second optical pulse isolator to be generated in the first optical resonator. The first optical resonator extracts a portion of the second optical pulse train to output an output optical pulse train.

Abstract: The present invention contemplates an integrated oscillator-amplifier system for deep UV generation. The system employs a long cavity oscillator to lengthen the pulse build-up time and to control the pulse spectral bandwidth. Meanwhile the system employs a short cavity amplifier to shorten the energy extraction time to produce a single short pulse with good energy extraction efficiency. The system further integrates the oscillator and the amplifier by inserting the amplifier cavity inside the oscillator cavity via a mirror of low reflectivity. As a result, the integrated system has a long build-up time to generate a seed pulse in the long cavity oscillator and has a short energy extraction time to generate a short amplified single pulse in the short cavity. Consequently, the integrated system can accommodate a relatively long pump pulse to produce a single short amplified pulse suitable for deep UV laser generation.

Abstract: A unit cell is disclosed that facilitates the creation of a layout of at least a portion of a microelectromechanical system. The unit cell includes a plurality of electrical traces. Some of these electrical traces pass through the unit cell. Other electrical traces extend only part way through the unit cell. At least certain boundary conditions exist for the unit cell that allow the same to be tiled in a row and in a manner that results in adjacently disposed unit cells in the row being electrically interconnected in the desired manner.

Abstract: A laser indicator has a laser mechanism having three laser generators generating laser beams perpendicular to each other. Each of the three laser generators is electrically coupled to a separate laser control motor for independent control of the beam of the corresponding laser generator. The laser indicator further includes an adjusting mechanism including a control circuit module, a frame having an adjustment support associated therewith, and a plurality of level control motors disposed in the frame. The laser indicator also includes a laser generator adjuster and tightener.

Abstract: The invention relates to the stabilization of high power semiconductor laser diode sources as they are extensively used in the field of optical communication. Such lasers are mostly employed as so-called pump laser sources for fiber amplifiers, e.g. erbium-doped fiber amplifiers, and are designed to provide a narrow-bandwidth optical radiation with a stable power output in a given frequency band. To improve the wavelength locking range of such laser sources when operating without an active temperature stabilizing element, an external reflector providing very high relative feedback is used. The reflectivity bandwidth of the external reflector is broadened for improving the stability of the laser source. In commonly employed optical fibers for conducting the laser beam, the external reflector is formed by one or a plurality of appropriately designed fiber Bragg gratings.

Abstract: Known laser diode selections are limited to those designed for high power applications (high gain) or those designed for stable single mode operation in an external cavity (low gain). Exponential gain of laser diodes implemented according to embodiments of the present invention is improved (i.e., optimized) to provide both high output power and stability in an external cavity. This is accomplished by controlling the number of quantum wells, light confinement factor, and the transparency current of the laser diode.

Abstract: An optical fiber transmitter for emitting an information-carrying laser beam comprises an optically or electrically pumped single mode MQW (multi-quantum well) semiconductor amplifying mirror as a gain medium and a separate external reflector to form a cavity. The external cavity length defines a comb of optical modes, all or a subset of which correspond to channel wavelengths of an optical telecommunications system having plural optical channels. The semiconductor gain element has a homogeneously broadened gain region; a tuning arrangement tunes the laser from mode to mode across the gain region, thereby selecting each one of the plural optical channels. When the maximum gain bandwidth is less than mode-to-mode spacing defined by the cavity, the tuning arrangement includes a means of altering the temperature of the amplifying mirror, thereby translating the frequency of the gain peak from one mode to another.

Abstract: Adjustment of a tunable external-cavity laser is simplified by incorporating a mount that includes a base, a main body, a reflecting surface, a diffracting surface and a hinge coupling the main body to the base. The laser additionally includes a light source, a converging lens located to receive light from the light source, a tuning mirror and a pivoting arm on which the tuning mirror is mounted. The main body is bounded in part by two plane, external surfaces orthogonal to a common reference plane and angularly separated from one another by an angle. The reflecting surface has a spatial orientation defined by one of the external surfaces and is arranged to receive light from the lens. The diffracting surface has a spatial orientation defined by the other of the external surfaces, and diffracts light received from the reflecting surface towards the tuning mirror. The hinge is located opposite the angle and parallel to the reference plane.