Abstract: Systems and methods are disclosed that provide a direct indication of the presence and concentration of an analyte within the external cavity of a laser device that employ the compliance voltage across the laser device. The systems can provide stabilization of the laser wavelength. The systems and methods can obviate the need for an external optical detector, an external gas cell, or other sensing region and reduce the complexity and size of the sensing configuration.

Abstract: A diode laser and a laser resonator for a diode laser are provided, which has high lateral beam quality at high power output, requires little adjustment effort and is inexpensive to produce. The laser resonator according to the invention comprises a gain section (GS), a first planar Bragg reflector (DBR1) and a second planar Bragg reflector (DBR2), wherein the gain section (GS) has a trapezoidal design and the first planar Bragg reflector (DBR1) is arranged on a first base side of the trapezoidal gain section (GS) and the second planar Bragg reflector (DBR2) is arranged on the opposing base side of the trapezoidal gain section (GS), wherein the width (D1) of the first planar Bragg reflector (DBR1) differs from the width (D2) of the second planar Bragg reflector (DBR2).

Abstract: A master oscillator system may include a grating configured to function as one resonator mirror in an optical resonator, a spectral bandwidth tuning unit configured to tune the spectral bandwidth of a laser beam transmitted within the optical resonator, a storage unit configured to store a control value of the spectral bandwidth tuning unit corresponding to a desired spectral bandwidth and a controller configured to control the spectral bandwidth tuning unit based on the control value stored in the storage unit.

Abstract: A component having a microring resonator and grating, coupled to a waveguide is described. By selection of the grating period, and other parameters such as the grating-waveguide coupling coefficient, an efficient filter may be designed and constructed. The component may be used in passive devices such as add-drop multiplexers or sensors, or in active devices such as lasers. Designs having essentially no response sidelobes, very narrow effective bandwidths, and fast filter roll-offs may permit compact devices to be produced, when compared with typical distributed sampled Bragg grating structures.

Abstract: A laser apparatus uses a dysprosium doped chalcogenide glass fiber. The glass fiber has a laser pump operatively connected to it. The chalcogenide glass fiber is located in a laser cavity including one or more reflective elements such as a Bragg grating, a Bragg minor, a grating, and a non-doped fiber end face. The apparatus provides laser light output at a wavelength of about 4.3 ?m to about 5.0 ?m at a useful power level using laser light input at a wavelength of from about 1.7 ?m to about 1.8 ?m. Also disclosed is a method for providing laser light output at a wavelength of about 4.3 ?m to about 5.0 ?m using the apparatus of the invention.

Abstract: The optical fiber of the present invention has an input double-clad fiber containing high-reflection FBG, an oscillation double-clad fiber, and an output double-clad fiber containing low-reflection FBG. The output double-clad fiber is formed of a core, a first clad, and a second clad. In the output double-clad fiber, a high refractive-index resin coat section recoated with high refractive-index resin whose refractive index is the same as that of the second clad or greater is disposed at a part where the second clad is partly removed between an output end and the low-reflection FBG. The refractive index of the high refractive-index resin coat section gradually increases along the direction in which light travels through the first clad.

Abstract: Dry oxygen, dry air, or other gases such as ozone are hermetically sealed within the package of the external cavity laser or ASE swept source to avoid packaging-induced failure or PIF. PIF due to hydrocarbon breakdown at optical interfaces with high power densities is believed to occur at the SLED and/or SOA facets as well as the tunable Fabry-Perot reflector/filter elements and/or output fiber. Because the laser is an external cavity tunable laser and the configuration of the ASE swept sources, the power output can be low while the internal power at surfaces can be high leading to PIF at output powers much lower than the 50 mW.

Abstract: A mode-locked fiber laser has a resonator including a gain-fiber, a mode-locking element, and a spectrally-selective dispersion compensating device. The resonator can be a standing-wave resonator or a traveling-wave resonator. The dispersion compensating device includes only one diffraction grating combined with a lens and a minor to provide a spatial spectral spread. The numerical aperture of the gain-fiber selects which portion of the spectral spread can oscillate in the resonator.

Abstract: In aspects of the invention, wavelength conversion element has a harmonic generation portion and a parametric oscillation portion. The harmonic generation portion generates a harmonic of laser light output from a laser light source. The parametric oscillation portion generates signal light and idler light from the harmonic generated by the harmonic generation portion. In some aspects of the invention, electrodes and a first voltage control portion control the intensity of the harmonic generated by the harmonic generation portion. A first FBG (Fiber Bragg Grating) and a second FBG cause resonance of signal light output from the parametric oscillation portion. A piezo tube and a second voltage control portion change the resonance frequency of the first FBG and the second FBG.

Abstract: Apparatus and methods for altering one or more spectral, spatial, or temporal characteristics of a light-emitting device are disclosed. Generally, such apparatus may include a volume Bragg grating (VBG) element that receives input light generated by a light-emitting device, conditions one or more characteristics of the input light, and causes the light-emitting device to generate light having the one or more characteristics of the conditioned light.

Abstract: High-efficiency method and device, to produce coherent Smith-Purcell radiation. A conductive diffraction grating, delimited by two conductive walls, is used, and an electron beam is passed above the grating to generate the radiation. According to the invention, the speed of the electrons is sufficiently low in order that, in a diagram (wave number k, frequency f), the beam line (I) intersects a portion (V) of a branch of the dispersion relationship, located in the first Brillouin zone, and corresponding to the grating's fundamental mode, at a point (P) located outside the zone delimited by the light lines (III, IV), and the current density of the beam is sufficiently high to excite the grating's fundamental mode which is radiated towards the outside thereof.

Abstract: A wavelength tunable laser diode (LD) is disclosed. The LD provides a SG-DFB region and a CSG-DBR region. The SG-DFB region shows a gain spectrum with a plurality of gain peaks, while, the CSG-DBR region shows a reflection spectrum with a plurality of reflection peaks. The LD may emit light with a wavelength at which the one of the gain peaks and one of the reflection peaks coincides. In the present LD, both the gain spectrum and the reflection spectrum are modified by adjusting the temperature of the SG-DFB region and that of the CSG-DBR region independently.

Abstract: A swept wavelength light source is provided, the light source includes a semiconductor gain device operable to provide amplification, an optical retarding device, the retarding device having a block of material, a beam path with a well-defined beam path length being defined for light within the block of material produced by the gain device, a wavelength selector, and the gain device, the retarding device and wavelength selector being mutually arranged on the base so that a resonator is established for light portions emitted by the gain device and selected by wavelength selector; this does not exclude the presence of further elements contributing to the resonator, such as additional mirrors (including resonator end mirrors), lenses, polarization selective elements, other passive optical components, etc.; wherein the beam path in the retarding device is a part of a beam path of the resonator.

Abstract: The invention relates to a Q-switched laser comprised of a pump light source (1), an optical resonator accommodating a laser medium (6), and a passive Q-switch (5). It is the object of the present invention to provide an improved Q-switched laser which is of a simple and compact setup while having the least possible jitter of the repetition time. To achieve this target, the invention proposes that by means of a beam splitter (8) part of the light coupled out of the optical resonator is passed on to an optical delay line (9) and coupled back into the optical resonator upon having passed through the optical delay line (9).

Abstract: This disclosure is directed to widen an adjustable range of the spectral linewidth of laser light output from a laser apparatus. This laser apparatus may include: (1) an excitation source configured to excite a laser medium in a laser gain space, (2) an optical resonator including an output coupler arranged on one side of an optical path through the laser gain space and a wavelength dispersion element arranged on the other side of the optical path through the laser gain space, and (3) a switching mechanism configured to switch a beam-width magnification or reduction factor by placing or removing at least one beam-width change optical system for expanding or reducing a beam width in or from an optical path between the laser gain space and the wavelength dispersion element or by inverting orientation of the at least one beam-width change optical system in the optical path.

Abstract: A wavelength-tunable light source includes a quantum cascade laser that emits light from a first end and a second end, an optical system that collimates the light emitted from the first end, a first reflecting section on which the light collimated by the optical system is made incident, and a second reflecting section that partially reflects the light emitted from the second end of the quantum cascade laser and transmits the remaining light. The first reflecting section includes a plurality of diffractive gratings whose diffractive properties are different from each other and whose lattice plane directions are variable, and the first reflecting section diffracts a light at a particular wavelength corresponding to the diffractive property and the lattice plane direction of the selected diffractive grating in the direction opposite to the incident direction.

Abstract: A semiconductor laser has a first diffractive grating area. The first diffractive grating area has a plurality of segments. Each segment has a first area including a diffractive grating and a second area that is space area combined to the first area. Optical lengths of at least two of the second areas are different from each other. A refractive-index of each of the segments are changeable.

Abstract: An 830 nm broad area semiconductor laser having a distributed Bragg reflector (DBR) structure. The semiconductor laser supports multiple horizontal transverse modes of oscillation extending within a plane perpendicular to a crystal growth direction of the laser, in a direction perpendicular to the length of the resonator of the laser. The resonator includes a diffraction grating in the vicinity of the emitting facet of the laser. The width of the diffraction grating in a plane perpendicular to the growth direction and perpendicular to the length of the resonator is different at first and second locations along the length of the resonator. The width of the diffraction grating along a direction which is perpendicular to the length of the resonator increases with increasing distance from the front facet of the semiconductor laser.

Abstract: In one embodiment, the invention relates to systems, methods and devices for improving the operation of an electromagnetic radiation source or component thereof. In one embodiment, the source is a laser source. A Fourier domain mode locked laser can be used in various embodiments. The sources described herein can be used in an optical coherence tomography (OCT) system such as a frequency domain OCT system. In one embodiment, laser coherence length is increased by compensating for dispersion. A frequency shifter can also be used in one embodiment to compensate for a tunable filter induced Doppler shift.

Abstract: Provided is a wavelength-tunable external cavity laser module. The wavelength-tunable external cavity laser module includes: a gain medium generating light; an optical waveguide combined with the gain medium and including a Bragg grating and a thin film heater adjusting a temperature of the Bragg grating; and a high frequency transmission medium delivering a high frequency signal to the gain medium, wherein the high frequency transmission medium controls an operating speed of the light.

Abstract: An external-cavity one-dimensional multi-wavelength beam combiner that performs wavelength beam combining along a stacking dimension of a laser stack formed of a plurality of laser arrays, each laser array configured to generate optical radiation having a unique wavelength, and each of the plurality of laser arrays including one or more laser emitters arranged along an array dimension of the laser stack. The multi-wavelength beam combiner includes an optical imaging element configured to image each of the laser emitters along a slow axis of the laser emitters, an optical focusing element arranged to intercept the optical radiation from each of the plurality of laser arrays and combine the optical radiation along a stacking dimension of the laser stack to form a multi-wavelength optical beam, and a diffraction element positioned at a region of overlap of the optical radiation to receive and transmit the multi-wavelength optical beam.

Abstract: A method for manufacturing an optical fiber grating that includes first and second gratings that configure an optical resonator, the method including: forming the first grating by radiating ultraviolet light to an optical fiber so that a irradiation intensity Z satisfies the following Equation 1: Z?(??S/x+0.04556Y2+1.2225Y)/(0.05625Y2+1.6125Y) . . . Equation 1, where, Z represents an irradiation intensity (mJ/mm2) of the ultraviolet light, ??S represents the maximum shift amount of a reflection center wavelength of the first grating that is allowed as long as reflection wavelengths of the first grating and second grating overlap each other, x represents a shift amount of the reflection center wavelength per temperature change of 1° C. (nm/° C.) in the first grating, and Y represents an intensity (W) of the wave-guided light.

Abstract: A surface emitting laser is formed of a composition in which bandgap energy of layers from immediately above a current confinement layer to a second conductivity type contact layer is reduced towards the second conductivity type contact layer in a stacking direction, and a composition in which bandgap energy of layers from immediately below the current confinement layer to a first conductivity type contact layer is reduced towards the first conductivity type contact layer in a stacking direction while bypassing a quantum well layer or a quantum dot of an active layer, and includes a second conductivity type cladding layer including a material for reducing the mobility of carriers.

Abstract: A system and method for producing a kilowatt laser system having a post resonator including a polarization multi-plexer, optical reconfiguration element, anamorphic element and fiber-optic module configured to arrange a multi-wavelength profile for coupling into an optical fiber.

Abstract: A laser diode element assembly includes: a laser diode element; and a light reflector, in which the laser diode element includes (a) a laminate structure body configured by laminating, in order, a first compound semiconductor layer of a first conductivity type made of a GaN-based compound semiconductor, a third compound semiconductor layer made of a GaN-based compound semiconductor and including a light emission region, and a second compound semiconductor layer of a second conductivity type made of a GaN-based compound semiconductor, the second conductivity type being different from the first conductivity type, (b) a second electrode formed on the second compound semiconductor layer, and (c) a first electrode electrically connected to the first compound semiconductor layer, the laminate structure body includes a ridge stripe structure, and a minimum width Wmin and a maximum width Wmax of the ridge stripe structure satisfy 1<Wmax/Wmin<3.3 or 6?Wmax/Wmin?13.3.

Abstract: Disclosed is a distributed feedback semiconductor laser diode device capable of operating at a high output ratio of forward/backward optical power while ensuring satisfactory stability of single-mode oscillation. The distributed feedback semiconductor laser diode device is configured to include a diffraction grating formed in an optical waveguide thereof. In a partial region of the optical waveguide, there is formed an alternately repetitive pattern of a grating part possessing a distributive refractivity characteristic and a no-grating space part possessing a uniform refractivity characteristic. The no-grating space part possessing a uniform refractivity characteristic has an optical path length that is half an integral multiple of a wavelength of laser oscillation, and the grating part possessing a distributive refractivity characteristic includes at least five grating periods.

Abstract: Multi-pass optical imaging apparatus includes a concave mirror in combination with two retro-reflecting mirror pairs and at least one reflective surface. The mirror, the retro-reflecting mirror pairs and the reflecting surface are arranged such that a light-ray input into the apparatus parallel to and spaced apart from the optical axis of the concave mirror and incident on the concave mirror is caused to be incident on the thin-disk gain-medium at least four times, with each of the four incidences on the gain-medium being from a different direction. If the input ray is plane-polarized, the arrangement provides that the polarization orientation of the ray on each incidence on the gain-medium is in the same orientation.

Abstract: A laser device includes a substrate, a lower cladding layer on the substrate, an active layer on the lower cladding layer and having a disordered portion spaced from an end face of a resonator of the laser device, an upper cladding layer located on the active layer, and a diffraction grating located in a portion of a layer lying above or below the active layer, with respect to the substrate. The disordered portion intersects a boundary between a diffraction grating section, in which the diffraction grating is located, and a bulk section, in which no diffraction grating is located.

Abstract: An external cavity laser assembly (10) that generates a light beam (12) includes a gain medium (14) and a diffraction grating (24). The gain medium (14) has a growth direction (14C), a fast axis (14A), a first facet (34A), and a second facet (34B) that is spaced apart from the first facet (34A). The gain medium (14) emits from both facets (34A) (34B). Further, a beam polarization (30) of the light beam (32) emitting from the second facet (34B) is perpendicular to the growth direction (14C) and the fast axis (14A). The grating (24) includes a plurality of grating ridges (24A) that are oriented parallel to the beam polarization (30). Moreover, each of the grating ridges (24A) can have a substantially rectangular shaped cross-sectional profile.

Abstract: A Bragg grating has a local reflection strength which varies with position along the length of the grating so as to generate a non-uniform wavelength reflection spectrum, enabling compensation for a non-uniform gain profile of the gain section of a tunable laser. In another aspect, a Bragg comb grating is modulated by an envelope function which can also compensate for a non-uniform gain profile. The comb grating may be a phase change grating, with the envelope function shape being controlled by the length between phase changes and/or size of the phase changes.

Abstract: Techniques, devices and systems for optical communications based on wavelength division multiplexing (WDM) that use tunable multi-wavelength laser transmitter modules.

Abstract: A wavelength tunable filter and a wavelength tunable laser module are a codirectional coupler type whose characteristics do not vary significantly with a process error. They are structured so as to include a semiconductor substrate which has a first optical waveguide and a second optical waveguide. The first and the second optical waveguides are extended from a first side of the semiconductor substrate to an opposing second side thereof. The first optical waveguide includes a first core layer, which has a planar layout having periodic convexes and concaves, and a pair of electrodes, which vertically sandwich the first core layer. The second optical waveguide includes a second core layer, which has a lower refractive index than the first core layer. Further, a layer having the same composition and film thickness as the second core layer is placed under the first core layer.

Abstract: A semiconductor laser that has a reflective surface. The reflective surface redirects the light of an edge emitting laser diode to emit from the top or bottom surface of the diode. The laser may include a gain layer and a feedback layer located within a semiconductive die. The gain and feedback layers generate a laser beam that travels parallel to the surface of the die. The reflective surface reflects the laser beam 90 degrees so that the beam emits the die from the top or bottom surface. The reflective surface can be formed by etching a vicinally oriented III-V semiconductive die so that the reflective surface extends along a (111)A crystalline plane of the die.

Abstract: Fiber-laser light is Raman shifted to eye-safer wavelengths prior to spectral beam combination, enabling a high-power, eye-safer wavelength directed-energy (DE) system. The output of Ytterbium fiber lasers is not used directly for spectral beam combining. Rather, the power from the Yb fiber lasers is Raman-shifted to longer wavelengths, and these wavelengths are then spectrally beam combined. Raman shifting is most readily accomplished with a “cascaded Raman converter,” in which a series of nested fiber cavities is formed using fiber Bragg gratings.

Abstract: Optical resonators and optical devices based on optical resonators that implement diffractive couplers for coupling light with the optical resonators.

Abstract: One embodiment of a laser resonator comprises one or more laser resonator components, a container and an ozone generator. The laser resonator components include a non-linear crystal, a beam polarization combiner, an optical lens, a mirror and/or an optical grating. The container encloses the one or more laser resonator components. The ozone generator is configured to introduce ozone gas into the container.

Abstract: The invention relates to a laser light source for generating narrow-band laser radiation with high coherence, comprising a laser diode (1), which forms an internal resonator (4), and an external resonator (7) coupled to the internal resonator (4). The object of the invention is to improve a laser source of the kind such that it generates narrow-band and coherent laser radiation with high output power and at the same time with high long-term stability. Furthermore, the laser light source is to be produced in a cost-effective manner. The object is achieved by the invention in that the laser diode (1) runs in an operating mode in which multimode laser radiation is generated, comprising a plurality of spectrally neighboring resonance modes (9) of the external resonator (7). The resonance modes are selected by adapting the spectral characteristics of the external (7) and internal (4) resonators.

Abstract: A gain module, operative to output a laser light coupled into a laser system, is structured with at least one gain element radiating the laser light and a spectrally-selective element. The spectrally-selective element includes a slab of photosensitive material and two parallel feedback and isolating Bragg mirrors recorded in the slab. The feedback Bragg mirror is operative to provide a wavelength-dependent feedback so as to cause the laser chip to generate the laser light at the resonance wavelength of the feedback Bragg mirror. The isolating Bragg mirror is automatically adjusted to retroreflect a backreflected signal light, which is generated by the laser system at a signal wavelength different from the resonance wavelength, upon positioning the feedback mirror orthogonally to the laser light.

Abstract: In one general embodiment, a thin film structure includes a substrate; a first corrosion barrier layer above the substrate; a reflective layer above the first corrosion barrier layer, wherein the reflective layer comprises at least one repeating set of sub-layers, wherein one of the sub-layers of each set of sub-layers being of a corrodible material; and a second corrosion barrier layer above the reflective layer. In another general embodiment, a system includes an optical element having a thin film structure as recited above; and an image capture or spectrometer device. In a further general embodiment, a laser according to one embodiment includes a light source and the thin film structure as recited above.

Abstract: An embodiment of the invention relates to a device comprising a laser and a waveguide stripe or netlike hexagonal stripe structure, which allows propagation of multitude of the lateral modes in the waveguide stripe or stripe structure, wherein the waveguide stripe has at least one corrugated edge section along its longitudinal axis to provide preferable amplification of the fundamental lateral mode or in-phase supermode and to obtain high brightness of the emitted radiation.

Abstract: A laser device, includes: a fundamental wave generating portion configured to generate a plurality of fundamental waves having wavelengths which are different from each other in at least one set thereof, the fundamental wave generating portion having a semiconductor laser having a plurality of luminous points, and a Bragg reflection structure; and a nonlinear optical element in which a poling structure adapted to pseudophase matching for the wavelengths of the plurality of fundamental waves emitted from the fundamental wave generating portion, respectively, is formed variatively along a propagating direction of the plurality of fundamental waves.

Abstract: A line narrowed gas discharge laser system and method of operating same is disclosed which may comprise a dispersive center wavelength selective element; a beam expander comprising a plurality of refractive elements; a refractive element positioning mechanism positioning at least one of the refractive elements to modify an angle of incidence of a laser light beam on the dispersive center wavelength selection element; each of the dispersive center wavelength selection element and the beam expander being aligned with each other and with a housing containing at least the dispersive center wavelength selection element; a housing positioning mechanism positioning the housing with respect to an optical axis of the gas discharge laser system. The dispersive element may comprise a grating and the beam expander may comprise a plurality of prisms. The housing may contain the dispersive center wavelength selective element and the beam expander. The housing positioning element may comprise a position locking mechanism.

Abstract: A laser device includes a substrate, a lower cladding layer on the substrate, an active layer on the lower cladding layer, an upper cladding layer on the active layer, and a second order diffraction grating in a layer above the active layer and having dimensions of at least 100 ?m by 100 ?m. The second order diffraction grating diffracts and directs light generated in the active layer in a direction generally perpendicular to the longitudinal direction of the upper cladding layer. A laser device further includes a first reflective film on a first end face of a resonator, and a second reflective film on a second end face of the resonator, the second end face being located at the opposite end of the resonator to the first end face.

Abstract: Provided is a wavelength tunable external cavity laser (laser beam) generating device. The wavelength tunable external cavity laser generating devices includes: an optical amplifier, a comb reflector, and an optical signal processor connected in series on a first substrate; and an external wavelength tunable reflector disposed on a second substrate adjacent to the first substrate and connected to the optical amplifier, wherein the comb reflector includes: a waveguide disposed on the first substrate; a first diffraction grating disposed at one end of the waveguide adjacent to the optical amplifier; and a second diffraction grating disposed at the other end of the waveguide adjacent to the optical signal processor, wherein the optical amplifier, the comb reflector, and the optical signal processor constitute a continuous waveguide.

Abstract: In accordance with the present invention, a compact laser system with nearly continuous wavelength scanning is presented. In some embodiments, the compact laser system can be scanned over a broad range. In some embodiments, the compact laser system can be scanned at high scan rates. In some embodiments, the compact laser system can have a variable coherence length. In particular, embodiments with wavelength scanning over 140 nm with continuously variable scan rates of up to about 1 nm/?s, and discrete increase in scan rates up to about 10 nm/?s, and variable coherence lengths of from 1 mm to about 30 mm can be achieved.

Abstract: High-power, phased-locked, laser arrays as disclosed herein utilize a system of optical elements that may be external to the laser oscillator array. Such an external optical system may achieve mutually coherent operation of all the emitters in a laser array, and coherent combination of the output of all the lasers in the array into a single beam. Such an “external gain harness” system may include: an optical lens/mirror system that mixes the output of all the emitters in the array; a holographic optical element that combines the output of all the lasers in the array, and an output coupler that selects a single path for the combined output and also selects a common operating frequency for all the coupled gain regions.

Abstract: The present invention includes a vertical-cavity surface-emitting semiconductor laser diode having a resonator with a first distributed Bragg reflector, an active zone which has a p-n junction and is embedded into a semiconductor layer sequence, and a second distributed Bragg reflector. The semiconductor laser diode has an emission wavelength ?, wherein a periodic structure is arranged within the resonator as an optical grating made of semiconductive material and dielectric material, the main plane of extension of which is arranged substantially perpendicularly to the direction of emission of the semiconductor laser diode. The periodic structure is in direct contact with at least one of the semiconductor layers embedding the active zone and with at least one of the two distributed Bragg reflectors.

Abstract: A device having a light cavity includes, at one end, a plasmonic reflector having a grating surface for coupling incoming light into traverse plasmon waves and for coupling the traverse plasmon wave into broaden light, the surface serving to redistribute light within the cavity, the reflector being well suited for use in laser diodes for redistributing filamental cavity laser light into spatially broaden cavity laser light for translating multimodal laser light into unimodal laser light for improved reliability and uniform laser beam creation.

Abstract: A wavelength tunable laser includes a DFB portion including a first optical waveguide provided with a first grating; a DBR portion including a second optical waveguide that is optically coupled to the first optical waveguide and is provided with a plurality of second gratings continuously arranged in a waveguide direction; and a phase shift portion including a third optical waveguide that is optically coupled to the first and second optical waveguides. Each of the second gratings has a grating formation area in which a grating is formed, and a grating phase shift area which shifts the phase of the grating adjacent thereto in the second grating.

Abstract: External cavity laser (ECL) systems and methods for measuring the wavelength of the ECL by using a portion of the positional light received by the position sensitive detector (PSD) to determine the position of a wavelength tuning element (such as a diffraction grating or an etalon), for determining the longitudinal laser mode or power output of the laser from a portion of the laser light received by a beam-shearing mode sensor, and by using a non-output beam(s) from a transmissive diffraction grating in the ECL to monitor the external cavity laser.