Abstract: An excimer laser apparatus using a bandwidth-narrowing optical system including a beam diameter-enlarging optical system and a Littrow mounting reflection type diffraction grating is made suitable for use as a laser light source for semiconductor lithography or the like by surmounting the limit to bandwidth narrowing due to wavefront distortion induced by the reflection type diffraction grating. In an excimer laser apparatus having a bandwidth-narrowing optical system including a Littrow mounting reflection type diffraction grating and a combination of a beam diameter-enlarging optical system and a slit placed on the entrance side of the reflection type diffraction grating, diffracted wavefront distortion (a measured value for He—Ne laser light) within the laser irradiation area of the reflection type diffraction grating in Littrow mounting is not more than &lgr;/10, where &lgr; is a measuring wavelength.

Abstract: The invention relates to a device for generating a plurality of laser beams. The device comprises: a laser source emitting an initial beam at P wavelengths; a wavelength splitter assembly for splitting the initial beam into N intermediate beams where N≦P, each intermediate beam containing a group of wavelengths comprising at least one wavelength; and N′ energy splitter assemblies where N′≦N for splitting an intermediate beam into ni divisional beams, each of the ni divisional beams having substantially the same energy, whereby K divisional beams are obtained with K = N - N ′ + ∑ i = 1 i = N ′ ⁢ n i .

Abstract: A tunable laser is provided having a gain medium and a resonator for generating a laser beam, and an angular dispersion element. The laser further includes a beam expander with adjustable magnification for adjusting an angular dispersion provided by the dispersion element. The adjustable beam expander preferably includes one or two rotatable prisms. When two prisms are used, the prisms are preferably synchronously rotatable according to a preset ratio such that any changes in refraction angle due to the rotation of the first prism are automatically compensated by the rotation of the second prism. A single prism may serve both as a dispersion element and as a beam expansion element. A processor preferably monitors the linewidth and wavelength of the output beam and adjusts an orientation of the prism or prisms of the expansion unit, and the tilt of either a reflection grating or a highly reflective mirror of the resonator in a feedback loop.

Abstract: A laser apparatus and method with compact cavity design that provides suppression of source spontaneous emission (SSE) and amplified spontaneous emission (ASE) light with minimal loss. The laser comprises a gain medium emitting a light beam along an optical path, a tuning element positioned in the optical path and configured feed back light of a selected wavelength to the gain medium and configured to define a first output beam directed along a first output path, a partial reflector located in the optical path and positioned to create a second output beam directed along a second output path substantially parallel to the first output path; and having a spontaneous emission component that is spatially separated from the selected wavelength. The second output beam can be coupled into optical fiber and produce a coherent light source with high spectral purity and tunable wavelengths.

Abstract: An integrated or hybrid-optical device (10) able to perform the functions of both a beam splitter and an etalon. A splitter interface (72), front-cavity interface (74), and rear-cavity interface (76) are provided and separate regions (78, 80, 82, 84) which may be of “air” (gas or vacuum) or solid materials. The front-cavity interface (74), the rear-cavity interface (76), and the interposed third region (82) define a Fabry Perot etalon, which may be either solid or air-spaced. In particular, the integrated optical device (10) has only the second region (80) interposed between the splitter interface (72) and the front-cavity interface (74).

Abstract: A fiber-optic laser source capable of emitting one useful wavelength at a given time, electrically step-tunable to the ITU grid wavelengths, is disclosed. The laser preferably comprises a diode-pumped rare-earth doped fiber amplifier as gain medium, a periodic filter to define ITU grid lasing wavelengths, and a tunable filter electrically step tunable to any wavelength defined by the periodic filter. The arrangement is enclosed in a ring single mode optical fiber resonator. The ring resonator may be made, in part or in total, with polarization-maintaining optical fiber. The resonator also comprises in-line optical isolators to ensure unidirectional operation and to eliminate undesired reflections. A polarization controller and polarizer device and a gain-flattening filter may also be included within the resonator depending on the desired output characteristics of the laser. The laser may be designed to operate in single cavity longitudinal mode.

Abstract: An excimer or molecular fluorine laser system includes a discharge chamber filled with a laser gas mixture at least including a halogen gas and a buffer gas, a plurality of electrodes within the discharge chamber connected to a power supply circuit for energizing the gas mixture, and a resonator for generating a laser beam including a line-narrowing module on one side of the discharge chamber for reducing a bandwidth of the laser beam. The laser beam is output coupled from the resonator on the same side of the discharge chamber as the line-narrowing module and preferably after the beam is line-narrowed at the line-narrowing module. A substantially total intensity of the laser beam impinges upon a line-narrowing optical element of the line-narrowing module and is thereby line-narrowed. The resonator preferably includes at least one aperture for reducing a bandwidth of the laser beam.

Abstract: A system and method for laser beam coupling between waveguide optics uses extension members to reduce power losses in a laser beam traveling within a resonator cavity of the laser beam. In some embodiments, the extension members are made of electrically conducting material and are spaced from longitudinal ends of electrodes by electrically insulating material. The electrically insulating material is sized to prevent electrical discharge from occurring between the electrode and the extension member adjacent thereto. In other embodiments, the extension members are fashioned from a lasing medium such as from a solid-state crystal lasing medium.

Abstract: In order to facilitate control of the polarization plane of a laser beam emerging from a surface-emitting-type semiconductor laser in a specific direction and to suppress occurrence of fluctuations and switching of the polarization plane depending on the optical output and the environmental temperature, a strain generating section (19) is arranged adjacent to a resonator (10B) of a semiconductor laser. The strain generating section (19) impresses anisotropic stress to the resonator (10B) to generate strain, resulting in birefringence and dependence of the gain on the polarization in the resonator (10A). This enables stabilized control of the polarization plane.

Abstract: A micro-laser is disclosed which includes a waveguide, a first and a second subwavelength resonant grating in the waveguide, and at least one photonic band gap resonant structure (PBG) in the waveguide and at least one amplifying medium in the waveguide. PBG features are positioned between the first and second subwavelength resonant gratings and allow introduction of amplifying mediums into the highly resonant guided micro-laser microcavity. The micro-laser may be positioned on a die of a bulk substrate material with one or more electronic and optical devices and may be communicably connected to the same. A method for fabricating a micro-laser is disclosed. A method for tuning the micro-laser is also disclosed. The micro-laser may be used as an optical regenerator, or a light source for data transfer or for optical computing.

Abstract: Harmonic lasers are provided. A third harmonic laser includes a first high reflector and an output coupler forming a resonator cavity having an optical axis. The resonator cavity includes a laser medium for producing a fundamental beam. Desirably, the laser medium is Nd:YAG, Nd:YLF, Nd:YV04, although other laser mediums are also contemplated such as Ti:sapphire, Nd:YAB and the like. The laser medium can be pumped by any desired source for example laser, laser diode, laser diode bar, fiber coupled laser diode bar or lamp which are well known in the art. The laser medium can be either end pumped or side pumped which are also well known. The first high reflector is reflective of a fundamental beam. A second harmonic generator is located within the cavity formed between the first high reflector and the output coupler for generating a second harmonic beam from the fundamental beam. The output coupler is highly transmissive for second harmonic beam and partially transmissive for a fundamental beam.

Abstract: According to the invention, a high power diode pumped solid state laser is provided. The laser includes a first and second reflective surfaces which form an optical resonator cavity. A laser medium, particularly a Nd doped laser medium for example: a Nd:YAG, a Nd:YLF, or a Nd:YVO4 crystal is provided within the laser cavity. A fundamental frequency laser beam propagates from the front and back ends of the laser medium. The first reflective surface is highly reflective for fundamental beam. The second reflective surface is at least partially reflective for fundamental beam. The laser medium is end pumped by at least one diode pumping apparatus for example, a laser diode, or diode array, or fiber coupled laser diodes, whose wavelength matches at least one laser medium absorption band. The diode pumping apparatus is located adjacent either the front end or the back end of the laser medium, or both. The optical resonator cavity is configured to provide a laser beam diameter in the laser medium from about 0.

Abstract: A high power diode laser array system utilizes an external cavity to narrow the spectral width of a high power diode laser array to change the output power normally produced by the diode array from a broad spectrum to a very narrow spectrum. The power output of the laser array system is concentrated over a narrow spectral range which falls within the useable range for particular applications such as optical pumping of noble gas samples for magnetic resonance imaging. The output of the array is received by a collimating element, which collimates the light in a direction perpendicular to the direction of the length of the array of emitters and directs the light on a beam path to a diffraction grating which is oriented at an angle to the incident beam.

Abstract: A solid laser produces a laser beam of a 1 &mgr;m wavelength band with an Nd-doped solid laser medium. An oscillation mode is brought to a single longitudinal mode with a Fabry-Pérot etalon located within a resonator. An etalon thickness, an etalon reflectivity, an etalon inclination, and a resonator longitudinal mode interval satisfy the relationships, 1.2%≦RN≦15% and 0.5°≦&thgr;≦2.0°, in which RN represents an effective reflectivity of the etalon with respect to wavelengths &lgr;=&lgr;0±&Dgr;&lgr;c deviating by a resonator longitudinal mode interval &Dgr;&lgr;c from a resonance wavelength &lgr;0 of the etalon, and &thgr; represents an inclination of an etalon optical axis with respect to a resonator optical axis.

Abstract: Continuously tunable and precisely wavelength-switchable fiber lasers combine fiber Bragg gratings and the transmissive filtering properties of high finesse fiber Fabry-Perot filters. This laser arrangement adapts to multiple wavelength ranges based on the selections of fiber Bragg grating and gain medium and their arrangement to create a wavelength-modulatable and simultaneously rapidly wavelength-switchable narrow linewidth all-fiber laser design. This laser arrangement further results in narrow-linewidth outputs with fast switching speeds between the selected wavelengths.

Abstract: A passively cooled solid-state laser system for producing high-output power is set forth. The system includes an optics bench assembly containing a laser head assembly which generates a high-power laser beam. A laser medium heat sink assembly is positioned in thermal communication with the laser medium for conductively dissipating waste heat and controlling the temperature of the laser medium. A diode array heat sink assembly is positioned in thermal communication with the laser diode array assembly for conductively dissipating waste heat and controlling the temperature of the laser diode array assembly. The heat sink assemblies include heat exchangers with extending surfaces in intimate contact with phase change material. When the laser system is operating, the phase change material transitions from solid to liquid phase.

Abstract: The cavity of the invention has a pumping source, a ring cavity, a planar convex lens, an optical gain medium, and/or a nonlinear medium. The laser cavity is formed by two mirrors with the same curvature. The curving surfaces of the two mirrors are coupled by a manner of face to face, whereby a space is defined as the ring cavity. The planar-convex lens is located between the pump beam and the ring cavity to work together with the two mirrors of the ring cavity to focus the pump beam. The pumping light enters the ring cavity at a desired distance of d mm from the mirror axis. The laser light also enters the ring cavity in a propagating direction nearly parallel to the mirror axis. Due to the two curving surfaces of the two mirrors, the light beam is reflected back and forth to form the 3-D figure-“8” light path. The optical gain medium and the nonlinear medium are located between the two mirrors on the light path.

Abstract: A system and method is provided to calibrate a transmission laser, such as a widely tunable laser (WTL), within a dense wavelength division multiplexer (DWDM) for transmission through an optic fiber. The WTL is tuned to the ITU grid using an etalon and a gas cell. The absolute transmission wavelengths of the WTL are calibrated by routing a WTL output beam through the etalon and through the gas cell while varying tuning parameters of the WTL to generate an etalon spectrum and a gas absorption spectrum, both as functions of the tuning parameters. The etalon and gas absorption spectra are compared, along with input reference information specifying gas absorption as a function of absolute wavelength, to determine the absolute transmission wavelength for the WTL as a function of the tuning parameters. The WTL is then tuned to align the transmission wavelength of the WTL to an ITU transmission grid line.

Abstract: A laser cavity comprising a gain medium and first and second end mirrors, wherein the laser cavity further comprises a birefringent material and a mirror arranged to fold light propagating within the laser cavity through a predetermined angle, wherein the predetermined angle is selected such that the reflectivity of the fold mirror is polarisation dependent, and the birefringence of the birefringent material co-operates with the polarisation dependent reflectivity of the fold mirror to form a Lyott filter which suppresses oscillation of unwanted laser modes. The invention allows the construction of a low loss, high finesse laser cavity with longitudinal mode control. The need for introduction of an extra polarisation selection element to form a Lyott filter is removed.

Abstract: Embodiments of a wavelength tunable optical coupler, integrated optical components, and lasers are disclosed. The tunable optical coupler, the integrated optical components, and the lasers include thermo-optic organic material that has an index of refraction which can quickly vary in response to changes in temperature. By controlling the temperature in the thermo-optic organic material through the use of heaters or coolers, the optical coupler, the integrated optical components, and the lasers can be quickly and selectively tuned over a broad range of wavelengths with high spectral selectivity.

Abstract: An excimer or molecular fluorine laser includes a gain medium surrounded by a resonator and including a line-narrowing module preferably including a prism beam expander and one or more etalons and/or a grating or grism within the resonator. The material of transmissive portions of the line-narrowing module including the prisms and the plates of the etalons comprises a material having an absorption coefficient of less than 5×10−3/cm at 248 nm incident radiation, less than 10×10−3/cm at 193 nm incident radiation, and less than 0.1/cm at 157 nm. Preferably the material also has a thermal conductivity greater than 2.0 W/m° C.

Abstract: Laser source comprising a first active arm extending from a first end reflector up to a dispersing system grid and containing an amplifier medium that produces a first luminous beam. A second passive arm extends from the grid to a second end reflector, the grid generating a second beam by diffraction of the first beam, wherein the second end reflector closes the second passive arm and is partially reflecting to enable extraction of a luminous flux. An optical component produces, from the second beam, a third beam translated and antiparallel, to return to the grid which, by diffraction, forms a fourth beam translated and antiparallel to the first beam.

Abstract: In the wavelength-division-multiplexed optical transmission, laser diodes of the number of multiplicity are disposed as a light source to configure a transmitter. However, since this method requires a large number of light sources and highly precise wavelength control, a cost and an apparatus are increased. An ultrashort pulse solid-state laser is used as the light source of the transmitter and its wide spectrum is taken out by a splitter to be assigned to each channel, so that the number of light sources can be reduced greatly. The transmitter requires high repetition rate such as 2.4 GHz, 10 HGz and the like as the repetition rate of the ultrashort pulse solid-state laser, while by configuring the resonator only by two components as shown in FIG. 1, the high repetition rate can be attained. Since each channel is produced passively from the splitter, very precise wavelength management is not required. The light source is made small and the number thereof is reduced.

Abstract: An F2-excimer laser has multiple closely-spaced spectral lines of interest around 157 nm, and one of the lines is selected by wavelength selection optics. The wavelength selection optics of a first preferred embodiment include a birefringent Brewster window enclosing the laser gas volume of the discharge chamber. The window preferably comprises MgF2 and is located at one end of the discharge chamber. One line is selected of the two when the optical thickness of the window is selected in coordination with rotatably adjustable, orthogonal refractive indices of the window. The transmissivity of the window is dependent on the orthogonal refractive indices and the optical thickness of the window. The wavelength selection optics of a second preferred embodiment include are at least partially within the laser active volume. In this way, line selection is performed in a manner which optimizes the combination of optical and discharge efficiency, resonator size and cost.

Abstract: An external cavity laser comprises a light source unit, preferably comprising a semiconductor light source having internal optical gain and a collimating lens, for supplying substantially collimated light to a retroreflector via an angle-tuned filter extending across an optical axis of the light source. The retroreflector is positioned so as to receive light from the light source via the angle-tuned filter and reflect the light via the angle-tuned filter back to the light source. The retroreflector may comprise a quarter pitch graded-index (GRIN) lens having a proximal end surface oriented towards the light source and a distal end surface opposite thereto, with a mirror provided on the distal end surface, preferably as a high-reflectance coating. The angle-tuned filter may be attached to the proximal end surface of the GRIN lens, preferably as a coating. The GRIN lens may be tilted in order to vary the angle of the filter relative to the optical axis and hence the wavelength.

Abstract: An excimer or molecular fluorine laser includes a discharge chamber filled with a gas mixture, multiple electrodes within the discharge chamber connected to a power supply circuit for energizing the gas mixture, and a resonator including the discharge chamber and a pair of resonator reflectors for generating an output laser beam. The resonator includes an interferometric device, which may be a resonator reflector such as an output coupling interferometer or HR reflector, or a transmissive intracavity component, including a pair of opposing reflecting surfaces tuned to produce a response maximum at a selected wavelength for narrowing a linewidth of the output laser beam. One of the pair of opposing reflecting surfaces is preferably configured such that the opposing reflecting surfaces of the interferometer have a varying optical distance therebetween over an incident beam cross-section which serves to suppress at least one side band or outer portions of the response maximum to reduce spectral purity.

Abstract: A laser resonator and an associated method are provided which produce a laser beam having a relatively uniform intensity profile following a single pass through a single laser cavity. The laser resonator includes a laser cavity through which a chemical medium flows from an upstream end to a downstream end. The laser resonator also includes a first optical element, typically termed a secondary mirror, for directing an expanding laser beam across the cavity. The laser resonator also includes a second optical element disposed opposite the first optical element relative to the laser cavity. Typically, the second optical element is a set of primary mirrors and, more particularly, a pair of primary mirrors for both collimating and spatially inverting the laser beam relative to the predetermined flow direction of the chemical medium through the laser cavity. Once the expanded laser beam has been collimated and spatially inverted, the laser beam is redirected across the laser cavity.

Abstract: A an apparatus for locking a bending mechanism that bends a reflex type wavelength selection element for a bending mechanism that bends a reflex type wavelength selection element comprises a locking assembly. The locking assembly locks the bending mechanism. This allows maintaining the configuration of the reflex type wavelength selection element with the element being bent by the bending mechanism according to curvature of wavefront of an incident laser beam. Therefore, it is possible to stabilize the performance of wavelength selection in the reflex type wavelength selection element, even though the laser device receives vibration and shock.

Abstract: A wavelength measurement system uses birefringent material waveplate, thereby producing a substantially sinusoidal spectral response. As a result, the responses of multiple birefringent filters can be combined to yield a filter system with a periodic frequency response that has an additive wavelength resolution that is spectrally stable. That is, the wavelength measurement system does not have regions where wavelength resolution is degraded. In one implementation, a waveplate system 112 is used, placed between two blocks of birefringent material 110 and 114. A quadrant detector 116 is used to detect the intensities of the resulting four beams.

Abstract: A narrow band molecular fluorine laser system includes an oscillator and an amplifier, wherein the oscillator produces a 157 nm beam having a linewidth less than 1 pm and the amplifier increases the power of the beam above a predetermined amount, such as more than one or several Watts. The oscillator includes a discharge chamber filled with a laser gas including molecular fluorine and a buffer gas, electrodes within the discharge chamber connected to a discharge circuit for energizing the molecular fluorine, and a resonator including the discharge chamber for generating a laser beam having a wavelength around 157 nm. Line-narrowing optics are included intra- and/or extra-resonator for reducing the linewidth of the laser beam to less than 1 pm. The amplifier may be the same or a different discharge chamber, and optical and/or electronic delays may be used for timing pulses from the oscillator to reach the amplifier at a maximum in the discharge current of the amplifier.

Abstract: The present invention is directed to a pulsed, mode-locked, picosecond laser having a solid-state laser medium, a saturable absorber (SA), and a passive negative feedback (PNF) element. The SA is “slow”, having an absorption recovery time which is longer than a desired duration of an output pulse. The SA and the PNF element together mode-lock the laser to produce an output pulse or pulses of the desired duration. Thus, according to the method of the invention, the solid-state laser medium is energized, whereupon the laser becomes mode-locked to produce the desired output pulses. The solid-state laser of the present invention is capable of producing very short, energetic output pulses, such as output pulses having a duration on the order of one or more picoseconds, and an energy of from about 100 &mgr;J to about 2 mJ. These output pulses are very stable. As the laser is of relatively simple construction, it is relatively easy to operate to produce this stable energy output.

Abstract: An integrated diffraction grating semiconductor laser device having an active layer configured to radiate light, a light reflecting facet positioned on a first side of the active layer, and a light emitting facet positioned on a second side of the active layer thereby forming a resonator between the light reflecting facet and the light emitting facet. A diffraction grating is positioned within the resonator along the length of the active layer. At least one of the light reflecting and light emitting facets is horizontally offset by an offset angle with respect to the light emitting direction of the laser device so as to reduce the reflectivity of the facet and suppress Fabry-Perot oscillations.

Abstract: Diamonds are marked by a laser beam having a characteristic that is changeable by positioning a selected aperture in the beam within a resonant cavity of a laser source. Guidelines are positioned in advance on the diamonds, and the marking is subsequently performed between the guidelines.

Abstract: An optical configuration to illuminate an etalon in a laser wavemeter with a minimum level of light intensity. The system includes optical components to direct a portion of the laser output beam representing the entire cross section of the beam, through an etalon positioned in an etalon housing and onto a photodetector. A first lens condenses the size of the beam sample, and a second lens re-collimates the beam which then passes into the etalon housing, ensuring that all of the spatial components of the beam are adequately sampled. A diffractive diffusing element is incorporated into the optical path. In a preferred embodiment, the diffractive diffusing element is placed within the etalon housing between said plano-concave lens and the etalon. In another preferred embodiment, the diffusing element is located up stream but outside the housing in the optical path.

Abstract: A laser apparatus has a function to easily select a component having a wavelength near to an oscillated wavelength of a laser beam from among components of a reference beam having a spectral distribution, which is already known, as a reference in measurement of the oscillated wavelength of the laser beam. The laser apparatus has a laser oscillator for outputting a laser beam, a reference light source for outputting a reference beam having a spectral distribution which is already known, two spectrum separation units having different resolving power, a detecting device for detecting a part of the laser beam and a part of the reference beam separated by the two spectrum separation units, and a control unit for measuring an oscillated wavelength of the detected laser beam by using as a reference a component selected from among components of the detected reference beam and having a wavelength near to the oscillated wavelength of the detected laser beam.

Abstract: The present invention provides a light source for an optical network. The light source includes a semiconductor optical gain element, having an axis of symmetry; and a mechanism for reflecting wavelengths that correspond to optical transmission channels of the optical network, the reflecting means optically coupled to the semiconductor optical gain element and intersecting the axis of symmetry. The light source of the present invention is a single multi-wavelength light source. It is designed to only emit wavelengths that specifically correspond to optical transmission channels. The mechanism of the light source suppresses possible mode hopping, thus maintaining the power stability of all channels. Since multiple wavelengths are provided in a single light source, the number of lasers required to service a network can be dramatically reduced, increasing efficiency and reducing the cost of equipment and time for maintenance as well.

Abstract: The present invention provides a continuously tunable external cavity laser (ECL) with a compact form factor and precise tuning to a selected center wavelength of a selected wavelength grid. The ECL may thus be utilized in telecom applications to generate the center wavelengths for any channel on the ITU or other optical grid. The ECL does not require a closed loop feedback. A novel tuning mechanism is disclosed which provides for electrical or mechanical tuning to a known position or electrical parameter, e.g., voltage, current or capacitance, with the required precision in the selected center wavelength arising as a result of a novel arrangement of a grid generator and a channel selector. The grid generator exhibits first pass bands which correspond to the spacing between individual channels of the selected wavelength grid and a finesse which suppresses side band modes of the laser. The channel selector exhibits second pass bands that are wider than the first pass bands.

Abstract: A band narrowing laser having a band narrowing module which narrows by a band narrowing element a band of the laser beam generated from a laser medium, in which wavefront correction means (10) that corrects the wavefront of an incident laser beam and and projects the corrected beam is intalled in the band narrowing module (6) to produce a laser beam with a narrow and stable spectral line width.

Abstract: A laser marker includes a collimator lens converting laser light emitted from a broad area semiconductor laser into substantially parallel beams of light, a cylindrical concave lens permitting to pass therethrough the laser light having passed through the collimator lens and being perpendicular to a plane of an active layer of the semiconductor laser, the cylindrical concave lens serving as a concave lens for the laser light having passed through the collimator lens and being parallel to the plane of the active layer, a cylindrical convex lens permitting to pass therethrough the laser light having passed through the concave lens and being perpendicular to the plane of the active layer of the semiconductor laser, the cylindrical convex lens serving as a convex lens for the laser light having passed through the collimator lens and being parallel to the plane of the active layer, and a focusing lens focusing the laser light having passed through the cylindrical convex lens.

Abstract: A fixed wavelength, external cavity semiconductor laser comprises a semiconductor laser gain medium and an intra-cavity filter having a filter function specifying a frequency of operation of the laser. This distinguishes it from distributed feedback Bragg reflector systems in which the wavelength of operation is dictated by the semiconductor Bragg grating, drive current, and temperature. A cavity length modulation system is further provided that modulates an optical length of the cavity to change the spectral locations of longitudinal modes of the cavity relative to the filter function. One important advantage of the present invention is that it can be deployed without a thermoelectric (TE) cooler. Specifically, the intra-cavity filter material in combination with the cavity length controller, allow a mode of cavity to be located at the filter function.

Abstract: The invention relates to apparatus and methods for tuning the wavelength of a laser. According to one embodiment, the wavelength tunable filter includes a first wavelength selective element having a first thickness, a first refractive index and a first spectral response having a plurality of transmission peaks having an associated first period. The filter also includes a second wavelength selective element having a second thickness, a second refractive index and a second spectral response having a plurality of transmission peaks having an associated second period. Additionally, the filter includes a control module to vary at least one of the first thickness, the second thickness, the first refractive index, and the second refractive index such that one of the plurality of transmission peaks of the first spectral response substantially overlaps one of the plurality of transmission peaks of the second spectral response.

Abstract: A laser for delivering laser radiation at a selected one of a plurality of equally-spaced frequencies extending over a frequency range includes a laser resonator defined by two end mirrors. The resonator includes a surface-emitting semiconductor multilayer gain-structure in optical contact with one of the mirrors. A third mirror located in the laser resonator forms an etalon with that mirror. The third mirror is movable for adjusting a peak transmission frequency of the etalon to align with the selected frequency. The resonator end mirrors are spaced apart by an optical distance selected such that the frequency and frequency-spacing of possible longitudinal lasing modes of the resonator correspond with the plurality of equally-spaced frequencies. When the peak transmission frequency of the etalon is aligned with the selected frequency the laser resonator delivers radiation in a single longitudinal mode at the selected frequency.

Abstract: An apparatus for combining the outputs from multiple gain elements of an array within a single resonator cavity to achieve a predetermined spectral output or improved output power is provided. The resonator cavity is comprised of a reflector, preferably deposited on the back facets of the gain element array, and an output coupler. Interposed between the gain element array and the output coupler are an optical element and a reflective diffraction grating. The optical element can be comprised of either a GRIN lens or a uniform index element with a shaped, reflectively coated back surface. The output coupler can be directly coupled to an optical fiber, for example by burying the output coupler into the entrance aperture of the fiber.

Abstract: An optical feedback assembly includes a filter and a partial reflector that can stabilize and center the optical output of a laser on a specific wavelength region. The partial reflector, such as a half mirror, can be placed adjacent to the laser while the filter can be disposed between the partial reflector and the laser. Because of its relative location to the lasing cavity of a laser, the optical feedback assembly may be characterized as form of “external cavity feedback” for the laser. The optical feedback assembly is well suited for optical networks in general and for dense wavelength division multiplexing applications.

Abstract: A stray light cutting structure for an optical device provided with an optical component through which a predetermined light beam travels in parallel to the optical axis of the optical device is provided. The structure is for cutting stray light, which travels at an angle to the optical axis of the optical device to enter the optical component through one end face thereof, and includes at least one notch formed on one side face of the optical component.

Abstract: Techniques and devices for sensing a sample by using a whispering gallery mode resonator.

Abstract: A system is provided for delivering a laser beam of wavelength less than 200 nm from a laser, such as an F2 laser or ArF laser, through a sealed enclosure sealably connected to the laser, and preferably to another housing, leading ultimately to a workpiece. The enclosure is preferably evacuated and back-filled with an inert gas to adequately deplete any air, water, hydrocarbons or oxygen within the enclosure. Thereafter or alternatively, an inert gas flow is established and maintained within the enclosure during operation of the laser. The inert gas preferably has high purity, e.g., more than 99.5% and preferably more than 99.999%, wherein the inert is preferably nitrogen or a noble gas. The enclosure is preferably sealed by a window transparent to the sub-200 nm radiation for preventing contaminants generated in the enclosure from entering the housing and contaminating surfaces therein. The enclosure is preferably made of steel and/or copper, and the window is preferably made of CaF2.

Abstract: The present invention reduces multimoding of light generated by lasers. An asymmetric dispersion enhancer is included in a laser cavity to increase the asymmetric dispersion of the light amplified in the cavity. As a result, the side modes of the light passing through the cavity are asymmetrically disposed about the fundamental mode and, therefore, are amplified less in the cavity. Consequently, multimoding of the light is better suppressed.

Abstract: A gas discharge laser capable of operating at pulse rates in the range of 4,000 Hz to 6,000 Hz at pulse energies in the range of 5 mJ to 10 mJ or greater. Important improvements over prior art designs include: (1) a squirrel cage type fan for producing gas velocities through the discharge region of more than 67 m/s and capable of continuous trouble-free operation for several months, (2) a liquid cooled drive motor having a low loss sealing member separating the motor rotor from the motor starter and protecting the motor from the laser gas and a breach detection device for detecting any breach of the sealing member, (3) a heat exchanger system capable of removing in excess of 16 kw of heat energy from the laser gas and (4) a pulse power system capable of providing precisely controlled electrical pulses to the electrodes needed to produce laser pulses at the desired pulse energies in the range of 5 mJ to 10 mJ or greater at pulse repetition rates in the range of 4,000 Hz to 6,000 Hz or greater.

Abstract: An F2-excimer laser has multiple closely-spaced spectral lines of interest around 157 nm, and one of the lines is selected by wavelength selection optics. The wavelength selection optics of a first preferred embodiment include a birefringent Brewster window enclosing the laser gas volume of the discharge chamber. The window preferably comprises MgF2 and is located at one end of the discharge chamber. One line is selected of the two when the optical thickness of the window is selected in coordination with rotatably adjustable, orthogonal refractive indices of the window. The transmissivity of the window is dependent on the orthogonal refractive indices and the optical thickness of the window. The wavelength selection optics of a second preferred embodiment include are at least partially within the laser active volume. In this way, line selection is performed in a manner which optimizes the combination of optical and discharge efficiency, resonator size and cost.