Abstract: An excimer or molecular fluorine laser system includes a discharge chamber containing a gas mixture, multiple electrodes connected to a power supply circuit for energizing the gas mixture, a resonator for generating a laser beam, a processor, and means for monitoring an amplified spontaneous emission (ASE) signal of the laser, such as preferably an ASE detector. The processor receives a signal from the preferred ASE detector indicative of the ASE signal of the laser. Based on the signal from the ASE detector, the processor determines whether to initiate a responsive action for adjusting a parameter of the laser system.

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: 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: In a preionization discharge circuit 10, when a switch SW14 is turned on, an electric current i10 from a constant current source 13 flows through a loop of a coil L12, en electrode 11A and the switch SW14. When it is assumed that an inductance of the coil L12 is L (H) and the current i10 flowing through the coil L12 is I (A), energy EL of (1/2)·L·I{circumflex over ( )}2 is accumulated in the coil 12. Meanwhile, in a preionization discharge control section 40, a preionization discharge timing signal (namely, a corona emission timing signal) Ydt is output to the switch SW14 after lapse of a time ty (=Tds−tyd) after a pulse oscillation synchronizing signal TRL is received so that preionization discharge is caused earlier by a preset time tyd than the preionization discharge timing signal Ydt.

Abstract: An apparatus for frequency conversion of a laser (1) in which one or more non-linear crystals (5, 6) are arranged in the laser beam (3), and the necessary power density is produced by an arrangement of a dedicated focussing lens (4), in the region of the focal point (14), with a collimator, which minimizes the divergence of the laser beam (3), an optical corrector, which shapes the cross section of the laser beam (3). A single focussing lens (4) is provided behind which a corrective lens (7) is arranged at an angle to the optical axis and at a distance which corresponds roughly to the sum of both focal lengths such that the focussing lens (4) and the corrective lens (7) form the collimator and the corrective lens (7) also functions as a corrector. In this way a laser is produced which is characterized by small size and a simple and economical construction.

Abstract: A beam parameter monitoring unit is provided for use with a F2 laser system including means for filtering the red light from the VUV light of a beam portion split off from the mainbeam of the F2 laser before the beam portion reaches a detector. The filtering means includes a mirror that is highly reflective of VUV light (“VUV HR mirror”), particularly around 157 nm, and transparent to red light. The VUV HR mirror reflects the VUV light to a detector such that the properties and parameters of the main beam can be monitored, adjusted, controlled and/or stabilized. The VUV HR mirror is preferably surrounded by a shield for absorbing the red light transmitted through or around the VUV HR mirror. Also preferably, an aperture is provided that is just wide enough to permit the VUV radiation to substantially pass through, and to block the outer portions of the incident beam portion including substantially only red light.

Abstract: A method is provided for determining the status of a gas mixture of a laser system including a gas discharge laser which generates an output beam and has a discharge chamber containing a gas mixture within which energy is supplied to the gas mixture by a power supply via application of a driving voltage to a discharge circuit. A master data set of an output parameter such as any of output beam energy, bandwidth, spectrum width, long axial beam profile, short axial beam profile, beam divergence, energy stability, energy efficiency, width of the discharge, temporal beam coherence, spatial beam coherence, spatial pulse width, amplified spontaneous emission and temporal pulse width versus an input parameter such as driving voltage is generated corresponding to an optimal gas mixture status, preferably after a new fill and typically at the factory, and alternatively following a new fill at the fab.

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 laser system includes a travelling-wave active laser-resonator arranged for generating laser-radiation having a first wavelength and arranged such that the first-wavelength radiation circulates in only one direction therein. An optically-nonlinear element is positioned in the travelling-wave laser-resonator such that the first-wavelength radiation circulates therethrough. Radiation having a second-wavelength is injected into the optically-nonlinear crystal such that the first-wavelength radiation and second-wavelength radiation mix therein, thereby generating radiation having the sum-frequency of the first and second-wavelength radiations. The sum-frequency radiation from the optically-nonlinear element is delivered from the laser system as output-radiation. In one example, the travelling-wave resonator has a YVO4 gain medium generating radiation having a wavelength of about 1064 nm. The optically-nonlinear crystal is a CLBO crystal.

Abstract: Techniques for stabilizing a laser (110) at a selectable frequency include splitting an output beam from an electrically adjustable laser into a first beam (369) and a second beam (361). The second beam is transmitted through a modulator (112). Then the second beam is transmitted through a spectral hole burning material (310) onto a detector (120). The laser is electronically adjusted in response to a detector output from the detector which senses the changes in the modulated second beam after it passes through the spectral hole burning material.

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. One of the resonator reflectors is an output coupling interferometer including a pair of opposing reflecting surfaces tuned to produce a reflectivity maximum at a selected wavelength for narrowing a linewidth of the output laser beam. One of the pair of opposing reflecting surfaces is 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 outer portions of the reflectivity maximum to reduce spectral purity.

Abstract: An improved method and apparatus for mode-locking a fiber laser at a pre-selected frequency wherein a doped fiber segment contains a narrowband FBG and an electro-optically tuned FBG, thereby making obsolete the need for an EOM to modulate the laser's wavelength. The present invention also provides a method and apparatus for mode-locking a fiber laser at a variable frequencies wherein a doped fiber segment contains two electro-optically tuned FBG's. The electro-optically tuned FBG may be fabricated by a thermal poling process.

Abstract: The amount of pre-ionization by the pre-ionization electrode provided on the gas outflow side of the main discharge space, out of at least one pair of pre-ionization electrodes, is adjusted so as to attain the desired beam profile. As a result, the pre-ionization intensity of the laser gas remaining on the gas outflow side of the main discharge space is made lower than the pre-ionization intensity of the laser gas flowing into the main discharge space. In other words, the intensity of the laser light on the gas outflow side of the main discharge space is made weaker than the intensity of the laser light in the center of the main discharge space. Accordingly, the location of the maximum light intensity of the beam profile does not deviate from the center of the discharge width.

Abstract: A high power, diode pumped laser has a Nd:YVO4 gain media. Scaling to higher powers is achieved with the use of a low doped gain media, increasing the length of the gain media as well as increasing the pump volume. Passive cooling is extended to output powers of 10 W or greater.

Abstract: A method and apparatus is provided for stabilizing output beam parameters of a gas discharge laser by maintaining a constituent gas of the laser gas mixture at a predetermined partial pressure using a gas supply unit and a processor. The constituent gas of the laser gas mixture is provided at an initial partial pressure and the constituent gas is subject to depletion within the laser discharge chamber. Injections of the constituent gas are performed each to increase the partial pressure by a selected amount in the discharge chamber preferably less than 0.2 mbar per injection. A number of successive injections is performed at selected intervals to maintain the constituent gas substantially at the initial partial pressure for maintaining stable output beam parameters. The amount per injection and/or the interval between injections may be varied based on the measured value of the driving voltage and/or a calculated amount of the constituent gas in the discharge chamber.

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: A multiple stage laser system that produces coherent light in the ultraviolet range using phase conjugated Stimulated Raman Scattering and harmonic generation. The system uses a pump laser producing an input beam that is frequency shifted via phase conjugating Stimulated Raman Scattering. The Raman shifted beam is passed through a harmonic generation stage that produces the desired output beam by generating the required harmonic of the Raman shifted beam.

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: Method of processing, e.g., laser annealing, objects such as semiconductor devices with pulsed lasers with high production yield and high reproducibility so as to obtain good characteristics stably. The pulse width of the irradiated pulse beam is set to more than 30 nsec to stabilize the processing. To achieve a pulse width exceeding 30 nsec, plural lasers are connected in series or in parallel and excited successively.

Abstract: The present invention provides a reliable modular production quality excimer laser capable of producing 10 mJ laser pulses in the range of 1000 Hz to 2000 Hz or greater. Replaceable modules include a laser chamber; a pulse power system comprised of three modules; an optical resonator comprised of a line narrowing module and an output coupler module; a wavemeter module, an electrical control module, a cooling water module and a gas control module. Important improvements have been provided in the pulse power unit to produce faster rise time and improved pulse energy control. These improvements include an increased capacity high voltage power supply with a voltage bleed-down circuit for precise voltage trimming, an improved communication module that generates a high voltage pulse from the capacitors charged by the high voltage power supply and amplifies the pulse voltage 23 times with a very fast voltage transformer having a secondary winding consisting of a single four-segment stainless steel rod.