842 results about "Lasing wavelength" patented technology

Apparatus for dynamic surface annealing of a semiconductor wafer includes a source of laser radiation emitting at a laser wavelength and comprising an array of lasers arranged in rows and columns, the optical power of each the laser being individual adjustable and optics for focusing the radiation from the array of lasers into a narrow line beam in a workpiece plane corresponding to a workpiece surface, whereby the optics images respective columns of the laser array onto respective sections of the narrow line beam. A pyrometer sensor is provided that is sensitive to a pyrometer wavelength. An optical element in an optical path of the optics is tuned to divert radiation emanating from the workpiece plane to the pyrometry sensor. As a result, the optics images each of the respective section of the narrow line beam onto a corresponding portion of the pyrometer sensor. The apparatus further includes a controller responsive to the pyrometry sensor and coupled to adjust individual optical outputs of respective columns of the laser array in accordance with outputs of corresponding portions of the pyrometry sensor.

The present invention is an alternative Fourier domain optical coherence system (FD-OCT) and its associated method. The system comprises a swept multi-wavelength laser, an optical interferometer and a multi-channel receiver. By employing a multi-wavelength laser, the sweeping range for each lasing wavelength is substantially reduced as compared to a pure swept single wavelength laser that needs to cover the same overall spectral range. The overall spectral interferogram is divided over the individual channels of the multi-channel receiver and can be re-constructed through processing of the data from each channel detector. In addition to a substantial increase in the speed of each axial scan, the cost of invented FD-OCT system can also be substantially less than that of a pure swept source OCT or a pure spectral domain OCT system.

The present invention is an alternative Fourier domain optical coherence system (FD-OCT) and its associated method. The system comprises a swept multi-wavelength laser, an optical interferometer and a multi-channel receiver. By employing a multi-wavelength laser, the sweeping range for each lasing wavelength is substantially reduced as compared to a pure swept single wavelength laser that needs to cover the same overall spectral range. The overall spectral interferogram is divided over the individual channels of the multi-channel receiver and can be re-constructed through processing of the data from each channel detector. In addition to a substantial increase in the speed of each axial scan, the cost of invented FD-OCT system can also be substantially less than that of a pure swept source OCT or a pure spectral domain OCT system.

An organic or organoelement, linear or branched, monomeric or polymeric composition of matter having a Raman-active component in the form of particles. The particles having a maximum dimension of 50 mum. The Raman-active compound is applied to a substrate. When the Raman-active compound is exposed to a laser light wavelength which is batochromically well beyond a spectral region of maximum absorbance of said Raman-active compound, Raman scattering can be detected.

A method for machining a transparent material by the non-linear absorption of pulsed laser radiation, in the region of a laser focus, includes the following steps: a laser wavelength of between 300 and 1000 μm is selected; and laser impulses having a temporally flat beam profile are applied. The method is characterized in that the irradiation intensity is selected from an interval pre-determined for the material to be machined, in which plasma is formed without plasma luminescence. An apparatus for laser treating a transparent material includes structure to set an irradiance and inspect the treatment as being within a defined interval.

An organic or organoelement, linear or branched, monomeric or polymeric composition of matter having a Raman-active component in the form of particles. The particles having a maximum dimension of 50 mum. The Raman-active compound is applied to a substrate. When the Raman-active compound is exposed to a laser light wavelength which is batochromically well beyond a spectral region of maximum absorbance of said Raman-active compound, Raman scattering can be detected.

A laser scanning microscope produces molecular excitation in a target material by simultaneous absorption of three or more photons to thereby provide intrinsic three-dimensional resolution. Fluorophores having single photon absorption in the short (ultraviolet or visible) wavelength range are excited by a beam of strongly focused subpicosecond pulses of laser light of relatively long (red or infrared) wavelength range. The fluorophores absorb at about one third, one fourth or even smaller fraction of the laser wavelength to produce fluorescent images of living cells and other microscopic objects. The fluorescent emission from the fluorophores increases cubicly, quarticly or even higher power law with the excitation intensity so that by focusing the laser light, fluorescence as well as photobleaching are confined to the vicinity of the focal plane. This feature provides depth of field resolution comparable to that produced by confocal laser scanning microscopes, and in addition reduces photobleaching and phototoxicity. Scanning of the laser beam by a laser scanning microscope, allows construction of images by collecting multi-photon excited fluorescence from each point in the scanned object while still satisfying the requirement for very high excitation intensity obtained by focusing the laser beam and by pulse time compressing the beam. The focused pulses also provide three-dimensional spatially resolved photochemistry which is particularly useful in photolytic release of caged effector molecules, marking a recording medium or in laser ablation or microsurgery. This invention refers explicitly to extensions of two-photon excitation where more than two photons are absorbed per excitation in this nonlinear microscopy.

The present invention includes novel techniques, apparatus, and systems for optical WDM communications. Various wavelocker apparatus and methods are disclosed that measure the frequency offsets between signal lasers and reference lasers. The measured offsets are used to adjust the signal laser frequencies to meet their target frequencies. The absolute accuracy of the reference laser frequency is improved by measuring the absorption of the reference laser by a gas cell with known fixed absorption lines versus the reference laser frequency. Apparatus and methods are disclosed to cover scenarios in which the reference laser polarization is aligned with the signal lasers, as well as those in which the reference laser polarization is not aligned with the signal lasers. The wavelocker apparatus may or may not be located at the same network site as the signal lasers.

The present invention provides a photoacoustic spectrometer that is field portable and capable of speciating complex organic molecules in the gas phase. The spectrometer has a tunable light source that has the ability to resolve the fine structure of these molecules over a large wavelength range. The inventive light source includes an optical parametric oscillator (OPO) having combined fine and coarse tuning. By pumping the OPO with the output from a doped-fiber optical amplifier pumped by a diode seed laser, the inventive spectrometer is able to speciate mixtures having parts per billion of organic compounds, with a light source that has a high efficiency and small size, allowing for portability. In an alternative embodiment, the spectrometer is scanned by controlling the laser wavelength, thus resulting in an even more compact and efficient design.

The present invention is a tunable semiconductor laser for swept source optical coherence tomography, comprising a semiconductor substrate; a waveguide on top of said substrate with multiple sections of different band gap engineered multiple quantum wells (MQWs); a multiple of distributed feedback (DFB) gratings corresponding to each said band gap engineered MWQs, each DFB having a different Bragg grating period; and anti-reflection (AR) coating deposited on at least the laser emission facet of the laser to suppress the resonance of Fabry-Perot cavity modes. Each DFB MQWs section can be activated and tuned to lase across a fraction of the overall bandwidth as is achievable for a single DFB laser and all sections can be sequentially activated and tuned so as to collectively cover a broad bandwidth, or simultaneously activated and tuned to enable a tunable multi-wavelength laser. The laser hence can emit either a single lasing wavelength or a multiple of lasing wavelengths and is very suitable for swept-source OCT applications.

A laser amplifier includes a laser active slab with a source of pump power to amplify an input laser beam, the laser active slab including a block of laser active material having opposed lateral faces defining a wedge lateral dihedral angle, opposed longitudinal faces, and opposed parallel transverse faces, the wedge lateral dihedral angle specified to minimize parasitic amplified spontaneous emission. The source of pump power may be one or more laser diode bars and microlenses producing a gain sheet in the laser active slab. The lateral faces may include optical coatings highly transmitting at a wavelength of the pump power and highly reflecting at a lasing wavelength to provide a folded path for the input laser beam though the gain sheet. The laser amplifier may optionally include one or more external mirrors highly reflecting at the lasing wavelength positioned and oriented to provide one or more additional zig-zag passes through the gain sheet for the input laser beam and to provide a multi-pass-amplified laser beam.

A novel optical ruler based on ultrahigh-resolution colocalization of single fluorescent probes is described. Two unique families of fluorophores are used, namely energy-transfer fluorescent beads and semiconductor nanocrystal (NC) quantum dots, that can be excited by a single laser wavelength but emit at different wavelengths. A novel multicolor sample-scanning confocal microscope was constructed which allows one to image each fluorescent light emitter, free of chromatic aberrations, by scanning the sample with nanometer scale steps using a piezo-scanner. The resulting spots are accurately localized by fitting them to the known shape of the excitation point-spread-function of the microscope.

A passively mode-locked solid-state laser is designed to emit a continuous-wave train (51, 52) of electromagnetic-radiation pulses, the fundamental repetition rate of the emitted pulses exceeding 1 GHz, without Q-switching instabilities. The laser includes an optical resonator (3.1), a solid-state laser gain element (2) placed inside the optical resonator (3.1), a device (1) for exciting said laser gain element (2) to emit electromagnetic radiation having the effective wavelength, and a device (4) for passive mode locking including a saturable absorber. The laser gain element (2) is a laser material with a stimulated emission cross section exceeding 0.8×10−18 cm2 at the effective wavelength, and is made of Nd:vanadate. The saturable absorber (4) is preferably a semiconductor saturable absorber mirror (SESAM) device. Even higher repetition rates are achieved by operating the laser in the soliton regime. For use in fiber-optical telecommunication, the laser wavelength is preferably shifted to 1.5 μm by use of an optical parametric oscillator. The laser is simple, robust, compact, efficient, and low-cost. It generates a relatively large average power of 100 mW and higher, which is useful for a number of optical probing and detection applications, in a beam (51, 52) that is substantially a fundamental spatial mode.

The invention discloses a fire scene multi-parameter laser wavelength modulation spectrum detection method and a device thereof, wherein, fire smoke products are treated through a smoke pre-treatment device and then pumped into a white cell through an air extracting pump; a multi-channel laser controller scans and modulates the wavelengths of a plurality of DFB lasers according to the time-sharing and multiplexing working mode, and all waves of laser share an optical fiber and are outputted sequentially through a wave combiner, then are aligned by a fiber collimator and sent to the white cell to detect the fire smoke products; a photoelectric detector converts light intensity signals of laser repeatedly reflected and absorbed by the white cell into electrical signals which are sent to two phase-locking magnifier modules for frequency selecting magnification so as to obtain a fundamental frequency component and a second harmonic component; a multi-channel data acquisition card converts output voltage signals of the phase-locking magnifiers into digital signals which are sent to a micro-computer for real-time data processing, so that the fire scene multi-parameter information containing the oxygen concentration of the fire scene, concentrations of various toxic gases and smoke concentration is obtained. The detection method and device can realize real-time on-line monitoring to fire scene multi-parameters, and have the advantages of being real-time, multi-component and highly sensitive, good selectivity of gas, high reliability and strong environmental disturbance resistance ability.

The invention relates to a laser-based light source comprising a laser device (1) adapted for generating laser light of a predetermined laser wavelength and emitting this laser light as a laser beam; a light-conversion device (2) for converting at least part of the laser light into converted light; a laser-output sensor (7) for determining a laser-output signal proportional to the output of laser light emitted by the laser device (1); a converted-light sensor (6) for determining a converted-light signal proportional to the output of converted light emitted by the light-conversion device (7); and a controller (9) which is adapted for receiving the laser-output signal and the converted-light signal, for determining a safe-to-operate parameter, based on the laser-output signal and the converted-light signal, and for controlling the operation of the laser-based light source, based on a comparison of the safe-to-operate parameter with a at least one predefined threshold. In this way, a laser-based light source is proposed which enables reliable eye-safety in an easy way.

One embodiment of the present invention provides a system that facilitates adjusting the wavelengths of lasers via temperature control. This system includes a chip with an active face upon which active circuitry and signal pads reside. A thermal-control mechanism provides localized thermal control of two lasers mounted upon the active face of the chip. By individually controlling the temperature of the lasers, the thermal-control mechanism controls the wavelengths emitted by each respective laser. By creating a temperature gradient that causes a temperature difference between two or more lasers, the system can cause the lasers to emit different wavelengths.

The method and system operate to calibrate a transmission laser of the dense wavelength division multiplexer (DWDM) and to lock the laser to a selected transmission wavelength. In one example, the transmission laser is a widely tunable laser (WTL) to be tuned to one of a set of International Telecommunications Union (ITU) transmission grid lines for transmission through an optic fiber. To lock the WTL to an ITU grid line, a portion of the output beam from the WTL is routed through the etalon to split the beam into a set of transmission lines for detection by an etalon fringe detector. Another portion of the beam is routed directly to a laser wavelength detector. A wavelength-locking controller compares signals from the two detectors and adjusts the temperature of the etalon to align the wavelength of one of the transmission lines of the etalon with the wavelength of the output beam, then controls the WTL in a feedback loop to lock the laser to the etalon line. The wavelength-locking controller thereafter monitors the temperature of the etalon and keeps the temperature constant to prevent any wavelength drift in the etalon. In one example, the optical components are aligned so that laser wavelength detector receives a portion of the laser beam directly from the laser so that phase characteristics of the laser beam are not affected by an intervening beamsplitter thereby permitting improved wavelength locking. In another embodiment, an etalon chirp filter is provided for reducing or eliminating optical frequency chirp, regardless of the particular ITU channel being used for transmission.

An object of disclosed technology is to control lasing wavelengths so that a wavelength shift does not occurs. Another object is to permit wavelengths of a light source for wavelength division multiplexing optical-fiber communication system to be variable in response to an ITU-TS grid. A means for achieving the objects is as follows: locating an etalon in a light path of diode laser light, which is a parallel plane wave changed by a collimator lens; generating a wavelength error signal from a difference between both of divided pieces of light from transmitted light or reflected light; and locking a wavelength of a diode laser device according to the wavelength error signal.

We describe a holographic image projector, comprising: a laser light source to provide light at a laser wavelength; a first spatial light modulator (SLM) to display a hologram, wherein said first SLM is illuminated by said laser light source; intermediate image optics to provide a first intermediate real image plane at which a real image produced by said hologram displayed on said first SLM is formed; a wavelength-conversion material located at said first intermediate real image plane to convert said laser wavelength to at least a first output wavelength different to said laser wavelength; and second optics to project light from said real image at said output wavelength to provide a displayed image.

An external cavity laser apparatus and method wherein wavelength or channel selection is carried independently from adjustment of external cavity optical path length. The apparatus comprises a wavelength or channel selector tuner and an external cavity tuner, wherein the wavelength tuner is uncoupled from the external cavity tuner. The tuning mechanisms for wavelength selection and cavity optical path length are configured to operate independently or orthogonally with respect to each other. The wavelength tuner may operate according to a first, channel selection signal, while the external cavity tuner operates according to a second, external cavity adjustment signal. The wavelength tuner and external cavity tuner may operate under the control of the same, or of separate controllers. The channel selection signal may be derived from a look-up table of adjustment parameter data accessed by a controller, and the external cavity adjustment signal may be derived from an error signal from a detector configured to measure external cavity loss.

The present invention discloses a laser amplifier with high gain and low thermally induced optical aberrations on the amplified laser beam. The amplifier designs allow simple multipass configurations to optimally extract the gain and reduce thermally induced index of refraction aberrations, making it possible to obtain an amplified laser beam of high quality combined with very high overall gains comparable to those achievable with expensive regenerative amplifiers. The amplifier includes a thin active laser solid to create the population inversion and associated heat generation within the thin laser active solid possible for the desired gain value. The system includes a cooling device in thermal contact with the thin active laser solid to provide good heat transport and high reflectivity coatings at the wavelengths of the pump and laser wavelengths. The pump light sources are laser diodes tuned to the maximum absorption of the laser active material. The amplifier also includes an optical system to transport the pump light to the laser active solid in such a way as to further confine the absorption of light along the two orthogonal directions in the plane of the laser active solid in order to get high population inversion and consequently high gains possible.

Presbyopia is treated by a method which uses various lasers to remove a portion of the scleral tissue and increase the accommodation of the presbyopic patient's eye. Stable accommodation is achieved by the filling of the sub-conjunctival tissue to the laser-ablated scleral areas. The proposed laser wavelength ranges from ultraviolet to infrared of (0.15-0.36) microns, (0.5-1.4) microns and (0.9-10.6) microns. Both scanning and fiber delivered systems are proposed.

Presbyopia is treated by a method which uses various lasers to remove a portion of the scleral tissue and increase the accommodation of the presbyopic patient's eye. Stable accommodation is achieved by the filling of the sub-conjunctival tissue to the laser-ablated scleral areas. The proposed laser wavelength ranges from ultraviolet to infrared of (0.15-0.36) microns, (0.5-1.4) microns and (0.9-10.6) microns. Both scanning and fiber delivered systems are proposed.

The present invention discloses a fiber Bragg grating sensor system. The system according to the present invention comprises a wavelength tunable laser; a coupler for splitting output light from the wavelength tunable laser into two directions; a reference wavelength generating unit for receiving one directional output light from the coupler and for generating reference wave-lengths and an absolute reference wavelength in order to measure real-time wavelengths of the wavelength tunable laser; a fiber Bragg grating array for receiving the other directional output light from the coupler and for reflecting lights at each of the wave-lengths of the grating therein; a fiber grating wavelength sensing unit for measuring the time when each of the reflected lights from the fiber Bragg grating array is detected; a signal processing unit for figuring wavelength variation information with the use of the measured signals from the reference wavelength generating unit and for obtaining each of wavelengths of the detected lights from the fiber grating wavelength sensing unit; and a laser wavelength control feedback unit for applying AC voltage and DC voltage to the wavelength tunable filter in the wavelength tunable laser. Also, polarization dependency in the sensor system can be removed further installing a depolarizer or a polarization scrambler at the output end of the wavelength tunable laser. By applying the present invention, measurement accuracy of the grating sensor system 20 can be improved due to enhanced wavelength stability and suppression of polarization dependency. Therefore, the fiber Bragg grating sensor system based on the present invention would replace conventional structure / construction diagnosis systems.

Vertical cavity optical devices, and a method of manufacturing therefor, are provided where the method includes partially forming a first vertical cavity optical device on a wafer, adjusting the lasing wavelength of the first vertical cavity optical device, and fixing the lasing wavelength of the first vertical cavity optical device to complete the forming thereof.

High performance optical edge and laser-line filters and methods of making the same are disclosed. The optical edge filters have an edge steepness greater than about 0.8% as measured by dividing (a) the edge width from the 50% transmission wavelength to the optical density 6 (“OD6”) wavelength by (b) the 50% transmission wavelength. The optical edge filters also have an average transmission above about 95%. The laser-line filters have an extremely high transmission in the passband (greater than 90%), an extremely narrow transmission bandwidth, and achieve blocking with an optical density (OD) greater than 5 at wavelengths that differ from the laser wavelength by less than 1% of the laser wavelength. The methods for making such filters accurately determine when deposition of each layer of the filter should terminate.

A method of exciting an optical transition in a narrowly limited area of a material comprising the steps of focusing an excitation light beam whose wavelength is tuned to the optical transition to be excited into a focal area extending beyond a focal point; splitting up a de-excitation light beam which is at least somehow influencing the optical transition into at least two partial beams; focusing the at least two partial beams of the de-excitation light beam out of different directions onto the focal point to form a spatially extending interference pattern in the focal area; adjusting a relative phase of the at least two partial beams of the de-excitation light beam so that the interference pattern has an intensity minimum at the focal point and a plurality of intensity maxima on different sides of the focal point; and aberrating the wave fronts of the at least two partial beams of the de-excitation light beam so that the intensity maxima of the interference pattern on different sides of the focal point are spatially expanded without eliminating the intensity minimum at the focal point.

Presbyopia is treated by a method which uses various lasers to remove a portion of the scleral tissue and increase the accommodation of the presbyopic patient's eye By changing the laser power density, fluency or spot size, a single laser device having dual-function of ablation and coagulation is proposed for minimum bleeding. Fiber-bundle coupled to a single fiber is presented to increase the power density of the laser for efficient tissue ablation New mechanisms of lens curvature change and lens anterior shift are proposed for the total accommodation. The preferred laser wavelength ranges from ultraviolet to infrared including (0.15-0.36) microns, (0.9-1.6) microns, (1.8-2.2) microns and (2.8-3.2) microns Both scanning and fiber delivered systems are proposed.

The invention provides an external cavity semiconductor laser with multi-wavelength combination. The external cavity semiconductor laser comprises a plurality of semiconductor laser units, alignment optical lenses arranged in order on output optical paths of the semiconductor laser units, dispersion optical elements, and partial reflectors. The plurality of semiconductor laser units are in a array arrangement, and a plurality of resonant external cavities are formed by each semiconductor laser unit, the dispersion optical element, and the partial reflector. In the formed structure of the external cavity, the each semiconductor laser unit automatically adjusts the output wave of the semiconductor laser unit, so that a multi-wavelength light beam finally output by the partial reflector is a parallel and single laser with multi wavelengths. According to the external cavity semiconductor laser with multi-wavelength combination provided in the invention, an effective multi-wavelength laser light source is provided; an actual lasing wavelength of each die are stabilized automatically to be a wavelength that is needed to make the system work cooperatively.