893 results about "Nonlinear crystals" patented technology

A laser system capable of efficient production of high energy sub-nanosecond pulses in the 2-15 μm spectral region is disclosed. Diode pumped solid state lasers are used as pump sources. The system design is simple, reliable and compact allowing for easy integration. The laser system includes a combination of compact solid-state ˜1 micron laser sources, producing high power picosecond pulses, with optical parametric amplification and a quasi-continuous wave laser for seeding the amplification process that enables the efficient conversion of the high power ˜1 micron laser radiation to tuneable mid-infrared sub-ns pulses. New parametric processes are presented for achieving high gains in bulk nonlinear crystals. Furthermore, a method of exceeding the fundamental conversion efficiency limit of direct three wave mixing is presented. The compact and robust nature of this novel laser system opens up the use of high power and high peak power mid-infrared laser pulses to a wide variety of important medical and dental applications.

A surgical technique for removing corneal tissue with scanned infrared radiation is disclosed which utilizes short mid-infrared laser pulses to provide a tissue removal mechanism based on photospallation. Photospallation is a photomechanical ablation mechanism which results from the absorption of incident radiation by the corneal tissue. Since photospallation is a mechanical ablation process, very little heat is generated in the unablated adjacent tissue. The disclosed surgical system includes a scanning beam delivery system which allows uniform irradiation of the treatment region and utilizes low energy outputs to achieve controlled tissue removal. A real-time servo-controlled dynamic eye tracker, based on a multiple-detector arrangement, is also disclosed which senses the motion of the eye and provides signals that are proportional to the errors in the lateral alignment of the eye relative to the axis of the laser beam. Temporal and frequency discrimination are preferably utilized to distinguish the tracking illumination from the ambient illumination and the surgical laser beam. A laser parametric generator for surgical applications is disclosed which utilizes short-pulse, mid-infrared radiation. The mid-infrared radiation may be produced by a pump laser source, such as a neodymium-doped laser, which is parametrically down converted in a suitable nonlinear crystal to the desired mid-infrared range. The short pulses reduce unwanted thermal effects and changes in adjacent tissue to potentially submicron-levels. The parametrically converted radiation source preferably produces pulse durations shorter than 25 ns at or near 3.0 microns but preferably close to the water absorption maximum associated with the tissue. The down-conversion to the desired mid-infrared wavelength is preferably produced by a nonlinear crystal such as KTP or its isomorphs. In one embodiment, a non-critically phased-matched crystal is utilized to shift the wavelength from a near-infrared laser source emitting at or around 880 to 900 nm to the desired 2.9-3.0 microns wavelength range. A fiber, fiber bundle or another waveguide means utilized to separate the pump laser from the optical parametric oscillation (OPO) cavity is also included as part of the invention.

Surgical method and apparatus for presbyopia correction and glaucoma by laser removal a portion of the sclera and / or ciliary tissue are disclosed. The disclosed preferred embodiments of the system consists of a beam spot controller, an articulated arm and an attached end-piece. The basic laser beam includes UV laser having wavelength ranges of (0.19-0.36) microns, generated from UV excimer lasers of ArF, XeCl or solid state lasers of Nd:YLF, Nd:YAG, Ti:sapphire with harmonic generation using nonlinear crystals. Presbyopia is treated by ablation of the treated surface tissue in predetermined patterns outside the limbus to increase the accommodation of the eye. Glaucoma is treated by decreasing of intra ocular pressure of the laser surgery.

An optical parametric oscillator (OPO) is described that efficiently converts a near-infrared laser beam to tunable mid-infrared wavelength output. In some embodiments, the OPO includes an optical resonator containing a nonlinear crystal, such as periodically-poled lithium niobate. The OPO is pumped by a continuous-wave fiber-laser source having a low-power oscillator and a high-power amplifier, or using just a power oscillator). The fiber oscillator produces a single-frequency output defined by a distributed-feedback (DFB) structure of the fiber. The DFB-fiber-laser output is amplified to a pump level consistent with exceeding an oscillation threshold in the OPO in which only one of two generated waves (“signal” and “idler”) is resonant within the optical cavity. This pump source provides the capability to tune the DFB fiber laser by straining the fiber (using an attached piezoelectric element or by other means) that allows the OPO to be continuously tuned over substantial ranges, enabling rapid, wide continuous tuning of the OPO output frequency or frequencies.

Method and systems for eye surgery for the treatment of presbyopia, ocular hypertension and glaucoma and other soft tissue surgeries are disclosed. System design parameters of lasing crystals (Nd:YAG, Nd:YLF, Er:YAG and Er:YSGG), nonlinear crystals (KTP, BBO, LBO), laser cavity configuration and energy delivery means are disclosed for diode-laser-pumped lasers with output wavelength at UV (263 or 266 nm), green (527 or 523 nm), and mid-IR (2.78 or 2.94 microns). Dual function of ablation and coagulation is proposed by a mode control means. The preferred diode-laser includes a wavelength at about 0.75 to 0.98 microns with power about 15 to 40 W and used in a side-pumping configuration to generate UV or IR having an energy per pulse about 3 to 30 mJ, power of about 0.1 to 1.5 W and operated at free running mode (IR laser) or pulsed mode (UV laser).

A laser device comprises a non-collinear optical parametric generator (OPG) and a pump wave source (4). The OFG comprises a non-linear crystal (1) fixedly mounted within the generator wherein the relative orientations of the pump wave (3) and each generated wave (5) to an optic axis (2) of the non-linear crystal (1) are substantially such that a point of inflexion is produced in a tuning curve of wavelength versus pump wave orientation of one of the generated waves, such that a broadband spectral output is obtained. This device has many applications including an amplifier for an input seed wave in which the crystal dose not have to be rotated to match the wavelength of the seed wave; or as part of a continuously tuneable narrowband source.

A method for operating an extracavity frequency-converted solid-state laser for performing a laser processing operation is disclosed. The laser has a laser-resonator including an optically-pumped gain-medium. The resonator is configured to compensate for a predetermined range of thermal lensing in the gain-medium. An optically-nonlinear crystal located outside the resonator converts fundamental laser radiation delivered by the resonator into frequency converted radiation. The laser processing operation is performed by a train of pulses of the frequency-converted radiation having sufficient power to perform the processing operation. The power of frequency-converted radiation is dependent on delivery parameters of the laser radiation from the laser-resonator. The laser is operated in a manner which provides that the resonator delivers effectively the same average power of fundamental laser radiation before and during the laser processing operation. This provides that thermal-lensing in the gain-medium is within the predetermined range before and during a laser processing operation. Delivery parameters of the laser radiation before and during the processing operation are varied such that power of frequency-converted radiation generated before the processing operating is insufficient to perform a laser processing operation.

Several methods are disclosed for the generation of coherent short-wavelength electromagnetic radiation through optical nonlinear frequency mixing means. The invention involves several stages of efficient nonlinear frequency conversion to shift the output of high-power infra-red fiber-lasers into the vacuum ultraviolet (VUV). The described laser source architecture is designed around non-critically phase-matched (NCPM) sum-frequency mixing (SFM) interactions in the nonlinear crystal CLBO. The NCPM interaction is an optimum condition for bulk frequency conversion of cw radiation because it allows tight focusing of the input laser radiation without Poynting vector walk-off, thereby increasing the non-linear drive significantly. The sub-200-nm output wave is generated from SFM of a long-wave IR laser field and a short-wave UV laser field. The long-wave laser beam may be derived directly from a rare-earth-doped fiber laser, whereas the short-wavelength UV beam is provided as the fourth frequency harmonic of a second rare-earth-doped fiber laser system.

A method of intracavity frequency conversion in a CW laser includes causing fundamental radiation to circulate in a laser resonator. The fundamental radiation makes a first pass through an optically nonlinear crystal where a fraction of the fundamental radiation generates second-harmonic radiation in a forward pass through the crystal. The residual fundamental radiation and the second-harmonic radiation are then sum-frequency mixed in forward and reverse passes through an optically nonlinear crystal such that a fraction of each is converted to third-harmonic radiation. The residual second-harmonic radiation and fundamental radiation from the sum-frequency mixing then make a reverse pass through the second-harmonic generating crystal where the second-harmonic radiation is converted back to fundamental radiation. The third harmonic radiation can be delivered from the resonator as output radiation, or can be used to pump another optically nonlinear crystal in an optical parametric oscillator. Second-harmonic radiation can also be used to pump an optical parametric oscillator.

A compact and efficient ultraviolet laser source based on a optically-pumped solid-state or fiber laser that produces near-infrared output light suitable for nonlinear frequency conversion. The infrared laser output is frequency tripled or quadrupled to produce light in the ultraviolet wavelength range (200 nm to 400 nm). The novel technology is the use of highly efficient periodically poled nonlinear crystals, such as stoichiometric and MgO-doped lithium tantalate and lithium niobate. As opposed to conventional frequency-converted UV laser sources, which have high power consumption, high cost, and low efficiency, the laser sources of this invention utilize high efficiency nonlinear conversion provided by periodically poled materials and allow lower-cost architectures without additional focusing lenses, high power pump diodes, etc.

An optically pumped semiconductor laser includes an active ring-resonator having two or more optically pumped semiconductor (OPS) structures each including a mirror-structure and a multilayer gain-structure. The mirror-structures serve as fold mirrors for the resonator axis. An optically nonlinear crystal may be included in the ring-resonator for generating second-harmonic radiation from fundamental radiation generated in the resonator. Another optically nonlinear crystal may be provided for generating third-harmonic or fourth-harmonic radiation from the second-harmonic radiation. In one example, including a third-harmonic generating crystal, a passive ring-resonator partially coaxial with the active ring-resonator is provided for circulating second-harmonic radiation to provide resonant amplification of the second-harmonic radiation for enhancing third-harmonic conversion. Apparatus for automatically maintaining the passive ring-resonator in a resonant condition for the second-harmonic radiation is disclosed.

A laser system includes an optically pumped laser resonator that produces a fundamental-wavelength beam. A temperature-tuned frequency converter outside the laser resonator converts a portion of the fundamental-wavelength beam to a frequency-converted beam. The frequency converter includes at least one temperature-tuned optically nonlinear crystal. The power and position of the frequency-converted beam are dependent on the temperature of the optically nonlinear crystal and the optical pumping power. The power and position of the frequency-converted beam are monitored. The temperature of the optically nonlinear crystal is adjusted to maintain the frequency-converted beam at a predetermined position. The optical pump power is adjusted to maintain the power of the frequency-converted beam at a predetermined level.

Solid state lasers that use non-linear optical crystals to generate frequency tripled or quadrupled output in the ultraviolet have low lifetimes due to damage to the face of the non-linear crystal through which the ultraviolet signal exits. To prevent this damage, the tripling or quadrupling crystal is provided within a controlled environment that is maintained substantially free from contaminants such as silicon-bearing and organic compounds. The tripling or quadrupling crystal is enclosed within a tubular chamber with windows on the ends of the tube that provide optical access to the entrance and exit faces of the tripling or quadrupling crystal. All heating elements and alignment elements for the crystal are outside of the chamber. Because the crystal is stored within the hermetically sealed chamber, contaminants are not available within the environment of the crystal that could interact with the energetic photons of the ultraviolet output of the frequency multiplied solid state laser. The windows and walls of the chamber are preferably made of materials that can be cleaned effectively, such as sapphire or quartz for the windows and stainless steel for the walls and flanges of the chamber.

A traveling-wave ring laser resonator includes one or more gain-elements for generating fundamental radiation and three optically nonlinear crystals. A portion of the fundamental radiation is converted to second-harmonic radiation in a first of the crystals. Remaining fundamental radiation and the second-harmonic radiation traverse a second of the optically nonlinear crystals where a portion of each is converted to third-harmonic radiation. Fundamental and second-harmonic radiation pass through the third of the optically nonlinear crystals where most of the second-harmonic radiation is converted back to fundamental radiation. The third-harmonic radiation can be delivered from the resonator as output radiation or mixed with the fundamental radiation in a fourth optically nonlinear crystal to generate fourth harmonic radiation. An optical parametric oscillator arrangement is also disclosed.

A compact optically-pumped solid-state laser designed for efficient nonlinear intracavity frequency conversion into desired wavelengths using periodically poled nonlinear crystals. These crystals contain dopants such as MgO or ZnO and / or have a specified degree of stoichiometry that ensures high reliability. The laser includes a solid-state gain media chip, such as Nd:YVO4, which also provides polarization control of the laser; and a periodically poled nonlinear crystal chip such as PPMgOLN or PPZnOLT for efficient frequency doubling of the fundamental infrared laser beam into the visible wavelength range. The described designs are especially advantageous for obtaining low-cost green and blue laser sources.

The invention discloses manufacturing method and equipment of a single optical frequency comb with high stability and high repetition frequency. The method comprises the following specific steps of: outputting femtosecond pulses with high repetition frequency, wide spectrum and pulse width less than 7 fs by using a cycle-grade femtosecond titanium sapphire oscillator; carrying out beat measurement of the CEO of the femtosecond pulses by using a single nonlinear crystal; and simultaneously locking repetition frequency and CEO frequency to a stable external microwave reference source by using a circuit feedback technology. The equipment comprises the cycle-grade femtosecond titanium sapphire oscillator, the single nonlinear crystal beat measurement fceo device and a feedback circuit device controlled on the basis of the phase lock principle. The invention has the characteristics of compact equipment structure, long locking time, high usable output power, small phase noise and the like, and is mainly applied to the scientific researches of absolute optical frequency measurement, optical clock composition, atto-second production and the like.

A distance measuring apparatus for measuring a distance to a target point in a target area comprises a laser oscillator for generating a laser beam having a first wavelength, a nonlinear crystal into which the laser beam having the first wavelength generated by the laser oscillator enters, the nonlinear crystal generating a laser beam having a second wavelength, a collimator lens at which the laser beam having the first wavelength generated by the laser oscillator and the laser beam having the second wavelength generated by the nonlinear crystal are concentrated and are transformed into parallel light flux, a laser device provided with the laser oscillator, the nonlinear crystal, and the collimator lens, an output unit for outputting the laser beam having the first wavelength and the laser beam having the second wavelength at the same time, which are emitted by the laser device, while scanning the target area, a selective reflective mirror for selectively reflecting the laser beam having the first wavelength and the laser beam having the second wavelength that are reflected at the target point in the target area, a first light receiving unit which receives the laser beam having the first wavelength selected at the selective reflective mirror and outputs a first signal, a second light receiving unit which receives the laser beam having the second wavelength selected at the selective reflective mirror and outputs a second signal, and a signal processing unit for measuring the distance to the target point in the target area by selecting one of the first signal and the second signal.

An optically pumped semiconductor pumped optical parametric oscillator (OPS-pumped OPO) includes an OPS laser resonator and an OPO resonator A portion the OPS laser resonator axis and the OPO resonator axis are collinear. An optically nonlinear crystal is located in the coaxial portion of the resonators and arranged to frequency divide fundamental radiation generated in the OPS laser resonator into signal and idler radiations. In one arrangement, the OPO laser resonator is also an OPS resonator and is arranged to generate radiation at the wavelength of the signal radiation, with the idler radiation having the difference-frequency wavelength of the signal and fundamental radiations

A light emitting device is disclosed that emits light from the surface in a broad spectral range and in a broad range of angles tilted with respect to the direction normal to the exit surface. An apparatus for generating wavelength-stabilized light is formed of a light-emitting device, an external cavity and at least one external mirror. Light emitted by the light-emitting device at a certain preselected angle, propagates through the external cavity, impinges on the external mirror and is reflected back. Light emitted at other angles does not impinge on the external mirror. Thus, a feedback occurs only for the light emitted at a preselected angle. Light impinged on the external mirror and reflected back undergoes interference with the emitted light. The interference can be constructive or destructive. Constructive interference results in a positive feedback. The positive feedback occurs, if light emitted by the light-emitting device is reflected back and reaches the active region in phase, i.e. if the phase matching between emitted and reflected light waves occurs. The positive feedback conditions are met at one or a few selected wavelengths within the luminescence spectrum of the active region. Then the apparatus generates wavelength-stabilized light. In different embodiments, an apparatus may operate as a wavelength-stabilized light-emitting diode, a wavelength-stabilized superluminescent light-emitting diode, or a wavelength-stabilized laser.Various embodiments are possible which are distinguished in a way of optical coupling between a light-emitting device and an external mirror. The coupling can be realized via the far-field zone of the light emitted by the light-emitting device, via the near-field zone, or via a single epitaxial structure.An apparatus for the frequency conversion is disclosed further comprising a non-linear crystal located within the external cavity.

A laser machining method includes A) generating, by a laser source, a laser beam having an initial wavelength between 700 and 1200 nanometers of laser pulses; B) doubling frequency of one part of the laser beam by a non-linear crystal; C) varying power throughout each emitted laser pulse so that the power profile has a maximum peak power or part of the pulse with a maximum power in an initial sub-period, and throughout an intermediate sub-period of longer duration than the initial sub-period, a lower power than the maximum power. The maximum power value is at least two times higher than the mean power throughout the laser pulse and an increase time to maximum power from a start of each laser pulse is less than 0.3 milliseconds. The machining method can concern welding highly reflective metals, copper, gold, silver, or an alloy including one of these metals.

The invention relates to a laser system including a nonlinear crystal having a first length portion and a second length portion. The nonlinear crystal disposed to receive input light from the laser for converting the input light into frequency converted light; wherein the nonlinear crystal is configured so that the first length portion of the nonlinear crystal is phase matching for the input light and the frequency converted light, and the second length portion of the nonlinear crystal is phase mismatching for the input light and the frequency converted light. Phase mismatching means may include a temperature controlling board, a clamp, or electrodes.

A optical parameter chirp pulse amplification laser system, includes a titanium gem femtosecond mode-locking pulse oscillator, a first splitting film, a CEP steady signal pulse source, an OPCPA synchronous pumping source, an OPCPA amplifier stage and compressor. In the output beam direction of the titanium gem femtosecond mode-locking pulse oscillator is the first splitting film, which divides a laser beam into a transmission light beam and a reflection light beam, and in the said transmission light beam is said CEP steady signal pulse source, OPCPA amplifier stage and compressor in order. The said CEP steady signal pulse source comprises a photonic crystal optical fiber, a chirp mirror, a period polarization lithium niobate crystal and a stretcher; said OPCPA amplifier stage comprises a first two-tone mirror, a first nonlinear crystal, a second two-tone mirror and a second nonlinear crystal; said OPCPA synchronous pumping source comprises a Q-tuning frequency-multiplier YAG laser, a narrowband titanium gem regenerating amplifier and a second splitting film, and a holophote. The invention apparatus may get a near-infrared ultrashort laser pulse output with a pulse width less than 30 femtoseconds.

A bi-directional pulsed ring laser that produces bi-directional light pulses that interact in such a way that they are phase conjugated. A nonlinear substance, such as a nonlinear crystal or fluid, that has an index of refraction that is dependent upon light intensity is located near a beam waist of the laser cavity to provide a self-lensing effect. Methods for reducing dead band beyond observable limits are also provided. The increased sensitivity of the bi-directional pulsed ring laser provides application in detecting magnetic susceptibility by detecting the change in phase between the arrival times of the bi-directional pulses at a modulator and the electrical signal of the modulator to determine the change in frequency of a coil that has magnetic susceptibility.

A compact solid-state laser array for nonlinear intracavity frequency conversion into desired wavelengths using periodically poled nonlinear crystals. The crystals contain dopants such as MgO and / or have a specified stoichiometry. A preferred embodiment comprises a microchip laser cavity that includes a solid-state gain chip, such as Nd:YVO4, which also provides polarization control of the laser; and a periodically poled nonlinear crystal chip such as PPMgOLN, for efficient frequency doubling of a infrared laser pump beam into the visible wavelength range. The described designs are especially advantageous for obtaining low-cost green and blue laser sources. The use of such high-efficiency pumps and nonlinear materials allows scaling of a compact, low-cost architecture to provide high output power levels in the blue / green wavelength range.

Method and system for providing laser light that is tunable over a relatively wide mid-infrared wavelength range, such as 2-17 .mu.m. A first noncritically phase matched nonlinear crystal receives a laser light beam and converts the light to a first cavity beam having a first selected wavelength, using optical parametric oscillation techniques. A second noncritically phase matched nonlinear crystal receives the first cavity beam and converts the light to a second cavity beam having a second selected wavelength. Where the first wavelength is tuned (e.g., by temperature change or effective path length change) over a wavelength range of 2-5 .mu.m, the second wavelength can vary over a higher and broader wavelength range, such as 3-17 .mu.m.