245 results about "Optical nonlinearity" patented technology

A novel method for high power optical amplification of ultrashort pulses in IR wavelength range (0.7-20 Ãm) is disclosed. The method is based on the optical parametric chirp pulse amplification (OPCPA) technique where a picosecond or nanosecond mode locked laser system synchronized to a signal laser oscillator is used as a pump source or alternatively the pump pulse is created from the signal pulse by using certain types of optical nonlinear processes described later in the document. This significantly increases stability, extraction efficiency and bandwidth of the amplified signal pulse. Further, we disclose five new practical methods of shaping the temporal and spatial profiles of the signal and pump pulses in the OPCPA interaction which significantly increases its efficiency. In the first, passive preshaping of the pump pulses has been made by a three wave mixing process separate from the one occurring in the OPCPA. In the second, passive pre-shaping of the pump pulses has been made by spectral filtering in the pump mode-locked laser or in its amplifier. In the third, the temporal shape of the signal pulse optimized for OPCPA interaction has been actively processed by using an acousto-optic programmable dispersive filter (Dazzler) or liquid crystal light modulators. In the fourth alternative method, the signal pulse intensity envelope is optimized by using passive spectral filtering. Finally, we disclose a method of using pump pulses which interact with the seed pulses with different time delays and different angular orientations allowing the amplification bandwidth to be increased. In addition we describe a new technique for high power IR optical beam delivery systems based on the microstructure fibres made of silica, fluoride or chalcogenide glasses as well as ceramics. Also we disclose a new optical system for achieving phase matching geometries in the optical parametric interactions based on diffractive optics. All novel methods of the ultrashort optical pulse amplification described in this disclosure can be easily generalized to other wavelength ranges.

An optical neural network is constructed based on photonic integrated circuits to perform neuromorphic computing. In the optical neural network, matrix multiplication is implemented using one or moreoptical interference units, which can apply an arbitrary weighting matrix multiplication to an array of input optical signals. Nonlinear activation is realized by an optical nonlinearity unit, which can be based on nonlinear optical effects, such as saturable absorption. These calculations are implemented optically, thereby resulting in high calculation speeds and low power consumption in the optical neural network.

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.

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.

An optical parametric circuit for separating an input signal light and a wavelength-converted light even when the wavelength difference is small is provided. The optical parametric circuit includes: a nonlinear Mach-Zehnder interferometer which includes a first optical path and a second optical path; optical dispersive mediums and second-order optical nonlinear mediums provided in the first and second optical paths; wherein optical dispersive medium and second-order optical nonlinear medium in the first optical path are placed in the reverse order of optical dispersive medium and second-order optical nonlinear medium in the second optical path.

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

The invention provides an optical neural network method for realizing the digital recognition. The optical neural network method comprises a step of acquiring digital image features and a step of constructing an optical neural network. The optical neural network is composed of an optical interference module, an optical nonlinear module and a detector array, and the optical interference module comprises a Mach-Zehnder interferometer array and a variable optical attenuator, and can realize any matrix multiplication. The optical non-linear module is composed of a saturable absorber and other devices with the non-linear effects, and can realize the function of an activation function in an artificial neural network. According to the method, the calculation time is shortened through optical calculation, and the calculation energy consumption is reduced.

The invention discloses a double-beam multi-functional z scanning optical non-linear measuring device and a double-beam multi-functional z scanning optical non-linear measuring device method. The device uses two light sources and can conveniently switch the light sources; an adjustable attenuation slice is adopted, so laser power is continuously adjustable from 0 and 100 percent; an acoustic optical modulator and a signal generator are adopted, so the pulse width and pulse period of emergent laser are adjustable; and transmission open hole and transmission closed hole data of a sample can be measured and reflecting open hole and transmission open hole data of the sample can also be measured. The device and the method not only can measure nonlinear absorption coefficient and nonlinear refractive index of a transparent sample, but also can measure nonlinear refractive index of a nontransparent sample; and a cold light source serving as an illumination light source is added into the device, a CCD camera is used for observing surface appearance of the sample and an optical filter is used for filtering the effect of the laser, so the measuring accuracy and correctness of the nonlinear absorption coefficient and nonlinear refractive index of the transparent sample and a partially transparent sample are enhanced.

A laser device is provided for generating an ultraviolet output. The device comprises a laser having at least one diode-pumped alkali metal vapor gain cell for generating a near infrared laser output, and at least two optically-nonlinear crystals. In one particular embodiment, the laser uses a Rb gas cell and generates radiation at a wavelength of about 199 nm and at least 200 mW of power with a linewidth of less than 10 GHz. In another embodiment, narrow linewidth UV light is generated at 265 nm.

The present invention relates to an all-optical-fibre adjustable bandwidth continuous spectrum laser pump source (FBCSL) for ultraflat wideband Raman amplification, belonging to the field of high-speed wideband optical fibre communication technology. It adopts a high optical non-linear optical fibre (HNL-DSF) with approaching flat zero dispersion characteristics at Raman laser wavelength place as gain medium, and on the two ends of the above-mentioned HNL-DSF) a wideband reflector can be connected to form all the optical fibre Fabry-Perot (F-P) adjustable bandwidth continuous spectrum Raman laser or a wideband wavelength division multiplexing optical fibre coupler is connected to form all-optical-fibre circular cavity adjustable bandwidth continuous spectrum Raman laser.

An optical parametric oscillator (OPO) comprises a resonant cavity for signal light, and an optically non-linear medium disposed in the resonant cavity for converting pump light into the signal light, wherein the resonant cavity is arranged so that in operation signal light is repeatedly output from and returned to the optically non-linear medium along a signal light path in a continuously repeating cycle, and the OPO comprises delay means for extending the time taken for signal light output from the optically non-linear medium in operation to return to the optically non-linear medium along the signal light path.

The invention relates to a z scanning optical nonlinear measurement device and method capable of observing and monitoring in real time. The device mainly comprises a light source modulating and monitoring part, a data collecting part and a luminance observing part. The device adopts two light sources, so that the light sources can be switched conveniently, the pulse width and the pulse period of an emitted laser can be controlled through a signal generator, and the power is adjustable; the data of a transmission open hole and a transmission closed hole of a measured sample can be measured; and the data of a reflection open hole can be measured. According to the invention, the device and the method are suitable for not only the measurement of the nonlinear absorption coefficient and the nonlinear refractive index of a transparent material, but also the nonlinear measurement of an opaque material. A micro-objective, a lighting source and a CCD (Charge Coupled Device) camera are added for a sample moving platform in the device, so that the surface feature of the sample can be observed in real time, and the impact on the measurement data caused by the change of the feather of the sample can be avoided. While an oscilloscope is added to monitor the wave form and the power of the acting laser in real time, and the precision and the accuracy of the nonlinear measurement of material are improved.

To optimise the transformation rate (efficiency) in the optical frequency conversion of laser beams of ultra-short light pulses in optically non-linear media such as a crystal (56), a double refracting crystal (54) is arranged in the beam path before the optically non-linear medium (56). The length of the double refracting crystal (54) is selected and the orientation of its optical crystal axis in relation to the propagation direction of the laser beams involved in the frequency conversion is set such that the change caused by the double refracting crystal (54) in the location, time and direction of incidence of the laser pulses (14) and (16) on the optically non-linear medium (56) and the resulting change in the spatial and temporal overlap of the laser pulses in the optically non-linear medium (56) for optical frequency conversion in the crystal (56) give a conversion efficiency which is higher than the conversion efficiency which would be achieved without the double refracting crystal (54).

The invention discloses an optical nonlinearity measuring device and a measuring method for nonlinearity thick photonics materials, and belongs to the technical field of nonlinearity photonics materials and nonlinearity photonics measurement. Tophat type laser pulses serve as probe light, a reference standard sample with the suitable thickness is selected according to the thickness of a sample to be measured, the reference standard sample and the sample to be measured are subjected to Z scanning measurement respectively, energy of incident light is adjusted to obtain the same normalization transmittance peak-to-valley values, and a nonlinearity refraction coefficient of the sample to be measured is obtained by data processing. The optical nonlinearity measuring device and the measuring method for nonlinearity thick photonics materials are suitable for nonlinearity photonics materials of which the thicknesses exceed a Rayleigh length.