11 results about "Nonlinear absorption" patented technology

The invention provides a method for regulating and controlling the nonlinear absorption type of a DAST-based composite film and a preparation process of the DAST-based composite film, and relates to the technical field of nonlinear optical materials. The method comprises the following steps: compounding a guest photoelectric sensitive material DAST and a subject flexible material PMMA by adopting a blade coating technology to obtain a binary DAST / PMMA subject-guest composite film; during the process, the mass fraction of the object photoelectric sensitive material in the composite film is adjusted, so that mutual conversion between a nonlinear anti-saturated absorption behavior and a saturated absorption behavior of the composite film in a femtosecond trepanning Z scanning laser system is successfully realized. Compared with existing nonlinear absorption type regulation and control technologies such as band gap engineering of two-dimensional inorganic materials, micro-nano structure construction of organic materials, functional group modification and the like, the regulation and control method is simpler, lower in cost and more beneficial to industrial processing, and has good practical application potential in the fields of laser protection, laser mode locking, optical switches and the like.

The invention provides a large-modulation-depth dynamic saturable absorber mirror and a preparation and working method thereof, the large-modulation-depth dynamic saturable absorber mirror comprises a vanadium dioxide nano film and a gold film silicon substrate high-reflection mirror, and the film is deposited on the upper layer of a gold film of the gold film high-reflection mirror through a direct current magnetron sputtering technology to form a dynamic saturable absorber mirror device; the core mechanism is that when the dynamic saturable absorption mirror is driven by enhanced light intensity in a cavity, phase transformation and optical property dynamic transformation occur, starting from low reflectivity and high loss of a vanadium dioxide insulating phase, the state is converted into a vanadium dioxide mixed phase saturable absorption state through phase transformation equivalent nonlinear absorption, and then the state is converted into a metallic state saturable absorption state; and finally, the metal-state saturable absorption is completely saturated, so that the large-modulation-depth dynamic saturable absorption mirror is realized. According to the invention, the modulation depth of the saturable absorber mirror can be effectively improved and flexibly adjusted; and the basic temperature of the device can be regulated and controlled in a passive / active manner, so that the universality and adaptability of system application are enhanced.

The invention relates to a method and a system for manufacturing a polarizing body holographic grating (PVG) lens. The method comprises the following steps: a) providing a PVG lens blank; b) scanning on the PVG lens blank by using a first wavelength laser beam along a preset cutting path to form a stress concentration line; and c) scanning along the same cutting path by using a laser beam with a second wavelength, and applying thermal stress loading to the stress concentration line to guide the crack to expand from the stress concentration line so as to separate the lens blank along the cutting path. According to the invention, a two-step separation method of internal preset fracture path and external thermal shock guiding is adopted. A first wavelength laser beam (such as ultrafast laser of picosecond and the like) can form an accurate and lossless microscopic modified chain as a stress concentration line in a substrate through nonlinear absorption under the condition of not damaging the surface of a material due to the cold working characteristic of the first wavelength laser beam. The surface micro-cracks are eradicated from the source. And a second wavelength laser beam (such as infrared laser of COs and the like) generates a moving and high-gradient thermal stress field on the surface of the substrate along a preset path by utilizing the thermal effect of the second wavelength laser beam. And the stress field accurately acts on the internal fragile stress concentration line to guide cracks to controllably and smoothly expand, so that mechanical-contact-free guided fracture is realized.

The application relates to a method for enhancing the nonlinear optical performance of SnS2 nanosheets through electrostatic doping. First, SnS2 nanosheets are prepared on a fluorine-doped tin oxide (FTO) substrate by a chemical vapor deposition method, and then hydrogen ion intercalated SnS2-H + The electrostatic doping causes the band gap to shrink and a strong built-in electric field to be generated, so that the nonlinear optical performance of the material is enhanced. In addition, the saturated absorption response of the material enables the application to an optical neural network as a nonlinear activation function, and exhibits application potential in machine learning tasks. The SnS2-H + The application establishes a promising and convenient nonlinear optical material, and provides new insights for the design exploration and simple synthesis of high-performance nonlinear absorption materials.

This application provides a tunable optical pulse source chip, relating to the field of semiconductor optoelectronic integrated device technology. The optical pulse source chip includes: a gain region for generating and amplifying an optical signal; a pulse selection region for receiving an external periodic electrical signal to form a periodically switching switching window, through which the amplified optical signal passes or is blocked; and a saturable absorption region for nonlinearly absorbing the optical signal passing through the pulse selection region to achieve mode locking, thereby generating and outputting an optical pulse. The repetition frequency of the optical pulse is tunable by controlling the frequency of the periodic electrical signal. This application integrates the gain region, pulse selection region, and saturable absorption region monolithically, and uses a periodic electrical signal to control the switching window of the pulse selection region. The output optical pulse repetition frequency is independently controlled by the frequency of the external electrical signal, decoupling the repetition frequency from the cavity length, thus enabling a wide-range, continuously tunable pulse repetition frequency.

The invention discloses a laser coupling system and laser processing equipment. The laser coupling system comprises a first laser source, a second laser source and a third laser source which are used for providing three beams of laser; the polarization preprocessing module is used for adjusting the polarization states of lasers emitted by the first laser source and the second laser source to be in a preset relation and combining the lasers into first combined light, and the first combined light comprises laser components of the first polarization state and the second polarization state; the electric control polarization switching module is arranged on a light path of the first combined light beam and used for receiving signals and modulating the overall polarization state of the first combined light beam; the polarization beam splitting and combining module is provided with a main input end, an auxiliary input end and an output end, the main input end receives the modulated light beam, the auxiliary input end receives the laser emitted by the third laser source, and second combined beam light is formed through selective coupling. According to the technical scheme, coupling of the main laser and the auxiliary laser can be flexibly switched, under the condition that the total energy is lower than the energy needed by the single-beam main laser to reach the threshold value, nonlinear absorption and modification of the material can be efficiently triggered, and precise machining threshold value breakthrough under lower energy input is achieved.

This invention provides a multiphysics-coupled molecular dynamics simulation method and system for femtosecond laser ablation, comprising: establishing an atomic model of a wide-bandgap semiconductor material and its corresponding electronic grid; inputting laser parameters and material parameters and initializing field variables; introducing a carrier concentration evolution equation and updating the laser intensity distribution within the material based on the Drude model; considering the bandgap energy consumption term of the valence band electron transition process under femtosecond laser irradiation, improving the laser heat source term in the electronic temperature equation, updating the electronic temperature, and then obtaining the atomic-scale behavioral evolution through energy exchange between the electronic system and the lattice system, and outputting the results. This invention introduces the nonlinear absorption of femtosecond laser ablation of wide-bandgap semiconductor materials into a dual-temperature model-molecular dynamics model coupling framework, realizing a unified coupled simulation of energy deposition, carrier evolution, transient optical response, and material removal behavior of wide-bandgap semiconductor materials under femtosecond laser irradiation.

The invention discloses a femtosecond laser induced fused quartz surface oxygen vacancy defect micro-area prefabrication and selective repair method and system, and belongs to the field of laser precision machining and optical material modification. According to the method, irradiation parameters of femtosecond laser on the surface of fused quartz in an oxygen-containing atmosphere are controlled, and the nonlinear absorption effect of the femtosecond laser is utilized, so that two functions are realized: firstly, oxygen vacancy defects with quantitative concentration can be controllably prefabricated in a specified micro-area, and the problem that atomic-scale defects are difficult to position and characterize is solved; and 2, performing selective bonding repair on the positioned oxygen vacancy defect, so that the chemical composition of the defect area is recovered to be close to an ideal stoichiometric ratio. According to the system, a visual positioning module, a parameter mapping module and a cooperative control module are integrated, and full-automatic accurate operation is achieved. The surface roughness change of the area repaired through the method is smaller than 0.04 nm, the method has the advantages of being free of damage, controllable and high in precision, and an effective technical approach is provided for improving the laser damage threshold value of the fused quartz optical element.

This application provides an optical fiber coupling end for femtosecond laser transmission optical cables, including a substrate with an internal through-hole in the center of the substrate, a fiber fixing tube sleeved inside the internal through-hole, a front sleeve and a rear sleeve respectively at both ends of the substrate, the fiber fixing tube having a hollow inner cavity, the hollow inner cavity communicating with the interior of the front sleeve and the rear sleeve, one end of the rear sleeve being connected to the optical cable, the hollow fiber in the optical cable passing through the rear sleeve to extend into the hollow inner cavity, the end of the hollow inner cavity near the front sleeve having an optical fiber sleeve, the optical fiber sleeve fixing the hollow fiber end, an annular cavity between the internal through-hole and the fiber fixing tube, the substrate having a water inlet and a water outlet communicating with the annular cavity, which solves the problem of heat accumulation at the coupling end face of femtosecond laser transmission optical fibers, and allows for convenient structural optimization by using vacuum to solve problems such as nonlinear absorption and pulse width expansion of the laser.

According to the method and system for modifying the two-dimensional material through the laser and the two-dimensional material, the two-dimensional material to be machined is fixed to the electrode and leveled, the accuracy and stability of the relative position between the area to be modified and the laser focus in the subsequent laser machining process are guaranteed, and a solid foundation is laid for high-precision modification. Ultrafast laser parameters of an ultrafast laser are set, the requirement that the pulse width is larger than 1 ps is determined, and the unique cold machining mechanism of interaction of ultrafast laser and substances is fundamentally utilized; when ultrafast laser with the pulse width larger than 1ps acts on the two-dimensional material, laser energy is absorbed within the time scale far faster than material lattice thermal diffusion due to the extremely high peak power and the extremely short acting time of the ultrafast laser, the nonlinear absorption process is mainly triggered, and therefore accurate removal or modification of the material can be achieved with extremely small thermal influence, and the material can be effectively removed or modified. And melting, splashing and thermal damage caused by traditional long-pulse laser processing are avoided.

The invention provides an indium tin oxide thin film for enhancing terahertz emission and a preparation method of the indium tin oxide thin film, and belongs to the technical field of nonlinear optics and terahertz. The method comprises the following steps: depositing an indium tin oxide (ITO) film on a substrate by adopting a magnetron sputtering process; and the thin film is placed in a vacuum environment to be subjected to rapid thermal annealing treatment. The core of the method is that the annealing time and the annealing temperature are accurately controlled, and the thin film is regulated and controlled to be in a middle semitransparent state which is converted from opaque to full-transparent. Experiments show that the ITO thin film in the semitransparent state maintains high nonlinear absorptivity in a near-infrared pumping wave band while ensuring certain crystallization quality, so that the emission intensity of terahertz generated by the ITO thin film is obviously higher than that of a full-transparent thin film which is annealed for a long time. According to the terahertz emission source, the problem that the nonlinear optical conversion efficiency is reduced due to excessive pursuit of film transparency in the prior art is solved, and a terahertz emission source preparation scheme which is simple in process, compatible with a CMOS (complementary metal oxide semiconductor) process and efficient is provided.