64 results about "Optical limiter" patented technology

An optical slicer for generating an output spot comprising an image compressor which receives a substantially collimated input beam and compresses the beam, wherein the input beam, if passed through a focusing lens, produces an input spot; an image reformatter which receives the compressed beam to reformat the beam into a plurality of sliced portions of the compressed beam and vertically stacks the portions substantially parallel to each other; and an image expander which expands the reformatted beam to produce a collimated output beam which, if passed through the focusing lens, produces the output spot that is expanded in a first dimension and compressed in a second dimension relative to the input spot.

An intracavity resonant Fabry-Perot saturable absorber (R-FPSA) induces modelocking in a laser such as a fiber laser. An optical limiter such as a two photon absorber (TPA) can be used in conjunction with the R-FPSA, so that Q-switching is inhibited, resulting in laser output that is cw modelocked. By using both an R-FPSA and a TPA, the Q-switched modelocked behavior of a fiber laser is observed to evolve into cw modelocking.

Inorganic crystals having one or more species of dopant ions which are photo-reactive are used as visible and or infrared light optical limiters to protect against laser radiation exposure while permitting passage of the visible and or infrared light spectrum at least until exposed to high energy laser radiation. The dopant ions are selected from ions of transition metals. The exposure of these ions within the transparent crystalline matrix either photo-ionize or are elevated to an excited state and thereby absorb or otherwise attenuate the passage of the laser beam radiation sufficiently to protect human eyes or photo-sensitive equipment. The crystals may be fabricated into such items as lenses for use in eyeglasses or on shields of flight helmets to protect the eyes of aircraft pilots.

The present invention in one aspect relates to a low-cost, nano-graphene based broadband optical limiter with limiting properties superior to current standards, carbon fullerenes (C₆₀) solutions and carbon black suspensions. The broadband optical limiter includes a plurality of graphene nano-sheets, and a base material in which the plurality of graphene nano-sheets is distributed. The base material can be liquid or gel matrix.

A reversible optical energy limiting device comprises a waveguide forming an optical path between an input end and an output end, and an optical energy responsive material located in the optical path for reflecting at least a portion of optical energy received from the input end back toward the input end when the optical energy exceeds a predetermined threshold. The optical energy responsive material does not reflect optical energy when it drops below the predetermined threshold, and thus propagation of optical energy from the input end to the output end is automatically resumed when the optical energy drops below the predetermined threshold. The optical energy responsive material may extend across the optical path an acute angle relative to the longitudinal axis of the optical path so that back-reflected light does not re-enter the optical system.

The invention relates to an optical limiter with adjustable threshold, comprising a nonlinear refractive material, a diaphragm and a supporting encapsulation device; the nonlinear refractive material and the diaphragm are arranged in the supporting encapsulation device; wherein, the nonlinear refractive material is arranged in front of the diaphragm; the incident laser beam sequentially passes through the nonlinear refractive material and the diaphragm; the diaphragm is provided with a clear aperture with changeable size; and the position of the diaphragm corresponding to the nonlinear refractive material is changed by an adjusting device. Compared with the prior art, the optical limiter utilizes the combination of the thermal lens effect of the nonlinear refractive material and the changeable diaphragm, realizes the optical limiter with adjustable threshold, has simple structure, easy preparation and low cost, has convenient, online and real-time adjustment of the limiting threshold, can be applied to various situations, provides guarantee for the safe use of precise optical devices (including human eyes), and prompting the improvement of the laser protection technique.

A system and method for producing bulk GaAs with an increased carrier lifetime of at least 10 microseconds is provided. The system and method of producing the GaAs crystal involves using a technique called low pressure hydride vapor phase epitaxy (LP-HVPE). In this technique, a gas containing Ga (typically GaCl) is reacted with a gas containing As (typically AsH₃) at the surface of a GaAs substrate. When grown under the proper conditions, the epitaxial, vapor grown GaAs crystal has ultra-long free carrier lifetimes of at least one order of magnitude greater than that of the previous lifetime of 1 microsecond. This very long free carrier lifetime GaAs will be particularly useful as a semiconductor radiation detector material and is also expected to be useful for many other applications than include medical imaging, solar cells, diode lasers, and optical limiters and other applications.

An optical limiter comprises a glass backing, a glass cover, and a layer of a phase changing material placed between said glass backing and said glass cover, the phase changing material comprising a transparent matrix having embedded particles of material that changes its optical properties due to temperature induced phase change of said material. The optical properties may change from transparent to reflective, from transparent to refractive or from transparent to scattering. The phase changing material is preferably at least one material selected from the group consisting of the elements Antimony, Bismuth, Cadmium, Lead, Tin and Indium and low-melting-point alloys of two or more of these elements. Two or more layers of phase changing materials may be used in a stack configuration, with each of the phase changing materials having a unique melting temperature.

According to some aspects, a transmissive and all-dielectric optical component/limiter with great cutoff efficiency using Vanadium Dioxide (VO₂) as the active component is disclosed. In some embodiments, Vanadium dioxide is used for an optical limiter due to the large contrast in optical constants upon undergoing the semiconductor to metal phase transition. When triggered optically, this transition occurs within 60 fs, making the device suitable for an ultrafast laser environment. In addition, the phase transition threshold is tunable by applying stress or doping; therefore, the device cutoff intensity can be adjusted to fulfill specific requirements.

The invention discloses an ultrashort pulse optical limiter based on an optical Kerr effect. The ultrashort pulse optical limiter comprises a polarizer, a first quarter-wave plate, a first lens, optical Kerr media, a second lens, a second quarter-wave plate, a polarization analyzer and a diaphragm which are sequentially arranged in the direction of incident light. The first quarter-wave plate and the second quarter-wave plate are orthogonal in the long axis direction, and the polarization detection direction of the polarization analyzer is parallel to the polarization direction of the polarizer. According to the ultrashort pulse optical limiter based on the optical Kerr effect, the polarizer and the first quarter-wave plate are combined to generate elliptically polarized light, the optical Kerr effect generated in the optical Kerr media is further utilized, the polarization ellipse rotation and self-focusing effect are generated through abduction, part of incident light is intercepted when passing through the polarization analyzer and the diaphragm, and accordingly light amplitude limiting output can be achieved. The ultrashort pulse optical limiter based on the optical Kerr effect has the advantages of being high in linear transmissivity, high in response speed, extremely wide in bandwidth, simple in structure and low in cost, thereby being quite suitable for designing and manufacturing ultrashort pulse broadband laser protection devices.

The invention relates to a passive optical limiter having a nonlinear material capable of switching in a predetermined optical band from a transparent state to an opaque state as a function of the power of an incident laser beam. The nonlinear material is an organic dye which comprises molecules derived from 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene into which a nitrogen atom is inserted at the meso position, referred to as aza-bodipy molecules, and which have conjugated π chains functionalized so as to exhibit absorption for two photons around an incident beam wavelength lying between 1.45 μm and 1.6 μm.