12 results about "Refractive index modulation" patented technology

The application discloses a kind of optical fiber side light extraction structure and method, belong to optical fiber side light extraction technical field, structure has including femtosecond grating light extraction component, filter component including filter layer and with slit light shielding layer, and detection component.The method includes: with grating diffraction separation optical signal in fiber core, with filter component filters optical signal, with detector receives signal.The application is by femtosecond laser in fiber core and writes small refractive index modulation area, with diffraction effect will transport light be introduced with specific angle to side, again cooperate external filter and metal slit and constitute spatial filter, physically block the stray light deviating from preset angle.This internal diffraction+external filter synergic mechanism avoids physical damage optical fiber surface, and realizes high purity, high directional signal extraction under micro size.

The application discloses a phase mask plate preparation method for inhibiting a Fabry-Perot effect, and comprises the following steps: a dispersion fiber grating model is established, and reflection spectrum, transmission spectrum and group delay curve of the dispersion fiber grating are obtained through simulation; an ultra-Gaussian cut-off function model is established; according to the reflection spectrum and the transmission spectrum of the dispersion fiber grating and the ultra-Gaussian cut-off function, the reflection spectrum, the transmission spectrum and the group delay curve of the optimized dispersion fiber grating are obtained through simulation, and then a refractive index modulation depth distribution curve of a grating area of the phase mask plate is obtained; the refractive index modulation depth distribution curve of the grating area of the phase mask plate is optimized to obtain an optimized refractive index modulation depth distribution curve; a diffraction efficiency distribution curve and a groove depth of the phase mask plate are calculated; and the phase mask plate is obtained according to the groove depth of the phase mask plate. According to the application, the groove depth distribution of the phase mask plate used for writing is only adjusted, the Fabry-Perot effect can be effectively inhibited, and therefore the reflection spectrum flatness of the dispersion fiber grating is improved.

This invention provides a photopolymer composition, a holographic film, and a volume holographic grating. The photopolymer composition of this invention comprises a polymer matrix, a photopolymerizable monomer, and a photoinitiator; the polymer matrix comprises linear polyurethane, and the photopolymerizable monomer comprises a compound represented by Formula I. By using linear polyurethane as the polyurethane matrix and a compound represented by Formula I as the photopolymerizable monomer, the photopolymer composition of this invention possesses high refractive index modulation capability and low viscosity, enabling the formation of a holographic film with uniform material distribution, thereby achieving high diffraction efficiency in the volume holographic grating.

This application relates to the field of optical device technology, and provides a method, device and equipment for preparing a polymer holographic optical device. The method includes: mixing a photosensitive polymer holographic material with preset nanoparticles to obtain a mixed material; the preset nanoparticles have photosensitive active groups; covering the mixed material onto a substrate; subjecting the mixed material on the substrate to a thermosetting treatment; and irradiating the thermosetting mixed material with coherent light to obtain a polymer holographic optical device, thereby improving the refractive index modulation of the polymer holographic optical device.

This invention relates to the field of fiber optic temperature measurement technology, specifically to a high-temperature sensor based on a torsion-type long-period fiber grating and its fabrication method. The fabrication process includes: fixing an optical fiber to a rotating fixture and rotating it by a preset angle to prepare an optical fiber with a preset torsional stress field; controlling a laser and a displacement platform to alternately perform fixed-point pulse irradiation and step-by-step movement to induce thermal relaxation of the stress field to prepare the grating; collecting transmission spectral data and controlling the processing equipment based on power loss values; and calculating the temperature sensitivity coefficient. In this invention, by pre-setting a torsional stress field and inducing periodic thermal relaxation of stress, dependence on photosensitive doping materials is eliminated, mechanical strength is maintained, and efficient refractive index modulation is achieved, resulting in excellent thermal stability. Combined with real-time spectral acquisition and loss analysis, a closed-loop feedback is constructed to precisely adjust irradiation parameters, improving temperature sensitivity and linearity, and solving the problems of low yield and poor long-term stability associated with traditional processes.

The present application discloses a photopolymer-based holographic recording medium, a volume holographic grating and a preparation method therefor, and a holographic device. The photopolymer-based holographic recording medium at least comprises a compound having a plurality of isocyanate reactive functional groups and a polyisocyanate-based compound, wherein the number of the isocyanate reactive functional groups is different from the number of isocyanate groups. The volume holographic grating prepared in the present application has a relatively high refractive index modulation for red, green and blue light.

This invention relates to the field of optical cable thermal aging simulation and optimization technology, specifically a method for optimizing the optical transmission performance of prefabricated optical cables in smart substations under high-temperature aging. The method includes: establishing a simulation model based on material thermodynamics and geometry to simulate the distribution and evolution of the internal temperature field of the optical cable at high temperatures; calculating the micro-variation field of the thermally induced refractive index of the fiber core material based on the temperature field, and then analyzing the mode coupling and additional loss characteristics of the optical signal; based on this, deriving the inverse refractive index modulation distribution function used to compensate for performance degradation, and converting it into a scheme for adjusting the physical parameters of the prefabricated optical cable structure. This method, through a combination of simulation modeling and reverse design, achieves active compensation and optimization for the decline in optical transmission performance caused by thermal aging, improving the transmission stability and service life of prefabricated optical cables under long-term high-temperature environments.

The application provides a kind of body holographic optical element preparation method, device and system, it is related to optical element preparation technology.Therein, the method comprises: according to refractive index modulation degree level, the refractive index modulation degree distribution diagram corresponding to the target optical element to be prepared is divided into at least one subgraph, each subgraph has the same refractive index modulation degree level;Each subgraph is sequentially filled into exposure mask subgraph according to the opening time corresponding to the refractive index modulation degree level, to obtain the target exposure mask subgraph in an exposure period;According to target exposure mask subgraph, control spatial light modulator SLM modulates incident light in exposure period, to obtain target optical element.Through the present application, the accurate modulation of refractive index modulation degree can be realized.

The application provides a photopolymer system, a grating device containing a chirp structure and a preparation method of the grating device, wherein a visible light and ultraviolet light dual initiator and an azobenzene polymerizable acrylate monomer are introduced into the photopolymer system, the acrylate group can be used as a writing monomer to participate in a copolymerization process, the azobenzene group can continuously photoisomerize during holographic exposure, the system is driven to react and crosslink by the visible light initiator and the ultraviolet light initiator in turn, the photopolymer system is recorded with interference fringes at the same time, the chirp structure is induced to be generated inside the formed volume holographic grating, the change of the grating period caused by material shrinkage is effectively compensated, the angle response bandwidth of the grating is significantly widened, the demand for the refractive index modulation of the photopolymer system is reduced, the selection range of the photopolymer system is widened, meanwhile, the aging resistance of the material system as a whole is improved, and the service life of the grating device is prolonged.