Abstract:
In a nonlinear optical medium such as the gallium arsenide, two collinear incident monochromatic waves are injected to generate a monochromatic wave. The medium induces between the three waves a propagation phase-shift that has a value π if the three waves travel a coherence length in the medium and that is compensated at the value 0 modulo 2π each time that the three waves have travelled a periodic distance in the medium. In order to significantly increase the conversion efficiency, the periodic distance between two successive bounces of total internal reflection of the waves in zig-zag is strictly less than the coherence length. The high conversion efficiency on a very short material length leads to product high-power coherent optical sources particularly with wavelengths of approximately 10 μm.
Abstract:
The method comprises positioning a diffraction grating with a two-dimensional meshing on the path of the beam to be analyzed and processing at least two interferograms of at least two different colors, each interferogram being obtained in a plane from two sub-beams with different diffraction orders. The invention can be used to analyze and correct divided wavefronts.
Abstract:
The method comprises positioning a diffraction grating with a two-dimensional meshing on the path of the beam to be analyzed and processing at least two interferograms of at least two different colors, each interferogram being obtained in a plane from two sub-beams with different diffraction orders. The invention can be used to analyze and correct divided wavefronts.
Abstract:
The application relates to a method for analyzing the wave surface of a light beam from a source to the focus of a lens. The beam illuminates a sample on the analysis plane and having a defect. A diffraction grating of the plane is a conjugate of an analysis plane through a focal system. An image is formed in a plane at a distance from the grating plane and analyzed by processing means. The invention encodes this grating by a phase function resulting from the multiplication of two phase functions, a first exclusion function defining a meshing of useful zones transmitting the beam to be analyzed in the form of light pencil beams, and a second phase fundamental function which creates a phase opposition between two light pencil beams coming out of adjacent meshes of the exclusion grating.
Abstract:
According to one aspect, the invention relates to a microbolometer array for thermal detection of light radiation in a given spectral band, comprising a supporting substrate and an array of microbolometers (300) of given dimensions, arranged in an array. Each of said microbolometers comprises a membrane (301) suspended above said supporting substrate, said membrane consisting of an element (305) for absorbing the incident radiation and a thermometric element (304) in thermal contact with the absorber, electrically insulated from said absorber element. The absorber element comprises at least one first metal/insulator/metal (MIM) structure comprising a multilayer of three superposed films of submicron-order thickness i.e. a first metallic film (311), a dielectric film (310), and a second metallic film (309), said MIM structure being able to have a resonant absorption of said incident radiation at at least one wavelength in said spectral band. The area of the microbolometer pixel covered by said membrane (301) is less than or equal to half of the total area of the microbolometer pixel.
Abstract:
According to one aspect, the invention relates to a microbolometer array for thermal detection of light radiation in a given spectral band, comprising a supporting substrate and an array of microbolometers (300) of given dimensions, arranged in an array. Each of said microbolometers comprises a membrane (301) suspended above said supporting substrate, said membrane consisting of an element (305) for absorbing the incident radiation and a thermometric element (304) in thermal contact with the absorber, electrically insulated from said absorber element. The absorber element comprises at least one first metal/insulator/metal (MIM) structure comprising a multilayer of three superposed films of submicron-order thickness i.e. a first metallic film (311), a dielectric film (310), and a second metallic film (309), said MIM structure being able to have a resonant absorption of said incident radiation at at least one wavelength in said spectral band. The area of the microbolometer pixel covered by said membrane (301) is less than or equal to half of the total area of the microbolometer pixel.
Abstract:
According to a first aspect, the present invention relates to a spectral filter suitable for filtering an incident wave at at least a first given central wavelength λ0 comprising a substrate with a through orifice and a membrane of dielectric material. The membrane is suspended above the orifice and is structured to form a set of rods organized in the form of a two-dimensional pattern (33) repeated in two directions (D1, D2), the repetition of the pattern in at least one direction being periodic or quasi-periodic, with a first period (T1) less than the central wavelength λ0.
Abstract:
The application relates to a method for analyzing the wave surface of a light beam from a source to the focus of a lens. The beam illuminates a sample on the analysis plane and having a defect. A diffraction grating of the plane is a conjugate of an analysis plane through a focal system. An image is formed in a plane at a distance from the grating plane and analyzed by processing means. The invention encodes this grating by a phase function resulting from the multiplication of two phase functions, a first exclusion function defining a meshing of useful zones transmitting the beam to be analyzed in the form of light pencil beams, and a second phase fundamental function which creates a phase opposition between two light pencil beams coming out of adjacent meshes of the exclusion grating.
Abstract:
According to one aspect, the invention relates a spectral band-pass filter, which is optimized for the transmission of an incident wave at at least a first given central wavelength λ0, and which includes: a metal grating having a thickness (t) greater than approximately λ0/50 and including at least a first set of substantially identical, parallel slots having a width (W) less than around λ0/10, and being spaced apart periodically or quasi-periodically according to a first period that is less than said first central wavelength, a layer of dielectric material having a thickness (h) and a given refractive index (ng), which is coupled to the metal grating to form a waveguide for the waves diffracted by the grating, said first period of the grating being designed such that only orders 0 and ±1 of a wave having normal incidence and a wavelength λ0 are diffracted in the layer of dielectric material, the assembly of the dielectric layer and grating being suspended, during use, in a fluid having a refractive index of close to 1.
Abstract:
According to one aspect, the invention relates a spectral band-pass filter, which is optimized for the transmission of an incident wave at at least a first given central wavelength λ0, and which includes: a metal grating having a thickness (t) greater than approximately λ0/50 and including at least a first set of substantially identical, parallel slots having a width (W) less than around λ0/10, and being spaced apart periodically or quasi-periodically according to a first period that is less than said first central el wavelength, a layer of dielectric material having a thickness (h) and a given refractive index (ng), which is coupled to the metal grating to form a waveguide for the waves diffracted by the grating, said first period of the grating being designed such that only orders 0 and ±1 of a wave having normal incidence and a wavelength λ0 are diffracted in the layer of dielectric material, the assembly of the dielectric layer and grating being suspended, during use, in a fluid having a refractive index of close to 1.