摘要:
An optical device for efficient radiation emission having a modulation region with phase matching means (1) for enhancing the phase matching between two different frequency signals propagating in the optical modulation region (1) in response to illumination by at least one incident beam (7, 8), the phase matching means (1), having a spatial variation in its refractive index (5) along the path of the incident radiation beam (7, 8). The device may be configured as a radiation source comprising a frequency conversion member (C2) for emitting a beam of radiation (553) in response to irradiation by one or more input beams (507), the emitted beam (553) having a frequency different to that of the one or more input beams (507), the one or more input beams (507) all being produced within a lasing cavity (defined by M3, M4, M5, M6 and output coupler (523)) and said frequency conversion member (C2) being located within said lasing cavity. The invention also extends to an imaging system using the radiation source.
摘要:
A semiconductor laser comprises an active region (12) which, in response to a pumping energy applied thereto, can produce a stimulated emission of radiation with a central wavelength (λ) in the far infrared region, and a confinement region (16, 18, 22) suitable for confining the radiation in the active region (12), and comprising at least one interface (16a, 16b, 22a) between adjacent layers that is capable of supporting surface plasmon modes generated by an interaction of the interface with the radiation. The confinement region (16, 18, 22) comprises a wave-guide layer (16) which is delimited on opposite sides by a first interface and by a second interface (16a, 16b). The guide layer (16) is doped in a manner such that the first and second interfaces (16a, 16b) are capable of supporting the plasmon modes, respectively, and is of a thickness (d) such as to bring about the accumulation of the plasmon modes in proximity to the first and second interfaces (16a, 16b), outside the layer (16), and substantially a suppression of the plasmon modes, inside the layer.
摘要:
A method for measuring an absorption characteristic of a sample comprises: providing a microstrip waveguide comprising a ground plane, an elongate conductive strip having a first end and a second end, and a dielectric substrate separating the ground plane from the elongate strip such that the strip extends from its first end to its second end in a plane substantially parallel to the ground plane; emitting electromagnetic radiation from a first intermediate position along the microstrip waveguide, said first intermediate position being a position between the first and second ends of the strip, such that said radiation propagates along the waveguide in a direction towards the second end; positioning a sample at a position external to the microstrip waveguide and between the first intermediate position and a second intermediate position along the microstrip waveguide, the second intermediate position being a position between the first intermediate position and the second end, such that at least a portion of the sample is exposed to the evanescent electric field of the propagating radiation; and detecting at least one characteristic of the propagating radiation at said second intermediate position. Corresponding apparatus is also disclosed.
摘要:
A method of generating radiation comprises: manufacturing a structure comprising a substrate supporting a layer of InGaAs, InGaAsP, or InGaAlAs material doped with a dopant, said manufacturing comprising growing said layer such that said dopant is incorporated in said layer during growth of the layer; illuminating a portion of a surface of the structure with radiation having photon energies greater than or equal to a band gap of the doped InGaAs, InGaAsP, or InGaAlAs material so as to create electron-hole pairs in the layer of doped material; and accelerating the electrons and holes of said pairs with an electric field so as to generate radiation. In certain embodiments the dopant is Fe. Corresponding radiation detecting apparatus, spectroscopy systems, and antennas are described.
摘要:
A method of generating radiation comprises: manufacturing a structure comprising a substrate supporting a layer of InGaAs, InGaAsP, or InGaAlAs material doped with a dopant, said manufacturing comprising growing said layer such that said dopant is incorporated in said layer during growth of the layer; illuminating a portion of a surface of the structure with radiation having photon energies greater than or equal to a band gap of the doped InGaAs, InGaAsP, or InGaAlAs material so as to create electron-hole pairs in the layer of doped material; and accelerating the electrons and holes of said pairs with an electric field so as to generate radiation. In certain embodiments the dopant is Fe. Corresponding radiation detecting apparatus, spectroscopy systems, and antennas are described.
摘要:
The present invention provides a method of forming coatings of at least two different coating molecules on at least two electrodes, the method comprising: (a) providing an array of at least two individually-addressable electrodes, (b) allowing a layer of a masking molecule to adsorb onto all electrodes, (c) inducing electrochemical desorption of the masking molecule from at least one but not all electrodes to expose a first set of exposed electrodes, (d) allowing a first coating molecule to adsorb onto the first set of exposed electrodes, (e) exposing all electrodes to a masking molecule to allow adsorption of the masking molecule onto all electrodes, (f) inducing electrochemical desorption of masking molecule from a second set of electrodes to expose a second set of exposed electrodes, (g) allowing a second coating molecule to adsorb onto the second set of exposed electrodes.
摘要:
The invention relates to a method of detecting a structural change in a molecule, said molecule being attached to a surface, said surface being electrically conductive, wherein the phase of the electrochemical impedance at said surface is monitored, and wherein a change in the phase in the electrochemical impedance at said surface indicates a change in the structure of said molecule. The invention further relates to methods for making arrays having molecules such as, polypeptides attached to electrically conductive surfaces such as electrodes, and to arrays.