Abstract:
One aspect of the present invention concerns scanning acoustic microscopes in which sound waves used for imaging purposes are generated by an opto-acoustical process. A scanning acoustic microscope of the present invention includes an opto-acoustic transducer assembly having a substrate. Formed on or in the substrate of the opto-acoustic transducer assembly is a layer of opto-acoustic material. When pulsed light waves impinge the layer of opto-acoustic material, pulsed sound waves are created. An acoustic lens also formed in the substrate focuses the pulsed sound waves which are then used to probe the physical and mechanical properties of a sample object. Pulsed sound waves reflecting off the sample object return to the opto-acoustic transducer where the pulsed sound waves impinge the layer of opto-acoustic material. The impinging sound waves change at least one optical property of the layer of opto-acoustic material. This change, which is dependent on changes to the pulsed sound waves caused by the interaction of the pulsed sound waves and the sample object, is then sensed using pulsed light waves. In one possible embodiment of the present invention, the layer of opto-acoustic material is deposited on the substrate in a plurality of non-contiguous concentric rings. The plurality of non-contiguous concentric rings operates as an acoustic analogue of a Fresnel lens.
Abstract:
Light emitting devices having a vertical optical path, e.g. a vertical cavity surface emitting laser or a resonant cavity light emitting or detecting device, having high quality mirrors may be achieved using wafer bonding or metallic soldering techniques. The light emitting region interposes one or two reflector stacks containing dielectric distributed Bragg reflectors (DBRs). The dielectric DBRs may be deposited or attached to the light emitting device. A host substrate of GaP, GaAs, InP, or Si is attached to one of the dielectric DBRs. Electrical contacts are added to the light emitting device.
Abstract:
A vertical cavity, surface emitting laser (VCSEL) device (10, 10′) has a substrate (12) and, disposed over a surface of the substrate, a Group III nitride buffer layer (14) and a mesa structure containing at least a portion of an n-type Group III nitride layer (16). The VCSEL device and mesa structure further include a first multilayer dielectric mirror stack (18a), that is embedded within the first Group III nitride layer by the use of a lateral edge overgrowth (LEO) process; a p-type Group III nitride layer (26); and a p-n junction between the n-type Group III nitride layer and the p-type Group III nitride layer. The p-n junction contains an active multiquantum well region (24). Also contained in the mesa structure is a dielectric (silicon dioxide) layer (20) having a current constricting aperture (20a). The dielectric layer and aperture are buried within one of the n-type Group III nitride layer or the p-type Group III nitride layer, also by the use of the LEO process. A second multilayer dielectric mirror stack (18b) is disposed on top of the mesa structure and over the p-type Group III nitride layer. The first and second multilayer dielectric mirror stacks define a resonant optical cavity structure that passes through the aperture, and that supports an emission of less than 500 nm in the blue/green or NUV spectral regions.
Abstract:
A Magneto-Optoelectronic Device MOD (10) includes a magnetic sensing device (12), such as a magnetoresistive device or a magnetic tunnel junction device, that is combined with a semiconductor light emitter (14), such as a LED or a laser diode, to create a compact integrated device where changes in an ambient magnetic field are expressed as changes in an optical beam intensity emanating from the MOD. Using the MOD (10) the magnetic field related information can be transmitted by a light wave over very large distances through some medium (34), for example, through free space and/or through an optical fiber.
Abstract:
A Magneto-Optoelectronic Device MOD (10) includes a magnetic sensing device (12), such as a magnetoresistive device or a magnetic tunnel junction device, that is combined with a semiconductor light emitter (14), such as a LED or a laser diode, to create a compact integrated device where changes in an ambient magnetic field are expressed as changes in an optical beam intensity emanating from the MOD. Using the MOD (10) the magnetic field related information can be transmitted by a light wave over very large distances through some medium (34), for example, through free space and/or through an optical fiber.
Abstract:
Group II-VI compound semiconductor light emitting devices which include at least one II-VI quantum well region of a well layer disposed between first and second barrier layers is disclosed. The quantum well region is sandwiched between first and second cladding layers of a II-VI semiconductor material. The first cladding layer is formed on and lattice matched to the first barrier layer and to a substrate of a III-V compound semiconductor material. The second cladding layer is lattice matched to the second barrier layer. The quantum well layer comprises a II-VI compound semiconductor material having the formula A.sub.x B.sub.(1-x) C wherein A and B are two different elements from Group II and C is at least one element from Group VI. When the second cladding layer has a p-type conductivity, a graded bandgap ohmic contact according to the present invention can be utilized. The graded bandgap contact can be a single continuously graded II-VI p-type region or a plurality of cells with each of the cells having first and second thin layers of first and second p-type II-VI semiconductor materials respectively. Another embodiment of the present invention discloses a monolithic multicolor light emitting element capable of emitting four colors and a method for fabricating same. The monolithic multicolor element includes four II-VI semiconductor light emitting devices formed on a single III-V substrate.
Abstract:
An optical-acoustic transducer structure includes at least one metal or semiconducting film in which a part of a pump light pulse is absorbed to generate a sound pulse; and at least one dielectric film. The thicknesses and optical properties of the at least one metal or semiconducting film and the at least one dielectric film are selected so that a returning sound pulse results in a measurable change in the optical reflectivity and/or some other optical characteristic of the transducer structure. The transducer structure includes a resonant cavity, and an output surface that is shaped so as to provide no significant focusing of generated sound waves when the sound waves are launched towards a surface of the sample.
Abstract:
A particle detector has a chamber defining a pathway that a target particle follows between an entry and an exit point, a solid-state energy source such as an LED, and a re-emission sensor. The energy source imparts energy to the particle between the two points, and the sensor includes an arcuate or multi-planar lens to focus energy re-emitted by the particle. The particle is identifiable by its re-emitted energy spectrum. A scanner re-directs the beam from a single energy source to track the particle between the entry and exit points. Alternatively, the energy source is a plurality of source elements that each scan the particle at a single position. Another embodiment is a chipscale detector system wherein energy source elements are disposed on a source layer, sensor elements are disposed on a sensor layer, and one or more target particles to be detected are retained on a capture layer disposed therebetween.
Abstract:
A light emitting device includes a first active region, a second active region, and a tunnel junction. The tunnel junction includes a layer of first conductivity type and a layer of second conductivity type, both thinner than a layer of first conductivity type and a layer of second conductivity type surrounding the first active region. The tunnel junction permits vertical stacking of the active regions, which may increase the light generated by a device without increasing the size of the source.
Abstract:
A portable monitoring device for whole-body monitoring can include a receiver configured to receive wireless signals representing real-time neural activity from a neural sensor and to process the wireless signals into digital signals. The portable monitoring device can also include a first processor coupled to the receiver configured to receive the digital signals from the receiver and a programmable processor coupled to the first processor. The programmable processor can be configured to process the digital signals and generate a mapping of the neural activity into a person's behavior, a person's mood, a person's health condition, a person's memory, or a person's intentions.