摘要:
In accordance with the invention, a tunable fiber grating comprises a fiber grating secured to a magnetostrictive body so that magnetostrictive strain will be transmitted to the grating. An electromagnet is disposed adjacent the magnetostrictive body for applying a magnetic field along the body. Control of the current applied to the electromagnet permits control of the strain transmitted to the fiber grating, and thus control of the grating spacing and reflection frequency. In a preferred embodiment the magnetostrictive body is cylinder bonded along the grating. In alternative arrangements, the magnetostrictive effect can be mechanically amplified. An add/drop multiplexer employing the tunable gratings is described.
摘要:
In accordance with the invention, a tunable fiber grating comprises a fiber grating secured between a pair of magnets so that magnetic force (repulsive or attractive) applied to the magnets is transmitted to the grating. An electromagnet is disposed adjacent the magnets for applying the field to magnetize them. Control of the current applied to the electromagnet permits control of the force transmitted to the fiber grating and, thus, control of the grating strain, spacing and reflection frequency. In a preferred embodiment the electromagnet is actuated to produce magnetic pulses which control the remanent force between the two magnets, eliminating the need for continuous power. An add/drop multiplexer employing the tunable gratings is described.
摘要:
A device and method for dynamically tuning a long-period grating of an optical fiber is disclosed. The grating is made tunable by using a controlled strain imposed on the fiber adjacent the grating, wherein the strain comprises an electromechanical force, magnetostrictive force, magnetic force, or a thermally-induced force. An improved optical communication system comprising a dynamically gain-equalized amplifier device, a wavelength feedback device, and the tunable long-period grating device is also disclosed. In the communications system, the grating device is reconfigured to have a desired broadband filtering frequency, thus equalizing the amplifier gain, in response to feedback from the wavelength detector.
摘要:
A temperature compensated optical fiber grating device comprises a longitudinally extending optical fiber grating having a length and a packaging assembly for the grating comprising a first longitudinally extending body of material having a first coefficient of thermal expansion (CTE) and second and third longitudinally extending bodies of material having CTE's lower than the first CTE. The three bodies are mechanically attached at alternate ends to form a composite structure having an effective negative CTE between two ends to which the grating is attached. The resulting grating device can be made in compact form having an overall length less than 30% more than the grating (and preferably less than 10%) and can reduce the temperature dependent wavelength change in the grating to less than 0.2 nm/100.degree. C. and preferably less than 0.05 nm/100.degree. C. In a preferred embodiment, the packaging bodies include a cylinder enclosing the grating.
摘要:
A tunable fiber grating comprises a temperature-sensitive body secured to a fiber having a fiber grating region for transmitting thermally-induced strain to the grating. The amount of strain and hence the degree of wavelength tuning are controlled by adjusting the temperature of the temperature-sensitive body, wherein the extent of adjustment is preferably pre-determined according to feedback from a wavelength detector. Large thermal strains obtainable with the present invention allow a wide range of wavelength tuning with a relatively small and convenient temperature change near ambient temperature. In a preferred embodiment, the temperature-sensitive body is cylindrical and comprised of a nickel-titanium alloy bonded to the grating. In alternative arrangements, the thermal strain effect can be amplified. An add/drop multiplexer employing the tunable gratings is also described.
摘要:
This invention includes field emitters, in particular, electron field emitters with metal oxide nanoscale, aligned and sharped-tip emitter structures, the metal oxide emitter structures being a plurality of carbon nanostructures supported by and projecting from a substrate and including a metal oxide coating overlying the surfaces of the plurality of carbon nanostructures.
摘要:
Techniques, apparatus, materials and systems are described for providing solar cells. In one aspect, an apparatus includes a high efficiency dye sensitized solar cell (DSSC). The DSSC includes three-dimensional nanostructured electrodes. The three-dimensional nanostructured electrodes can include a cathode; an electrolyte; and anode that includes TiO2 nanotubes arranged in a three-dimensional structure; and a photosensitive dye coated on the anode.
摘要:
Systems, techniques and applications for nanoscale coating structures and materials that are superhydrophobic with a water contact angle greater than about 140° or 160° and/or superoleophobic with an oil contact angle greater than about 140° or 160°. The nanostructured coatings can include Si or metallic, ceramic or polymeric nanowires that may have a re-entrant or mushroom-like tip geometry. The nanowired coatings can be used in various self-cleaning applications ranging from glass windows for high-rise buildings and non-wash automobiles to pipeline inner surface coatings and surface coatings for biomedical implants.
摘要:
This invention discloses novel nanocomposite material structures which are strong, highly conductive, and fatigue-resistant. It also discloses novel fabrication techniques to obtain such structures. The new nanocomposite materials comprise a high-conductivity base metal, such as copper, incorporating high-conductivity dispersoid particles that simultaneously minimize field enhancements, maintain good thermal conductivity, and enhance mechanical strength. The use of metal nanoparticles with electrical conductivity comparable to that of the base automatically removes the regions of higher RF field and enhanced current density. Additionally, conductive nanoparticles will reduce the surface's sensitivity to arc or sputtering damage. If the surface is sputtered away to uncover the nanoparticles, their properties will not be dramatically different from the base surface. Most importantly, the secondary electron emission coefficients of all materials in the nanocomposite are small and close to unity, whereas the previously used insulating particles can produce significant and undesirable electron multiplication.
摘要:
A mechanically stable and oriented scanning probe tip comprising a carbon nanotube having a base with gradually decreasing diameter, with a sharp tip at the probe tip. Such a tip or an array of tips is produced by depositing a catalyst metal film on a substrate (10 & 12 in FIG. 1(a)), depositing a carbon dot (14 in FIG. 1(b)) on the catalyst metal film, etching away the catalyst metal film (FIG. 1(c)) not masked by the carbon dot, removing the carbon dot from the catalyst metal film to expose the catalyst metal film (FIG. 1(d)), and growing a carbon nanotube probe tip on the catalyst film (16 in FIG. 1(e)). The carbon probe tips can be straight, angled, or sharply bent and have various technical applications.