Abstract:
A chip-scale, reusable sensor can detect aromatic hydrocarbons, such as benzene, toluene, ethylbenzene, and xylenes (BTEX), rapidly in water without sample preparation. The device is capable of real-time, continuous monitoring for BTEX solutes, which diffuse into a film, such as a polymer, on the sensors surface. In operation, BTEX analytes concentrate in the film, causing an increase in refractive index, which modulates evanescent coupling into the chips integrated photodetector array. Integration of the photodetector array simplifies system instrumentation and permits incorporation of an on-chip photocurrent reference region in the immediate vicinity of the sensing region, reducing drift due to temperature fluctuations. In some examples, the chip responds linearly for BTEX concentrations between 1 ppm and 30 ppm, with a limit of detection of 359 ppb, 249 ppb, and 103 ppb for benzene, toluene, and xylene in water, respectively.
Abstract:
One embodiment of a single mode optical fiber includes: a graded index central core region having outer radius r 1 and relative refractive index Δ 1 ; a cladding region comprising (i) a first inner cladding region having an outer radius r 2 2 and 0.65 ≤r 1 /r 2 ≤ 1; (ii) and a second inner cladding region (i.e., trench) having an outer radius r 3 > 10 microns and comprising a minimum relative refractive index Δ 3 , wherein said second inner cladding region has at least one region with a relative refractive index delta that becomes more negative with increasing radius; and (iii) an outer cladding region surrounding the second inner cladding region and comprising relative refractive index Δ 4 , wherein Δ 1 > Δ 2 > Δ 3 , Δ 3 4 .
Abstract:
Embodiments of the present invention relate to a fiber design that achieves high nonlinearity, an effective index providing phase matching for an illustrative wavelength conversion process, and a low sensitivity to perturbations in fiber scaling. In one embodiment, a fiber comprises an inner core having an inner core radius and an inner core index, an outer core having an outer core radius and an outer core index, the outer core index being lower than the inner core index, an inner cladding, having an inner cladding radius and an inner cladding index, the inner cladding index being less than the outer core index, and an effective index of the fiber, the effective index being greater than the inner cladding index and less than the outer core index, wherein the fiber has a low perturbation sensitivity factor of dispersion to scaling less than about 20 ps/ nm / km along the length of the fiber.
Abstract:
Disclosed is an optical fiber having a core with an alkali metal oxide dopant in an peak amount greater than about 0.002 wt. % and less than about 0.1 wt. %. The alkali metal oxide concentration varies with a radius of the optical fiber. By appropriately selecting the concentration of alkali metal oxide dopant in the core and the cladding, a low loss optical fiber may be obtained. Also disclosed are several methods of making the optical fiber including the steps of forming an alkali metal oxide-doped rod, and adding additional glass to form a draw perform. Preferably, the draw preform has a final outer dimension (d2), wherein an outer dimension (dl) of the rod is less than or equal to 0.06 times the final outer dimension (d2). In a preferred embodiment, the alkali metal oxide-doped rod is inserted into the centerline hole of a preform to form an assembly.
Abstract:
An optical fibre being optically transmissive at a predetermined wavelength of light lambda and comprising a plurality of coaxial layers. Each layer having an optical path length that varies radially, the coaxial layers being arranged to give the fibre a refractive index profile which, in use, causes sufficient Fresnel diffraction of the light such that it is guided in the fibre. The refractive index of a cladding region (60) is intermittently suppressed by controlling heating of the preform tube, thus forming a chirped saw-tooth profile (70). The optical fibre may include a lens. In this case, each of the layers has an optical path length that increases gradually outwardly by substantially n x lambda /2 (n: integer).
Abstract:
Disclosed is an optical fiber which includes a core including silica with a core diameter and having at least two dopants, a maximum relative refractive index delta of at least 0.7% and an alpha value in the range of 1.9-2.2. The core has a refractive index profile configured to transmit light in a multimode propagation at a first wavelength λ 1 in the range of 800-1100 nm and to propagate light in a LPO1 mode at a second wavelength λ 2 . The second wavelength λ 2 is greater than 1200 nm. The optical fiber is structured to have a LPO1 mode field diameter in the range of 8.5-12.5 μm at 1310 nm.
Abstract:
An ultra wideband (UWB) feed circuit is provided from an optical substrate disposed over a multi-layer dielectric substrate with each layer being provided from a material having a relatively low relative dielectric constant. Conductor layers are disposed between at least a pair of the dielectric substrates which make up the multi-layer dielectric substrate. The multi-layer dielectric substrate is, in turn, disposed over a suspended air stripline (SAS) signal path comprised of a substrate having a conductor disposed thereover. The optical substrate, multi-layer dielectric substrate and SAS are disposed in a radio frequency (RF) waveguide.
Abstract:
광섬유, 광섬유 제조방법 및 광섬유를 이용한 레이저 전송방법이 제공된다. 개시된 광섬유는, 중심으로부터 반경이 커질수록 실질적으로 굴절률이 감소하는 코어부재와, 상기 코어부재를 둘러싸도록 마련되는 클래드를 포함한다. 그리고 상기 클래드는, 상기 코어부재와 상기 클래드가 만나는 코어-클래드 경계에서 상기 코어부재의 굴절률보다 높은 굴절률을 가진다. 개시된 광섬유는 고품질 고출력 레이저 빔을 전송시킬 수 있다.