The invention provides a system having a broadband spectrometer with a fiber optic reformattor for field use in detecting and identifying gas clouds within a field of view. The system includes a grating type spectrometer, a fiber optic reformattor, a focal plane detector array and electronics for background signal subtraction techniques for generating spectral signature data which is analyzed for gas detection and outputting a decision making signal for recognition.

Broadband spectrometer with fiber optic reformattor

A fiber optical array with precision fiber and positioning and a process for manufacturing such an array. The position of the ends of the optical fibers depends upon placement within a target that has been lithographed using highly precise lithography similar to that used in VLSI integrated circuits. The placement of an end with its core within its target is performed with the aid of microscopes and micro-manipulators. Once an end is in the proper location, ultraviolet curable adhesive is used to permanently fix its position precisely. Arrays having positional precision to within 1 micrometer are achievable by this invention.

Optical fiber array and process of manufacture

We describe a technique for assembling fiber bundle arrays as needed in optical computing and photonic switching systems. Two 4 x 4 arrays with single-mode and multimode optical fibers were manufactured. Fiber ends were located to within 3 μm of their ideal position and to a pointing precision of 30 arcmin. A third 4 x 8 array was manufactured with single-mode fibers, and fiber ends were located to within 1.5 μm of their ideal position.

Fabrication of fiber bundle arrays for free-space photonic switching systems

The fabrication of a fused 8/spl times/8 array of multimode optical fibres is reported. The array is designed for applications requiring efficient power collection and transmission, accurate fibre placement, low cost and environmental stability. The fabrication technique can be modified to produce arrays with alternate fibre lattice configurations and core cross-sections.

Two-dimensional multimode fibre array for optical interconnects

Two-dimensional fiber optic arrays are fabricated for the input and output to a prototype 16-element optical crossbar switch. The switch input comprises a 4 x 4 square array of 125-μm-diam, polarization-preserving fibers with a 5-μm core. The interfiber spacing was 200 μm. For the output array, a larger 4 x 4 square array of 140-μm-diameter, 100-μm-core, multimode fibers was constructed. Interfiber spacing for this array was 800 μm. Correct positioning of the optical fibers was achieved using location holes. These were laser machined in polyimide for the input array and chemically etched in silicon for the output array. A supporting matrix of epoxy adhesive was used to allow polishing of the arrays. Location hole positions were generated to within ±3 μm in both substrate materials, although hole tapering is observed. The effects of hole tapering on fiber orientation have been minimized by aligning two separate hole arrays. Polarization errors for the input array are typically ±10 deg. Mean errors in fiber position for the partially polished input and output arrays were 3.6 and 6.3 μm, respectively. Positional errors can be reduced to the positioning accuracy of the location holes by further polishing of the fiber-matrix structure. Methods for further reducing positional errors in the future are discussed.

Fabrication of two-dimensional fiber optic arrays for an optical crossbar switch

Procede d'assemblage de faisceaux de fibres sous forme de reseau bidimensionnel pour alimenter un reseau de detecteurs

Fabrication and characterization of a 2-D fiber array.

This report provides a review and evaluation of rain fade measurement and compensation techniques for Ka-band satellite systems. This report includes a description of and cost estimates for performing three rain fade measurement and compensation experiments. The first experiment deals with rain fade measurement techniques while the second one covers the rain fade compensation techniques. The third experiment addresses a feedback flow control technique for the ABR service (for ATM-based traffic). The following conclusions were observed in this report; a sufficient system signal margin should be allocated for all carriers in a network, that is a fixed clear-sky margin should be typically in the range of 4-5 dB and should be more like 15 dB in the up link for moderate and heavy rain zones; to obtain a higher system margin it is desirable to combine the uplink power control technique with the technique that implements the source information rate and FEC code rate changes resulting in a 4-5 dB increase in the dynamic part of the system margin. The experiments would assess the feasibility of the fade measurements and compensation techniques, and ABR feedback control technique.

/pdf/rain-fade-compensation-for-ka-band-communications-satellites-1mpw31o42b.pdf

Brian J. Markey

Papers

Fabrication and characterization of a 2-D fiber array.

Rain Fade Compensation for Ka-Band Communications Satellites