An HOE demultiplexer has been fabricated on a new holographic film, at 633nm. Our previous effort used dichromated gelatin, and was tested in the visible. Experiment results are presented showing performance at wavelengths of between 820 and 860nm. The results give a focused spot size of 150um and a diffraction efficiency (uncorrected) of 40%. The HOE demultiplexer is a single element thin film device that both disperses and focuses the light.

The widespread use of fiber optic couplers has been significantly inhibited by their high cost. This paper presents a review of three generic types of fiber optic couplers, concentrating on their manufacturability. It is this ease of manufacture that ultimately determines the coupler cost and availability in large quantity. Fused biconical taper couplers prove to be quite versatile with excellent optical characteristics but less adaptable to mass production. A detector/tap coupler is described that has much improved manufacturability and includes a detector in the coupler itself, thereby saving connector costs. Finally, an active bidirectional coupler is discussed that incorporates a source and detector in the coupler body, thereby eliminating the need for all external device connections. This compact and rugged device is easily manufactured in large quantity while at the same time having excellent optical characteristics.

For LAN systems using a loop or ring topology, two types of directional couplers are required for signal transfer between fibers-eauiport and tapoff. The former divides light equally into its output ports, while a tapoff coupler divides light asymetrically into its output ports. In a system where fiber splicing, connectors, and serialized {daisy-chained) couplers play a significant role, the type of couplers utilized before and after these optical components determines the system performance. Figure 1 illustrates a ring data bus employing a three port tapoff coupler and a four port directional coupler. Two technologies are used to perform the reauired couplingfused hiconical taper and expanded beam. Key optical coupler parameters affecting system performance are fiber to fiber compatibility, output port power uniformity, output port model distribution, and environmental ruggedness. An expanded beam directional coupler is the preferred choice when these parameters are important. This presentation will focus on the optical roperties and performance for three port and four port euuiport and tapoff directional couplers utilizing GRIN microlenses.

First of all we will recall briefly the conventionnal architectures of buses ( tee or linear, ring and star network ) and their limits, then the distributed star configuration and finally we present a completely new topology of a non-processed fiber optic data bus. The non-processing consist of suppressing the entire command and address part of the bus.

This paper examines key network requirements for the elements of distributed tactical command and control system. System concepts are evolved that support implementation solutions with emphasis on advanced technologies. Mobile command and control elements of ground and air forces are becoming more vulnerable in an ever increasing threat environment. This vulnerability is caused by the employment of these elements in a manner characterized by functional and physical centralization. A command and control unit typically consists of a centralized operations center surrounded by closely clustered communications and surveillance equipments. Because these elements have different deployment and employment requirements, the command and control unit is not optimized in terms of survivability, mobility, effectiveness, and operational flexibility. In recent years, convincing arguments have been put forth to the effect that distributed operations centers, redundantly structured communication functions, and netted surveillance systems can provide the necessary attributes to be effective in the advanced threat environment. Current technology does not meet the requirements of such a system. A local area network provides a power interconnection mechanism for the distributed elements of the command and control system. The requirements are for a rapid, efficient, and reliable means of transferring voice and data communications between elements. The topology of such a network must primarily consider survivability and reliability of communications interchanges with special emphasis on continued operations under degraded conditions. When such conditions occur, e.g., the result of combat attrition, a complete command and control capability should remain even though it may be at somewhat of a reduced capacity. The interconnection medium for the local area network should be immune to external disruptions, e.g., EMI, EMP, or C³CM, and should have a wide transmission bandwidth with a minimum propagation delay. This logically suggests a fiber optics medium. A universal fiber optics interface device is, therefore, required to provide access to a wide variety of users. Such a device must feature a number of advanced fiber optic technologies to make possible a flexible, survivable, high speed bus medium. (This bus is envisioned to be a synchronous time division multiplexed bus.) Based on tradeoffs between the operational and network requirements, the performance of the fiber optical local area network can be assessed.

A future Space Station will require information network architectures and technologies that are evolvable, adaptive, high performing, and self-correcting and repairing. One of the conceptual network configurations involves fiber optic data buses with Wavelength Division Multiplexing (WDM). Discussion of this network concept, components being developed and results on a four-channel WDM star bus will be presented.

A fiber optic local network is described which has been designed for use with low-cost personal computers. This network, 64NET, provides users with all the advantages of fiber optic transmission in a cost-effective package. The system was analyzed for throughput efficiency and found to be almost as efficient as a point-to-point asynchronous transmission link.