Fiber optic cables for undersea communications

Abstract

Areas for potential use of low-loss optical fibers in undersea communications are discussed, along with constraints that should be satisfied in incorporating these fibers into practical cables. Recent progress in construction of optical cable units with low attenuation, small diameter, low specific gravity, high tensile strength, and extended flexural endurance is described. Design concepts for six undersea optical cables, with a variety of diameters and capabilities, are presented in detail. Guidelines are discussed for the design of such cables. Related operational requirements on the cable, such as power transfer, are examined to show how unconventional approaches can allow advantages of the optical data link to be more fully utilized.     

Fiber optic aerial cables

While conventional cable elements can tolerate strains on the order of 1%, optical fibers cannot. As aerial cables may suffer contraction and elongation from low temperatures and high ice or wind loads, or high temperatures, respectively, proper designs have to provide the cables with length margins within which the fibers are protected against mechanical loads, except for a very limited bending stress. The well-suited loose tube buffer design, the way of calculation, and a list of reference cable plants are presented.     

Fiber optic aerial cables

While conventional cable elements can tolerate strains on the order of 1%, optical fibers cannot. As aerial cables may suffer contraction and elongation from low temperatures and high ice or wind loads, or high temperatures, respectively, proper designs have to provide the cables with length margins within which the fibers are protected against mechanical loads, except for a very limited bending stress. The well-suited loose tube buffer design, the way of calculation, and a list of reference cable plants are presented.     

Fiber optic bundle array wide field-of-view optical receiver for free space optical communications

We propose a design for a free space optical communications (FSOC) receiver terminal that offers an improved field of view (FOV) in comparison to conventional FSOC receivers. The design utilizes a microlens to couple the incident optical signal into an individual fiber in a bundle routed to remote optical detectors. Each fiber in the bundle collects power from a solid angle of space; utilizing multiple fibers enhances the total FOV of the receiver over typical single-fiber designs. The microlens-to-fiber-bundle design is scalable and modular and can be replicated in an array to increase aperture size. The microlens is moved laterally with a piezoelectric transducer to optimize power coupling into a given fiber core in the bundle as the source appears to move due to relative motion between the transmitter and receiver. The optimum position of the lens array is determined via a feedback loop whose input is derived from a position sensing detector behind another lens. Light coupled into like fibers in each array cell is optically combined (in fiber) before illuminating discrete detectors.     

Injection laser sources for fiber optic communications

This paper describes some of the laser designs and GaAs and GaAlAs epitaxial and wafer-processing technology currently used in the fabrication of laser diodes intended for incorporation into fiber optic communication or data link systems. Two classes of laser diodes are described: cw laser diodes emitting up to 75 mW and devices emitting in excess of 200 mW peak pulsed power at 27°C at duty cycles up to 10%. The fabrication and assembly of these devices is presented in detail, and the problems encountered in the transfer of these processes from a research environment to a manufacturing operation are discussed. Data are presented showing laser-emitted power, both pulsed and continuous, the angular distribution of emitted power, emission wavelength and bandwidth, optical coupling efficiency to various fibers, and laser lifetimes. In addition, the interaction between laser threshold current density, thermal impedance, emitted beam distribution, and fiber optic coupling is described. Several fiber optic laser coupling schemes are described. Finally, the results of testing pulsed laser diodes to see if they meet military environmental and performance test requirements are described with specific data presented showing the value of burn-in testing to eliminate lasers that exhibit abnormally short lifetimes from test lots.     

Injection laser sources for fiber optic communications

Abstract

This paper describes some of the laser designs and GaAs and GaAlAs epitaxial and wafer-processing technology currently used in the fabrication of laser diodes intended for incorporation into fiber optic communication or data link systems. Two classes of laser diodes are described: cw laser diodes emitting up to 75 mW and devices emitting in excess of 200 mW peak pulsed power at 27°C at duty cycles up to 10%. The fabrication and assembly of these devices is presented in detail, and the problems encountered in the transfer of these processes from a research environment to a manufacturing operation are discussed. Data are presented showing laser-emitted power, both pulsed and continuous, the angular distribution of emitted power, emission wavelength and bandwidth, optical coupling efficiency to various fibers, and laser lifetimes. In addition, the interaction between laser threshold current density, thermal impedance, emitted beam distribution, and fiber optic coupling is described. Several fiber optic laser coupling schemes are described. Finally, the results of testing pulsed laser diodes to see if they meet military environmental and performance test requirements are described with specific data presented showing the value of burn-in testing to eliminate lasers that exhibit abnormally short lifetimes from test lots.     

Fiber optical communications devices

Both low attenuation silica optical fibers with peak transmission in the wavelength regions of 0.85 μm, and 1.05 μm, and improved lasers at both wavelengths are now available. In this review paper, the principal components for emission, modulation and detection are described. The characteristics of both semiconductor lasers, made of GaAs and related compounds, emitting at 0.85 μm or 1.05 μm and high neodymium-content lasers are discussed. For modulation, current modulation of GaAs lasers and external electro-optic modulation are considered. Concerning detection, the realisation of Si photodetectors suitable at 0.85 μm and the new photodetectors at 1.05 μm from Ga_1−x In _x As are reviewed.     

Fiber optic data busses for aircraft

Abstract

A variety of fiber optic data busses is being developed for aircraft applications. This article addresses five different data busses under consideration for both military and commercial aircraft. The impact of data bus protocol on component design, the effect of data bus topology on power budget and installation issues, and overall data bus performance are discussed.     

Fiber optic data busses for aircraft

A variety of fiber optic data busses is being developed for aircraft applications. This article addresses five different data busses under consideration for both military and commercial aircraft. The impact of data bus protocol on component design, the effect of data bus topology on power budget and installation issues, and overall data bus performance are discussed.     

Fiber transmission of antisqueezed light for secure communications

Secure communications are a prospective application of the technologies originating from quantum information physics. Antisqueezed light, which is not necessarily in a quantum state, is a candidate for secure optical communications because it is tolerant to loss and amplification. We transmitted antisqueezed light, generated with a reflection-type fiber interferometer, through 100 km dispersion-shifted fibers including two erbium-doped fiber amplifiers for the first time. The coding was pseudo-randomized phase-shift keying, and the combination of the pseudo-randomization and antisqueezed fluctuations increased the bit-error rate of eavesdroppers, suggesting that our system is a technological candidate for future secure optical communications.     

Fiber optic beam delivery for endoscropic holography

Fiber optic methods to deliver the object and reference beams in endoholography are described. Two novel approaches are introduced, and quantitatively compared along with two other methods, on the basis of stability, power efficiency, and maximum power density. A method utilizing a three-layer coaxial fiber structure is shown to be most promising. Preliminary holograms have been obtained with a commercial single-mode fiber, the object beam being coupled out of the cladding by a bend in index-matching liquid.     

光纤声传感器研究

基于光纤的弯曲损耗原理,设计了一种新颖的光强度调制型声波传感器。与同类光纤声传感器相比,有更高的声光转换效率。     

Worldwide business opportunities in fiber optic communications

The world market for fiber optic intelligence transmission systems is forecast through I990 and segmented according to the geographical regions of production and demand. The total world market forecast is also segmented according to end-industry application. Fiber optic component markets are forecast and price trends are reviewed. The most significant future developments in components are discussed. The major business opportunities are outlined and the possible threats to development of a viable market are reviewed.     

Worldwide business opportunities in fiber optic communications

Abstract

The world market for fiber optic intelligence transmission systems is forecast through I990 and segmented according to the geographical regions of production and demand. The total world market forecast is also segmented according to end-industry application. Fiber optic component markets are forecast and price trends are reviewed. The most significant future developments in components are discussed. The major business opportunities are outlined and the possible threats to development of a viable market are reviewed.     

Fiber optic transversal filters for RF direction finding

A wide-band electro-optic direction-finding (DF) processor employing a network of fiber optic delay lines is described. This DF filter offers a potential instantaneous bandwidth of 20 GHz and allows for multiple, simultaneous beam-angular responses with peaks that are independent of frequency. Preliminary results of an eight-laser feasibility test model DF device with two transversal filters show good agreement between predicted and measured angular responses. This experimental matched-delay filter operates in the 200-1,000 MHz frequency range and can simultaneously monitor two angles of arrival. The laboratory results obtained in this investigation suggest that the fiber optics matched-delay filter can be useful for wide-band direction finding.     

Fiber optic transversal filters for RF direction finding

A wide-band electro-optic direction-finding (DF) processor employing a network of fiber optic delay lines is described. This DF filter offers a potential instantaneous bandwidth of 20 GHz and allows for multiple, simultaneous beam-angular responses with peaks that are independent of frequency. Preliminary results of an eight-laser feasibility test model DF device with two transversal filters show good agreement between predicted and measured angular responses. This experimental matched-delay filter operates in the 200–1,000 MHz frequency range and can simultaneously monitor two angles of arrival. The laboratory results obtained in this investigation suggest that the fiber optics matched-delay filter can be useful for wide-band direction finding.     

Fiber optic sensor interface standardization

The need for a new avionic interconnection scheme that can provide superior performance, installability and maintainability as compared with copper has become evident. Fiber optics, which has been proposed for this role, is expected to improve environmental immunity, decrease system weight, and increase bandwidth. It has also been suggested that sensors based on fiber optics can offer significant advantages in aerospace applications. Realizing these advantages is a difficult challenge because mature sensing technologies have done a good job at reasonable cost. Furthermore, it has been demonstrated that a wide variety of aircraft electrical sensors can be addressed by a few standard interfaces. Therefore, future fiber optic sensor suites will also need to be interrogated through only a few standard interfaces, and standardization of the fiber optic sensor interface will be a primary issue in furthering fiber optic sensing technology for aerospace applications. This paper discusses the fiber optic sensor standardization process underway in the Avionic Systems Division of the Society of Automotive Engineers.     

Fiber optic networks: New opportunities for rights-of-way owners

Numerous railroads, pipelines, and other utilities are presently considering the use of their rights-of-way for fiber optics communications. This article identifies the multiple methods through which a utility may structure a communications fiber optics venture and the resulting federal and state regulatory implications for each option.     

Fiber optic networks: New opportunities for rights-of-way owners

Numerous railroads, pipelines, and other utilities are presently considering the use of their rights-of-way for fiber optics communications. This article identifies the multiple methods through which a utility may structure a communications fiber optics venture and the resulting federal and state regulatory implications for each option.     

Origin of temperature dependence of microbending attenuation in fiber optic cables

Abstract

Temperature-induced changes in the attenuation of multimode optical fiber cables are shown to be caused by mismatch between the thermal expansion coefficients of the fiber and the cabling materials. A quantitative theoretical model of low temperature loss, based on the formation of fiber microbends by microvariations in the jacket concentricity, is described. This model applies to tightly jacketed, soft buffered cable designs. An equation relating the low temperature optical attenuation to cable parameters is derived using this model. Good agreement is obtained between this theoretical prediction and experimental results. The theoretical model is used to compare the effectiveness of different cable designs on reducing excess loss at low temperature.