Fiber optics in avionics: Upward bound

Caren B. Les, caren.les@photonics.com

The total market for fiber optics in military and commercial aircraft, estimated at $306 million in 2009, is expected to reach $703 million in 2013, according to a report from Information Gatekeepers Inc. (IGI) of Boston. Titled Market for Fiber Optics in Military and Aerospace Avionic Systems, the document covers fighter and transport aircraft as well as unmanned aircraft systems.

One of the reasons for the now greater acceptance of fiber optic components, systems and subsystems in the two markets is that the technology has met with overall approval in the telecommunications field, the company said. The natural characteristics of fiber optics may also meet the continuing need on aircraft for more bandwidth and for wiring infrastructure with smaller size, lower weight and lower power consumption.

Unmanned aircraft systems such as the ScanEagle, shown in maritime launch, are a fast-growing military market for fiber optics. Courtesy of Insitu Inc. of Bingen, Wash.

Fiber optic cable has many advantages over copper cable, according to the Web site of Timbercon Inc., a manufacturer of fiber optic products. It transmits data over long distances much faster than copper does, and it has a smaller diameter and weighs less. Fiber optics are immune to radio frequency and electromagnetic interference, which makes them suitable for applications where proximity to electronic devices can cause these disruptions.

“Fiber optic cable uses less power and provides security and large bandwidth for data and video, according to John Lee, vice president of sales and marketing at Timbercon. It can be used on unmanned aircraft systems as well as on the ground for supporting the transfer of large amounts of data in the form of video images, he added.

Unmanned aircraft systems

Unmanned aircraft systems are perhaps the fastest-growing military market for fiber optics, according to IGI. The US military unmanned aircraft systems market is projected to generate $62 billion over the period from 2010 to 2015 with a compound annual growth rate of 10 percent, according to a report from Market Research Media of San Francisco.

“Fly-by-light [flight control based on a fiber optic infrastructure] has been discussed for years but will become a reality primarily due to the experience with unmanned aircraft systems. As commercial communication/network systems move to totally fiber-based systems, the military will have to move to these systems, and copper will be a thing of the past,” Lee said. “Multifiber and mechanical transfer pull-off connector technology has been used on major fighter systems and will become the norm rather than circular low-density “military” connectors such as 38999 or 28876. The cost is less and the weight lower, and the density is significantly higher,” he added.

Commercial aircraft

An equally large market for fiber optics is developing in large commercial aircraft, regional and private jets, helicopters and a variety of small aircraft, IGI reports. The complete infrastructure of installation, maintenance and retrofits has yet to be developed by the major carriers for fiber optics, the company indicated. It noted that, while many commercial aircraft needs can be met through military technology, requirements such as in-flight entertainment systems and “electronic flight bags” containing manuals and other applications for pilots, will have to be developed at a much lower cost than for military and aerospace systems.

Defense

Specific military and aerospace requirements present barriers to using fiber optics, however. Among them are the lack of commercial off-the-shelf components; hardened components for harsh environments; test and maintenance procedures; and low-cost, easy-to-use test and measurement equipment. Continued research is needed as well – in integrated optical components, manufacturing technology and the establishment of standards.

The market for fiber optic test and measurement equipment for avionic systems is still in development, according to IGI. The equipment developed for the telecommunications field, mostly single-mode, is being used in the military and aerospace sectors, where the majority of systems are multimode – with mixed results, the company noted.

“The most significant issues for fiber optics in military avionics involve training and cleaning: The warfighter is just not well-trained to use fiber optic cables as opposed to copper cables, and the importance of cleaning has not been impressed on those that have to use the cables,” said Lee, of Timbercon. He added, “As with all products, quality and lead time are some of the most important issues for ‘war-fighter’ applications. In harsh environment applications, the issue of high temperature, radiation hardening and exposure to ‘heavy’ vehicles can be critical design considerations.”

Applications and developments

“Some of the most important applications for fiber optics in avionics are sensing, remote communications, the connection of various information systems and IR countermeasure devices for protecting aircraft from IR homing missiles. Fiber optics are used in avionic platforms, ground-based communications and shipboard systems,” Lee said. He cited as a common example, in defense, the transfer of large amounts of data or video from an unmanned aircraft system to a satellite dish antenna and then, via fiber cable, 150 m farther to a command vehicle or tent to protect personnel from hostile fire – since there are weapons that can “home in” on the dish receiving the signal.

Lee noted that the field’s developing technology includes IR countermeasure devices, radiation-hardened fibers, high-density environmentally secure packages, Bragg grating sensors for a wide variety of applications, and connectors less susceptible to contamination. He added that technological advances that would be highly desirable for applications in avionics include bend-insensitive fiber, increased-bandwidth fibers (10 Gb and even 100 Gb), connector compatibility across various military requirements, high-power laser beam delivery, high-density interconnections and acceptance of commercial off-the-shelf components for reduction in costs where government “qualified parts list” certification may not be necessary.

Reducing costs

“The military fiber optics industry is generally controlled by a very few connector manufacturers that often attempt to fit every application into their proprietary connector technology rather than use the appropriate technology for any given application. They control the access and delivery time to their technology so that they can maintain profits and market share. The military is starting to require competitive bidding and the opening of ‘proprietary’ designs to second-source small- to medium-size companies to keep costs down and to reduce lead times. The use of commercially available technology will reduce costs to programs since the volume usage is small in most military applications as opposed to the storage, network and telecommunications industries,” Lee said.