A Glimpse at Fiber Optic Sensors and Their Applications

Emilio Gonzalez, Jr.Research Analyst, Frost & Sullivan

Fiber Optic Overview

Fiber optic technology and its applications have progressed rapidly in the last 30 years. They are low cost and have the capability of carrying information from one place to another, and are immune to the many interference that afflict electrical and wireless communication mediums. This has enabled fiber optics to replace older technologies and play a key role in the fast and strong growth in worldwide communications in the last 25 years.

The replacement of older technologies to fiber optics can be attributed to the many advantages fiber optic technology offers, including:

  • Insensitive to EMI, RFI, and EMP
  • Does not radiate energy
  • Low transmission losses
  • Wide transmission bandwidth
  • Unaffected by lightning
  • Lightweight
  • Non-corrosive
  • Absolutely safe in explosive environments
  • Flexibility in upgrading
  • Immune to ground loops
  • Secure, cannot be tapped without detection

Fiber Optic Sensors

Fiber-optic sensors are a powerful class of sensors, bringing to measurement systems many of the advantages that optical-fiber technology has brought to the telecommunications industry. Three main characteristics differentiate fiber-optic sensors from other types of sensors: A) A high bandwidth of optical fibers allows them to convey a large amount of measurand information through a single fiber; B) The optical fiber is a dielectric, it is not subject to interference from electromagnetic waves that might be present in the sensing environment; and C) Fiber-optic sensors can function under adverse conditions of temperature and pressure and toxic or corrosive environments that can erode metals at a rapid rate, have little effect on optical fibers. In addition, fiber-optic sensors are intrinsically safe in explosive environments (no sparks), lightweight, compact, robust and potentially inexpensive. Therefore, useful as sensing devices for a wide range of physical and chemical applications including chemical, temperature, strain, biomedical, electrical and magnetic, rotation, vibration, displacement, pressure and flow.

Many of these categories were developed by military organizations during the past decade. These military sensors, while extremely effective at creating "smarter" structures, have not found large commercial markets, with only a few exceptions. These exceptional markets are: chemical sensing (especially in the petrochemical industry), transportation, building and structural monitoring and biomedical -- with the first three segments representing nearly all of the existing market and the fourth representing an explosive market waiting for proven, noninvasive technologies.

Figure 1 provides the revenue forecasts for fiber optic pressure sensors for North America for the years 2000-2006

In 1999, the total revenues for fiber-optic pressure sensor sales for North America totaled $14.5 million. This is approximately 5.5 percent growth from the previous year's sales of $13.7 million. It is anticipated that this trend will continue for the forecast period (2006) of this report, with growth rates accelerating from 2003 to 2006.

Fiber-optic sensors can perform the functions of virtually any conventional sensor, often faster and with greater sensitivity and they can also perform measurement tasks that would be impracticable with conventional sensors. For instance, in building and structural monitoring, fiber-optic sensors can be embedded in structures such as airplanes and bridges, continuously reporting on structural integrity and possibly averting a catastrophic failure.

Fiber Optics and Telecommunications

The telecommunications industry was primarily responsible for the development of fiber-optic sensor technology in 1980s. In spite of their special capabilities, the general acceptance of fiber optic sensors has been slow. The challenges of performance, cost, modularity and standardization all limited penetration to industrial applications. However, in the past few years, that has started to change as companies educate the public to the benefits of optical sensing in their quest for a larger part of the sensor market -- a market certainly worth pursuing. Indeed, for an indefinite period, electronic sensors, which are well supported by electronic signal-handling methods and hold established positions in control systems, are expected to coexist with fiber-optic sensors. But electronic signal-handling methods can serve fiber-optic sensors because optical signals readily convert into electronic form. And in the longer term, all-optical signal-handling methods will become available, complementing and extending the capabilities of fiber-optic sensors.

The numerous advantages of fiber-optic sensors will ensure that they continue to attract research funding for their further development. The maturation of fiber-optic technology will, over time, expand the applications of fiber-optic sensors as the cost of components such as laser sources and single-mode couplers declines and smart technology improves. Furthermore, with the drive toward automation by manufacturing facilities all over the world, the many inherent advantages of fiber-optic sensors promises a major role for them in the future.

Emerging Fiber Optic Applications

Since its discovery as a communications medium in 1966, fiber optics, transmitting or guiding light through the core of a flexible hair-thin glass strand, has become the primary interest in the telecommunications community. As demand for ever-higher bandwidth continues, researchers continue to design faster fiber-optic communications systems. Although the communications market for fiber optics of some $7 billion dominates fiber-optic applications, several non-communications applications are emerging. Among those applications are fiber-optic delivery of electric power (power by light), fly-by-light control of aircraft, fiber-optic delivery in laser welding, use of fiber optics for illumination fiber-optic sensing of parameters such as temperature, chemical constituency and strain in physical structures.

According to industry participants, fiber optic sensing technology shows that light can provide the same, if not better, response than other conventional sensing systems-sometimes many times faster and more accurate. However, many in the industry attest to the fact that being to do something and do it well does not always guarantee monetary success. Economies of scale, which relate to higher prices versus conventional techniques, and a lack of understanding among application engineers who must work with sensors everyday are some of the hurdles companies face on the road to success. Despite all this, fiber optic sensors are making inroads in hazardous-environment, environmental monitoring and other fields that will lead to further success with this technology.

Article © 1999 Frost & Sullivan

More in Operations