Infrared Fiber Optics

Infrared (IR) optical fibers may be defined as fiber optics transmitting radiation with wavelengths greater than approximately 2 μm. The first IR fibers were fabricated in the mid-1960’s from chalcogenide glasses such as arsenic trisulfide with losses in excess of 10 dB/m. During the mid-1970’s, the interest in developing an efficient and reliable IR fiber for short-haul applications increased partly in response to the need for a fiber to link broadband, long wavelength radiation to remote photodetectors in military sensor applications. In addition, there was an everincreasing need for a flexible fiber delivery system for transmitting CO2 laser radiation in surgical applications. Around 1975, a variety of IR materials and fibers were developed to meet these needs. These included the heavy metal fluoride glass (HMFG) and polycrystalline fibers as well as hollow rectangular waveguides. While none of these fibers had physical properties even approaching that of conventional silica fibers, they were, nevertheless, useful in lengths less than 2 to 3 m for a variety of IR sensor and power delivery applications.