Sabeus Photonics Inc.

Cold writing technology allows sensors to be written directly into a fiber's core without compromising its integrity, tensile strength or durability. The technique does not require stripping and recoating the fiber, and it eliminates the need for external protective packaging. The company says the mechanical strength and reliability of the gratings is improved by a factor of three compared with traditional gratings.

To develop a mass-production process for these fiber Bragg gratings, developer Sabeus Photonics Inc. of Chatsworth, Calif., had to consider the physics of light's interaction with fiber. Because standard fiber coatings are not transparent to the conventional 240-nm of UV writing radiation, the company developed a method of changing the refractive index by using 330- or 350-nm radiation.

The softer UV light penetrates buffer coatings and enables an inexpensive plastic replica phase mask to be used rather than a fused silica phase mask, making fabrication a one-step process.

Applications for sensors manufactured with this scalable process include telecommunications, in-well temperature monitoring, gas lift optimization and tube integrity detection. The technology will enable the development of land-based, down-hole and underwater sensor applications that were previously impossible.