Alcatel Buys Fiber Filters
Innovative Fibers makes Fiber Bragg Gratings (FBGs) which act as filters, reflecting back a specific wavelength of light while allowing other wavelengths to continue on their way.
FBGs promise to play a big role in next generation DWDM systems. This is mainly because they can single out specific wavelengths more precisely than Arrayed Waveguide Gratings (AWGs), often used in current DWDM gear.
The extra precision means that wavelengths can be packed more closely together. Alcatel says it will be able to pack 160 wavelengths in a fiber using Innovative’s FBGs.
FBGs are made from fiber, which is doped with chemicals, covered with a mask and then blasted with ultra-violet light to change the refractive index of the glass in a series of microscopic stripes running across the fiber, called a grating. The spacing of the stripes determines the wavelength of light that’s reflected back.
As FBGs are made of fiber, their gratings can be longer than the gratings created in AWGs, which are made using semi-conductor technology – depositing a thin film of silica on top of silicon and then etching it. The extra length of fiber gratings adds up to more precision – not only in separating one wavelength from another but in enabling each wavelength to carry more traffic (see Fiber Components Excite VCs).
Innovative’s FBGs are also used in other optical components, notably Gain Flattening Filters. These ensure that the light power is similar in all wavelengths, a crucial issue in DWDM systems.
Innovative Fibers’ main claim to fame is that it's an established manufacturer of high quality FBGs, according to Bernard Malo, the company’s co-founder and CTO. “We have a technique that’s well established and well suited to mass production,” he says.
The area around Qebec is home to a number of startups developing Fiber Bragg Gratings, partly because they were discovered there, by Ken Hill in 1978. Innovative Fibers is the only startup in the area to have manufacturing facilities, according to Malo.
By Peter Heywood, international editor, Light Reading http://www.lightreading.com .