Bell Labs creates optical filter chip

Bell Labs is furthering its reputation for innovation, claiming a major step toward silicon photonics. Now as Alcatel-Lucent employees, Bell Labs researchers will present a paper at the Optical Fiber Communication conference this week revealing their creation of an optical filter made of silicon.

Making integrated circuits do the work of optical components has been a dream of telecom technologists, as mass-production of optical chips would be vastly less expensive than today's components.

Passing optical signals through silicon was unthinkable a few years ago, researchers said, because imperfections in the walls of silicon would scatter photons. But ever-improving technology has finally yielded smooth enough walls, they said.

The chip Bell Labs created, a tunable equalizer for cleaning optical signals, was manufactured using complementary metal oxide semiconductor silicon (CMOS), the standard commercial method. But the chip itself won't be commercially available “for years,” said Alice White, Bell Labs' photonics director.

The researchers used commercial manufacturing — at a BEA Systems foundry — to prove such a device could enjoy the cost benefits of mass-production. And at about 10 millimeters wide, it's about 5% the size of today's components.

Chips may replace other optical components in time, but the introduction of any silicon photonics would start to bring costs down. White compared the idea to a hybrid car that alternates between gas and battery power. More silicon optics also means fewer optical-electrical conversions, another industry holy grail.

Imagine, White said, fiber-to-the-home (FTTH) networks in which boxes outside the home no longer contain photonic components-a large expense in FTTH networks. “Imagine if, instead, there was just a silicon chip.”