Polarization Rotator Puts New Spin on Fiber Bottlenecks

Researchers at AT&T Labs of Red Bank, N.J., have demonstrated a free-space micromachined polarization rotator that they believe could solve speed limitations caused by polarization mode dispersion in vintage fiber networks. At the Optical Fiber Communications Conference in Baltimore, they proposed that a combination of these devices could remove polarization-mode-dispersion-related speed bottlenecks in long-haul communications networks.

The polarization rotator comprises four movable micromirrors, two partially reflecting and two completely reflecting, on a 5-mm² silicon chip. Integrated microactuators control the mirrors, which are the width of a human hair, to alter the phase and thus the polarization of the signal. The devices can be fabricated in batches with standard photolithography techniques.