All-Optical Device Switches Signal Wavelength
Researchers at the University of California, Santa Barbara, have developed what they call a "tunable photon copier," an integrated device that receives an input signal at one wavelength and converts it to another. The 0.5 x 3-mm indium phosphide device incorporates an input amplifier, a tunable distributed Bragg reflector laser and a Mach-Zehnder interferometer to shift a 1550-nm signal wavelength by up to 27 nm.
Wavelength conversion is needed in optical communications networks to fit the optimum number of signals in each leg of the fiber backbone. Signal regeneration in current networks uses electronic detection, amplification and switching. The new, single-chip device, developed in Daniel J. Blumenthal's lab, offers all-optical signal regeneration and wavelength conversion, and it avoids the noise associated with switching from photons to electrons and back.
Blumenthal believes that the wavelength converter will offer advantages in power dissipation and scaling for optical networks, and that it may be the first of many such devices. "Photonic integration is ready to take off," he said, "and over the next five years, major advances in the number of devices and functions per chip will change the functional performance and economic operating point for this technology."
- mach-zehnder interferometer
- Derived from the Twyman-Green interferometer, the Mach Zehnder is an amplitude splitting interferometer that consists of two beamsplitters and two fully reflecting mirrors. Light from an extended source passes through the first beamsplitter resulting in two lightwaves traversing equal and separate optical paths. The two paths are later recombined with a set of mirrors at a second beamsplitter in which the resultant beam is then passed to an observation plane where interference fringes are...
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