A development team at Infinera Corp. in Sunnyvale, Calif., has achieved a record one trillion bits per second (1 terabit/s) speed on a single integrated indium phosphide chip. Infinera staff pioneered the design and manufacture of photonic integrated circuits (PICs) aimed at helping telecommunications companies expand the capacities of networks while adapting to new, more efficient, data-handling technologies.
“Traditional transponder-based system architectures are inflexible, and costly and time-consuming to upgrade,” says Dr. Radhakrishnan Nagarajan, research fellow at Infinera and a senior member of Infinera’s PIC development team. “Our PIC approach enables us to make optical networks more powerful, flexible and reliable than ever before using equipment that is significantly smaller, less expensive, and uses much less energy.”
Infinera’s latest PIC is at the core of a new 10-channel receiver, with each channel operating at 100 Gbit/s data rates. It contains more than 150 optical components—such as frequency tunable local oscillator (LO) lasers, devices for mixing the LO and incoming signals, variable optical attenuators for LO power control, a spectral demultiplexer to separate the individual wavelength channels, and 40 balanced photodetector (receiver/transmitter) pairs—all integrated onto a chip smaller than a fingernail.
The key technical advance operating behind 100-Gbit/s-per-channel technology is the ability to detect incoming data encoded using the optical industry's most spectrally efficient modulation technique, called polarization multiplexed Quadrature Phase-Shift Keying, or PM-QPSK.
“Just as important as a transmitter’s clever and efficient encoding method is a fast and reliable way for the receiver to convert the information back to its original form,” explains Dr. Nagarajan. “For PM-QPSK, we designed and integrated narrow-linewidth lasers that detect the phase encoded data very efficiently.”
Infinera expects PICs with a capability of a terabit or more to be available commercially within a few years. The company has announced that a 500-Gbit/s PIC will be available in 2012.
“In many ways, PIC-based optical networks are starting to take on the intelligent features of routed (IP) networks, like the ability to reroute traffic in the event of a break in the fiber—but at a fraction of the cost and power consumption,” Dr. Nagarajan adds.
Dr. Nagarajan’s presentation at OFC/NFOEC, titled “10-channel, 100Gbit/sec per channel dual polarization coherent QPSK, monolithic InP receiver photonic integrated circuit,” will take place Monday, March 7 at 3:15 p.m. in the Los Angeles Convention Center.