Feb 23 2008
Infinera is today announcing the results of two lab demonstrations with significant implications for the future development path of photonic integration and high-capacity optical networks.
In the first demonstration, Infinera successfully developed and tested a photonic integrated circuit (PIC) that integrates ten wavelengths of data at 40 Gigabits/second (Gb/s) per wavelength, using Differential Quadrature Phase-Shift Keying (DQPSK) modulation, for an aggregate data rate of 400 Gb/s. The implementation of DQPSK modulators on an Infinera PIC will enable the commercial production of the next generation of PICs, with a capacity per chip of 400 Gb/s. This PIC integrates more than 100 optical devices on a single chip, more than double that of today's 100 Gb/s PIC.
DQPSK modulation is an advantageous scheme for increasing the data rate on each DWDM channel as it offers high spectral efficiency, high tolerance to impairments including dispersion, and superior optical signal-to-noise tolerance, thereby maximizing optical reach.
"This implementation of a 400 Gb/s PIC using 10 sets of Mach-Zehnder modulators at 40 Gb/s achieves performance similar to discrete implementations of 40G DQPSK," said Fred Kish, Infinera Vice President, Development and Manufacturing. ."But the use of photonic integration to integrate dozens of optical devices into a single package dramatically scales the capacity per chip while simplifying the design and manufacture of the part, and has the potential to deliver significant improvements in the areas of cost, power consumption, and reliability," Dr. Kish added.
SOAs to Address Full Fiber Spectrum
In the second lab demonstration, Infinera demonstrated successful transmission of data with a 100 Gb/s PIC using on-chip semiconductor amplifiers (SOAs) in the S-band over a distance of 320 kilometers. Today's DWDM networks are limited by EDFA (erbium-doped fiber amplifier) technology, which can only amplify effectively over a very limited range of the optical spectrum. Known as the C-band, this range accounts for just 4.4 TeraHertz (THz), out of a full fiber spectrum of 55 THz. Amplification by SOAs can allow transmission in spectral regions inaccessible in systems reliant upon EDFA amplification, opening up the full fiber spectrum for data transmission. In this demonstration, a ten-channel PIC with integrated SOAs successfully transmitted error-free data in the 1490 nanometer range of the S-band without external dispersion compensation.
"Opening up the full potential fiber bandwidth into spectral regions inaccessible with EDFAs is a significant innovation for optical networks," commented Infinera director of optical systems Steve Grubb. "Photonic integrated circuits enable cost-effective use of SOAs and thus offer the possibility of scaling optical networks across the full fiber spectrum. As we look for ways to economically scale network capacity to respond to increased demand from IP traffic, this significantly expands the current WDM tool kit."