Photonic 2R regenerator offers superior signal integrity, compactness
July 21, 2005 Ipswich, UK -- The Centre for Integrated Photonics (CIP) has introduced an all-optical photonic 2R regenerator for optical networking applications up to 40 Gbit/sec. The company says the device breaks new ground in performance and compactness. Fabricated from a hybrid integrated combination of a planar silica Mach-Zehnder interferometer (MZI) and a monolithic semiconductor optical amplifier (SOA) array, the company says its 40G-2R-ORP features extremely low intra-device excess losses thanks to its novel design and passive assembly techniques. The packaged device measures 7.2 x 3 x 1.4-cm.
The re-amplification and re-shaping device is suitable for inline regeneration in long-haul networks, for signal conditioning at network points such as add-drop nodes, and for mitigation of polarization-mode dispersion. The company says the device's intrinsic ability to perform additional functions, including wavelength conversion, greatly extends flexibility for network system developers. Optical logic functions are also achievable.
According to the company, the 40G-2R-ORP employs a combination of planar silica and indium phosphide (InP) component technologies to achieve outstanding re-amplification and re-shaping performance. The two components used are a planar single-mode waveguide with splitter/combiner elements configured to create a balanced Mach-Zehnder interferometer, and a monolithically integrated array of two non-linear semiconductor optical amplifiers. Special interface features on both components, combined with a proprietary precision alignment technique, allow the devices to be assembled without active alignment. The company says this makes the finished component highly amenable to economic volume production. The company says its hybrid integration approach allows the choice of optimized device technologies, enabling low passive waveguide losses and high optical gains. The device is also scalable through further hybrid integration, to create multi-channel devices, according to the company.
The device regenerates signals by the use of non-linear cross-phase modulation in the SOAs. Two data inputs to the device, one a time-delayed version with respect to the other, are used as switching signals for the SOAs. The temporal offset creates a gating window that switches the digital data onto a second continuous wave optical input. The non-linear MZI's response, coupled with the operating characteristics of the SOAs, provides excellent control over the amplifier output pulse shape. Simple MZI phase bias is provided by thermo-optic phase shifters.
"This device provides high quality regeneration for advanced optical networking systems," maintains Graeme Maxwell of CIP. "Its world-leading performance is complemented by a design that is not only suitable for volume manufacture, but also for versatility of application. The same device can be configured for 2R regeneration, for signal conditioning combined with wavelength conversion, for 3R regeneration with the addition of an optical clock source, or for bit-level optical switching and logic."