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DP-QPSK LN modulator drives 10Gbit/s optical nets

Posted: 18 Sep 2009 ?? ?Print Version ?Bookmark and Share

Keywords:modulator? optical network? DP-QPSK technology?

P-QPSK LN modulator

Fujitsu Optical Components Ltd has introduced a compact DP-QPSK LN modulator with low drive voltage that will enable the next-generation of 100Gbit/s optical networks. The product makes it possible to construct commercial systems with high reliability, low-power consumption and superior transmission quality.

In recent years, the expansion of new services such as cloud computing and on-line streaming has brought about a dramatic increase in data communications. As the data transmission volume of communications networks rises, R&D activities related to the commercialization of next-generation 100Gbit/s optical networks have gained significant momentum. While many optical transmission signal encoding methods are under consideration, DP-QPSK transmission technology is becoming essential due to its high tolerance against signal distortions resulting from transmission fibers and relay nodes, its superior bandwidth efficiency, and its increasing transmission capacity achieved without increasing symbol rate. Moreover, this transmission technology is being standardized by Optical Internetworking Forum.

There has been growing demand for compact, low drive voltage and wide bandwidth optical modulators required for the construction of commercial optical network systems. However, achieving these capabilities has been a major challenge for DP-QPSK compatible modulators, due in part to their complicated structures.

Fujitsu Optical Components has developed the technology to overcome this challenge and has succeeded in producing a compact DP-QPSK LN modulator with low drive voltage for use in commercial optical network systems.

Compact LN modulator with DP-QPSK circuits integrated inside a single packageThe DP-QPSK modulation optical circuit and polarization beam combiner were integrated inside a single package, making the compact LN modulator suitable for 178mm x 127mm transponder.

In order to generate high-quality DP-QPSK signals, the company expanded the optical bandwidth of the modulator. To transmit DP-QPSK signal with data rate of 100Gbit/s, modulation rate of 25Gbit/s is required. By using technology similar to that employed in previously commercialized 40Gbit/s LN moderators, a wide bandwidth of 25GHz was achieved. Also, this LN modulator has low drive voltage of maximum 3.5V, making it a practical optical modulator for use in commercial systems.

In addition, by positioning multiple RF signal input terminals close to each other at one side of the modulator, DP-QPSK signals can be generated without the need to adjust for the time delay between electrical signals on the drive circuit. Also, by employing separate input terminals for the RF signals mentioned above and the DC bias signals for modulator control, the need for an external electrical circuit to combine the two types of signals was eliminated.

The DP-QPSK LN modulator will be available in December.

For application notes on modulators click here.

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