High Resolution Optical Spectrum Analyzer for Optical System Link Quality Monitoring
Project Award Date: 06-01-1999
Increasing bandwidth in optical networks brings both greater system capacity and the challenge to carry that capacity at good quality over long distances. This increasing stress on quality has put greater importance on optical network management. The need for consistent quality monitoring, however, comes at a time when the networks themselves are more complex and more difficult to manage.
To check the quality of an optical transmission system, traditional electronic domain performance monitoring needs opto-electronic conversion for each individual wavelength channel.
For WDM (wavelength division multiplexed) optical networks with a large number of wavelength channels, optical domain performance monitoring is more efficient and cost effective compared to its electronic domain counterpart. An optical spectrum analyzer is more efficient because it can scan through all the wavelength channels simultaneously and save carriers both time and money.
But when it comes to checking a channel's modulation and data rate, most analysis systems cannot distinguish frequency components within a resolution bandwidth of 10 GHz, so they are unable to see the modulation performance and data rate of optical signal.
During this yearlong project, the team investigated various ways to build an ultra high-resolution, optical spectrum analyzer that had good resolution, wide spectrum range and compact size. Conventional optical spectrum analyzers that use defraction gratings may have wide spectrum range, but they have relatively poor resolution or big size. To achieve good spectral resolution, wide optical bandwidth and can potentially be packed into a circuit card, Hui combined the excellent spectral resolution of Febry-Perot interferometer and the wide bandwidth of thin film WDM optical demultiplexers.
Hui sees a good commercial application to the analyzer developed at ITTC. His team made the analyzer box both smaller and significantly cheaper than other systems, and it will fit into the transmission system rack.
Faculty Investigator(s): Rongqing Hui (PI)
Primary Sponsor(s): Nortel Networks