What does CD stand for?

Byline: datta03 3S PHOTONICS, world-leading French manufacturer of optical and optoelectronic components for telecommunications networks, recently announced that a prototype of its 1915 LMA Series of Next-Generation directly modulated 1550nm high bandwidth analog laser modules introduced at ECOC in September has been successfully tested at 19Gbit/s over 25km of single mode fiber without any chromatic dispersion compensation, and using OFDM modulation format.

At 10 Gbps ZR applications, DMLs were not a reliable light source because transmission distance was limited by chromatic dispersion due to optical spectrum chirping.

The attributes of these fibers are optimized for reduced macrobend loss for bends as small as 10 mm radius, while their specifications for attenuation, chromatic dispersion and PMD remain the same as those specified in G.

The CL1012 IC delivers the known benefits of MLSE - improved tolerance to chromatic dispersion (CD), polarization mode dispersion (PMD) and nonlinear distortion, impairments that are prevalent in telecom networks - in a 10x10 mm(2) package that dissipates less than 2 watts of power, thereby enabling these benefits for the first time in a small form factor 300 pin transponder.

Concerning chromatic dispersion, NIST has developed two systems to measure relative group delay which broadens pulses and limits the system data rate.

As data rates increase to 40G and beyond, however, chromatic dispersion and, even more important, polarization-mode dispersion (PMD) limit the distance over which the data can be transmitted.

Important topics this year were dispersion measurements, both polarization dispersion and chromatic dispersion, and nonlinear optical measurements.

Since transmission distance is less than 10km, power penalty due to chromatic dispersion can be negligible, so competitive direct modulation can be used for this CWDM SFP+ module.