Frequency plan and wavelength switching limits for widely tunablesemiconductor transmitters

摘要

As wavelength-division-multiplexing (WDM) channel spacingncontinues to decrease in size, and with the application of tunablenlasers in dense wavelength-division-multiplexing (DWDM) systems, wendemonstrate the ability of tunable semiconductor lasers to cope withndemanding channel spacing and inevitable low frequency setting error. Bynfinding the stable operating points of a single tunable laser at thendesired frequencies, using advanced software a lookup table to drive thenlaser was generated. Once the drive currents to access 2000 channelsnwith the laser are found, their frequency setting error and side modensuppression ratio (SMSR) were found. These results open up newnpossibilities for DWDM access networks as well as providing a limit ofnachievement for channel density in the network. Meanwhile, since thensampled-grating distributed Bragg reflector (SG-DBR) laser is among thenmost attractive sources for DWDM, it is important to investigate itsnwavelength switching characteristics. This behavior will affectnwavelength routing and the capability limits for channel reallocation innfuture networks. We present new detailed experimental studies on anhigh-speed SG-DBR laser by using a Fabry-Perot interferometer techniquenadapted for the noncontinuous wave case. Measurements of fast intramodaln(i.e., cavity mode) and intermodal (i.e., supermode) wavelengthnswitching and insights into the device's dynamic behavior are obtained.nImplications are given for transmitter design in dynamic wavelengthnrouting and channel reallocation