Accessible tuning range of direct intensity modulated three-section DBR lasers in WDM applications

Wavelength division multiplexing (WDM) applications which require a few wavelengths can utilize the distinct longitudinal modes of a distributed Bragg reflector (DBR) laser for the wavelength multiplexing and a fiber Fabry-Perot optical filter for the wavelength demultiplexing. For direct intensity modulated DBR lasers, the portion of the CW mode tuning curve which yields reliable WDM system performance is determined based on measurements of the modulated mode suppression ratio and bit error ratio. For an optical filter with a bandwidth of 54.5 GHz, the portions of the CW mode tuning curves which yield a bit error ratio less than 10^-10 vary from 0.7-0.85, depending on the particular longitudinal mode. The performance implications of the optical filter bandwidth and the influence of direct modulation on the laser spectrum are also examined