Digital transmission with intracavity loss modulated quantum well distributed feedback lasers

The authors compare the modulation and spectral characteristics of a conventional current modulated multiple quantum well (MQW) distributed feedback (DFB) laser and a voltage controlled, intracavity loss modulated (ICLM) MQW DFB laser. They show that the leading edge of optical pulses from digitally modulated ICLM lasers also has an associated blue-shift but that the trailing edge, however, has virtually no spectral shift. Pulses with these spectral characteristics will degrade system performance only when the span length is such that the leading edge has propagated through the dead time due to the laser turn-on delay. Only beyond that span will a dispersion penalty appear. A comparison is made between temporal profiles and time resolved optical spectra of regular injection current modulation and intracavity loss modulation. The authors illustrate the results by demonstrating penalty free digital transmission at a 1.7 Gb/s/sup -1/ data rate over a 36 km span of single-mode optical fiber.<
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