Low-chirp and enhanced-resonant frequency by direct push-pull modulation of DFB lasers

• Published in: IEEE journal of selected topics in quantum electronics 1995-06, Vol.1 (2), p.433-441
• Main Authors: Nowell, M.C., Carroll, J.E., Plumb, R.G.S., Marcenac, D.D., Robertson, M.J., Wickes, H., Zhang, L.M.
• Format: Article
• Language: English
• Subjects: Chirp modulation; Distributed feedback devices; Fiber lasers; Laser feedback; Optical fiber devices; Pulse measurements; Pulse modulation; Resonant frequency; Shape measurement; Time measurement
• ISSN: 1077-260X; 1558-4542
• DOI: 10.1109/2944.401226

The first long haul experiment on the use of a new direct modulation scheme is reported. This scheme in principle permits simultaneous tailoring of the chirp and enhancement of the resonant frequency of a distributed feedback (DFB) laser. Numerical and analytical results are presented that demonstrate the properties of push-pull modulation along with supporting experiments. Measurement of the time resolved chirp shows that push-pull modulation results in a low-chirp and a unique-chirp shape, which improves pulse transmission along a dispersive fiber. Initial experiments, using a bulk active region unoptimized DFB device driven directly by push-pull modulation, demonstrate operation over 150 km transmission at a bit rate of 2.5 Gb/s with a practical system receiver giving 10/sup -9/ bit-error rate at a dispersion penalty of -0.5 dB. Significant improvements are foreseen using quantum-well material. Simulations indicate that with appropriately optimized devices and drives, direct modulation at 10 Gb/s may give transmission over 100 km of standard fiber comparable to existing externally modulated systems.< >