Tunable amplification properties of distributed feedback laser diodes

The tunable amplification properties of a distributed feedback laser diode (DFB-LD) are described. The performance of the laser diode as an optical filter, its tuning range, amplification gain, crosstalk due to submodes, and signal-to-noise ratio are determined. To achieve maximum amplification with the least noise, the DFB-LD injection current is held at or near the threshold value by feedback from an optical detector. The resonant wavelength is precisely controlled over a range of 2.0 nm (154 GHz) by varying the temperature of the DFB-LD, while at the same time the injection current is kept at the optimum value by the feedback system. By using the tunable amplification properties of a DFB-LD, an optical tunable filter was experimentally observed.<
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