Gain-switched picosecond pulse (<10 ps) generation from 1.3 μm InGaAsP laser diodes

Fabry-Perot-type laser diodes with high injection efficiency were found to be suitable for ultrashort pulse generation. By decreasing cavity length, the shortest pulsewidth of 6.7 ps at a repetition rate of 100 MHz was achieved under a gain switching scheme. A systematic investigation of bias-level-dependence of pulsewidth, peak output power, as well as the effect of cavity-length shortening was performed. Suppression of facet reflection of a laser diode with a normal cavity length was effective in reducing the pulsewidth (from 16.6 to 10.2 ps). It was found that the optimum condition both for minimizing pulsewidth and for maximizing peak output power can be obtained by selecting the DC bias level. The rate equation analysis also indicated that the gain compression factor may not influence the multimode lasers as much under the gain switching condition as single-mode lasers. The influence of electrical parasitics of the lasers is briefly discussed