The high-speed limit of FM response in semiconductor lasers

The high-speed frequency modulation (FM) response has been investigated through rate equation analysis. The intrinsic limit of FM response has been found to be given by the product of FM efficiency, eta /sub FM/, and the FM bandwidth, B. This relation shows that a wide FM bandwidth means a small FM efficiency. Although the FM efficiency changes with the differential gain or the nonlinear gain coefficient, eta /sub FM/B is almost constant. The value of eta /sub FM/B was about 5 GHz/sup 2//mA for 1.5- mu m InGaAsP/InP lasers with 300- mu m cavity length. This limit has been confirmed experimentally.>