Damping-limited modulation bandwidths up to 40 GHz in undoped short-cavity In(0.35)Ga(0.65)As-GaAs multiple-quantum-well lasers

We demonstrate record direct modulation bandwidth from MBE-grown In(0.35)Ga(0.65)As-GaAs multiple-quantum-well lasers with undoped active regions and with the upper and lower cladding layers grown at different growth temperatures. Short-cavity ridge waveguide lasers achieve CW direct modulation bandwidths up to 40 GHz for 6 x 130 micron(exp 2) devices at a bias current of 155 mA, which is the damping limit for this structure. We further demonstrate large-signal digital modulation up to 20 Gb/s (limited by the measurement setup) and linewidth enhancement factors of 1.4 at the lasing wavelength at threshold of ~1.1 micron for these devices.