Abstract

The expected, higher differential gain of long- wavelength quantum-well lasers has led to interest in using quantum-well lasers rather than bulk lasers to achieve higher modulation band- widths. Much less attention has been paid to the limit that the damping of the relaxation oscillations imposes on the maximum achievable modulation bandwidth in quantum-well lasers. In this work we show that 1.5-μm quantumwell lasers with few wells can be very highly damped; for example, a three-well laser is estimated to have a bandwidth limit of only 9 GHz. Only in the case of lasers with many wells does the damping approach the typical bulk values. Furthermore, the damping is found to be related to the number of quantum wells and/or optical confinement factor, and not to gain saturation.

© 1991 Optical Society of America