Low chirp observed in directly modulated quantum dot lasers

We have examined the dynamic properties of high-aspect-ratio InAs-quantum-d ot (QD) lasers at room temperature. A novel characteristic of low chirp in the lasing wavelength under 1-GHz current modulation was found in the quant um dot lasers. This is more than one order of magnitude less than the typic al chirp (0.2-nm) found in a conventional quantum well laser that we used a s a reference. Low chirp was obtained not only in the ground state lasing b ut in the second level lasing of quantum dots as well.