Contents Introduction
Directly modulated lasers (DMLs) are one of the most important devices in short-reach optical interconnects and networks due to their low power consumption and compact size1–3. Modulation frequencies of >50 GHz have previously been achieved with gain-modulated DMLs3 by increasing the laser relaxation oscillation frequency . Nevertheless, the traditional gain-modulated DMLs have some intrinsic limitations such as high chirp, small wavelength tunablity, and limited modulation formats. The speed limitations imposed by the could be overcome by modulating the reflectivity of the Bragg mirror in distributed Bragg reflector laser4, the intra-cavity loss5–7 and the coupling in a ring cavity laser8, Nevertheless, only a few Gb/s modulations were experimentally demonstrated for the above non-gain modulated lasers7,8.
