Gently-sloped small signal response by intra-cavity loss modulation

An intra-cavity loss modulation laser diode (ICLM-LD) was proposed and its characteristics were evaluated numerically and experimentally to realize an ultra wideband direct modulation external cavity laser. It was confirmed that the intra-cavity loss modulation can suppress the modulation sensitivity degradation over the relaxation oscillation frequency, which will be effective to widen the modulation bandwidth of external cavity assisted semiconductor laser drastically. Thanks to the suppression of the modulation sensitivity degradation, wide 3-dB bandwidth of more than 30 GHz was confirmed by the ICLM-LD.