Directly modulated deformed-square-FP coupled-cavity laser with intracavity-mode photon-photon resonance.

We propose and demonstrate a high-speed directly modulated laser based on a hybrid deformed-square-FP coupled cavity (DFC), aiming for a compact-size low-cost light source in next-generation optical communication systems. The deformed square microcavity is directly connected to the FP cavity and utilized as a wavelength-sensitive reflector with a comb-like and narrow-peak reflection spectrum for selecting the lasing mode, which can greatly improve the single-mode yield of the laser and the quality (Q) factor of the coupled mode. By optimizing the device design and operating condition, the modulation bandwidth of the DFC laser can be enhanced due to the intracavity-mode photon-photon resonance effect. Our experimental results show an enhancement of 3-dB modulation bandwidth from 19.3 GHz to 30 GHz and a clear eye diagram at a modulation rate of 25 Gbps.