Directly modulated lasers are cost-effective optical transmitters with low power consumption. We present two of our developed lasers. The first is membrane lasers on SiO2/Si for silicon photonics. The power consumption is 100-fJ-class per bit due to the large optical confinement. The bandwidth reaches 30 GHz but is limited by the thermal problem coming with low-thermal-conductivity SiO2. The latter, membrane lasers on SiC, are for beyond 400GbE. The high-thermal-conductivity and low-refractive-index SiC resolves the thermal problem while maintaining the optical confinement, resulting in 60-GHz bandwidth. This indicates that SiC is adaptable for not only high-power electronics but also laser technology.
Suguru Yamaoka has been a researcher at NTT Device Technology Labs since 2017. He is involved in directly modulated membrane lasers for high-speed and low-power-consumption operation. In particular, he introduced the new substrate, SiC, into membrane lasers in place of the conventional Si substrate. By combining optical feedback technology that further enhances bandwidth, he has developed 100-GHz-class directly modulated lasers for beyond 400 GbE. He received his Ph.D. degree in applied physics from Osaka City University, Osaka, Japan, in 2021, where he studied the optical properties of self-trapped excitons in β-Ga2O3.