Very-high-bit-rate integrated photonic devices for next-generation Ethernet

Recent advances in integrated photonic devices for next-generation Ethernet are described. In particular, 1.3-μm-range uncooled photonic devices (namely, electroabsorption modulator integrated lasers, directly modulated lasers, and lens integrated devices) are focused on. A key technology for uncooled operation is an InGaAlAs multiple quantum well (MQW), which produces a strong electron confinement. The electroabsorption modulator integrated lasers, which incorporated an InGaAlAs-MQW absorption layer, exhibit uncooled 25.8-Gbit/s and 43-Gbit/s single-mode fiber 10-km transmissions. The 1.3-μm directly modulated laser, which consists of an InGaAlAs MQW distributed feedback (DFB) active stripe, exhibits uncooled direct modulation at 25 Gbit/s. To improve the optical coupling of the directly modulated laser, we developed a lens-integrated surface-emitting laser, which incorporates an InGaAlAs DFB active stripe. This lens-integrated laser exhibits 25-Gbit/s direct modulation up to 100°C. Furthermore, the lens-integrated photodiode exhibited high speed (35 GHz), high responsivity (0.8 A/W), and large alignment tolerance (26 μm) for direct coupling to a single-mode fiber. These photonic devices have demonstrated their potential for implementation in cost-effective 100-Gbit/s and 40-Gbit/s Ethernet.