Highly integrated optical modules for >= 400-G coherent optical links

Small coherent optical transceivers have been demanded to provide a high data rate density in next-generation metro-area networks and data-center interconnects. Therefore, the mechanical sizes of optical modules and sub-assemblies have been shrinking, and accordingly, highly integrated optical modules have been demanded. We present two types of highly integrated optical modules for >= 400-Gb/s coherent optical links. Our wavelength-tunable laser module consists of an ultra-compact DBR/Ring laser chip and a PLC-based wavelength locker. The laser module covers the wavelength range of full C-band with a narrow linewidth of <100 kHz and a fiber output power of 17 dBm. Furthermore, we demonstrate a tiny transmitter-receiver optical sub-assembly that integrates all required optical components into a single gold-box of 26 x 14 x 4 mm in compliant with the Optical Internetworking Forum (OIF) specifications. The electrical-optical and optical-electrical bandwidths measure >40 GHz, which is wide enough to realize >= 400-Gb/s per lambda operations.