10-channel optical transmitter module operating over 10 Gb/s based on VCSEL and hybrid integrated silicon optical bench

Demand for higher and higher bandwidth and connection density, along with stringent cost constraints, is continuously increasing both in the interconnection field and in the optical communication networks. Parallel optical interconnection devices appear particularly suitable for these applications, featuring also low loss and cross-talk, small size and low power consumption. In this paper we report on the development of a 10-channel parallel optical transmitter module for subsystems interconnection in switching nodes of telecommunication networks, or in the connection between computers. The compact metal-ceramic module includes a 10-channel flip-chip VCSEL array emitting at 850 nm, optically coupled to a standard 50/125 multi-mode fiber ribbon pigtail through a Silicon Optical Bench (SiOB). This SiOB, designed at CSELT and microfabricated at I.M.T. of Neuchatel University, enables an effective multiple optical coupling by a passive technique, crucial to attain a low cost, along with the use of VCSEL (Vertical Cavity Surface Emitting Laser). A CMOS IC laser driver, completely designed at CSELT, with balanced PECL (Pseudo Emitter Coupled Logic) interface, is hybrid integrated in the module. During thorough lab tests the module operated at over 1 Gb/s/ch with a BER (Bit Error Rate) of 1.10(-13) and an interchannel cross-talk power penalty lower than 1 dB. The low power consumption (85 mW/ch) allowed an effective passive thermal management only through the package. In the paper the physical structure, the fabrication techniques and the characterization results of the device are discussed.