Contents I. Introduction
With a rapid growth of cloud services, there is a strong demand to increase a data rate capacity in data centers. To date, 100-Gb/s communication paths have been deployed in routers and networks switches. QSFP28 [1] active optical cables (AOC) have been demanded for such short reach applications. We have demonstrated CDR-integrated Sn–Ag–Cu solder reflow-capable miniature optical modules which can be applied to QSFP28 AOCs [2]–[3]. To date, 100GBASE-SR4 [4] specifies the longest distance of 100 m with an OM4 fiber at the wavelength of 850 nm. In such short reach applications, the total link cost reduction has been demanded as well as a high volume production capability. To study a low cost solution, a price of fiber cable should be taken into account. In previous works, we have demonstrated a 10-Gb/s-based optical link using a 1060-nm InGaAs/GaAs quantum well (QW) vertical cavity surface emitting laser (VCSEL) and a cost effective OM2 fiber [5]. Owing to a low chromatic dispersion, we achieved a BER of <10−12 when transmitting a 10-Gb/s optical signal in a 50-micrometer-core OM2 fiber of 300 m. Since a price of OM2 fiber is lower than that of OM3 and OM4 fibers, a low cost 28-Gb/s optical link using an OM2 fiber is expected. In this report, we describe the structure of 1060-nm VCSEL-based 4-channel miniature solderable optical modules with an integrated CDR circuitry. We transmitted a 28.05-Gb/s optical signal in different lengths of OM2 fiber on the test system experimentally. We report the results on the link test.
