100G VCSELs for bidirectional multi-mode links

Abstract

The entry of 100G 850 nm VCSELs enables the replacement of copper by multimode fiber in switch-toserver links, and facilitates the upgrade of switch-to-switch links in enterprise networks and data centers. This paper will present the key features and characteristics of multimode VCSELs that enable direct modulation at 100 Gb/s suitable for multimode Ethernet and Fibre Channel standards. Beyond 100G, a bidirectional link using VCSELs of two wavelengths is one potential solution to double the aggregate data rate on duplex fiber links. Elements of both 850 and 910 nm VCSELs that would enable the next generation data links are described.

Development and characterization of 100Gb/s 940nm VCSELs for multimode optical links

“…The link model developed by Broadcom suggests that a small-signal modulation bandwidth over 25GHz and RIN lower than -145dB/Hz over temperatures are required for suitable margin on a 100Gb/s link with PAM-4 modulation [1]. Corresponding optical modulation amplitude (OMA) into the fiber needs to exceed 1mW for the equalization to compensate the link penalties arising from relative intensity noise (RIN), mode partition noise (MPN) and intersymbol interference (ISI) [4]. Figure 1 shows LIV curves of a typical VCSEL measured at 5, 30 and 75°C.…”

“…The Ethernet standard IEEE 802.3 VR4 has directed a wide wavelength range from 844nm to 948nm for optical fiber links, allowing wavelength windows other than 850nm to be implemented. For example, the 910nm 100Gb/s VCSEL has been applied in a bidirectional configuration together with the 850nm VCSELs to double the aggregate data rate to 200Gb/s [4]. The 940nm VCSELs together with the 850nm, 880nm and 910nm devices can be applied in a shortwave wavelength division multiplexing (SWDM) system, which is a low-cost solution to boost the data rates to 400Gb/s per lane with high performance facilitated by a wideband OM5 fiber.…”