Passive Si3N4 photonic integrated platform at 1μm for short-range optical interconnects

Paper in proceeding, 2019

With the increasing development of cloud services, a large number of high-speed optical interconnects are needed in large-scale datacenters. Future datacenters will require short-range links with multi-Tb/s interconnect capacity, i.e. more than an order of magnitude higher than what is available today with vertical-cavity surface-emission lasers (VCSELs) or silicon photonics. In addition, large-scale datacenters will require longer (> 1km) transmission links. Single-mode GaAs VCSELs today provide transmission speeds ∼ 100 Gb/s, close to their fundamental limit. The recent development of high-speed GaAs VCSELs at a slightly longer wavelength of opens a path forward for low-energy dissipation, high-speed, long-reach optical interconnects because the chromatic dispersion and attenuation in fibers are significantly reduced compared to shorter wavelengths [1]. In order to meet the future capacity prospects, we envision the use of multi-wavelength GaAs VCSEL arrays at 1 μm with advanced multi-fiber cables. This vision requires the use of a low-cost, low-loss passive integrated photonic platform for laser integration, multiplexing, and fiber interfacing, as sketched in Figure (a). Here, we present a silicon nitride (henceforth SiN) platform that can meet these requirements.