Upcoming generations of coherent intra/inter data center interconnects currently lack a clear path toward a reduction of cost and power consumption, which are the driving factors for these data links. In this work, the tradeoffs associated with a transition from coherent C-band to O-band silicon photonics are addressed and evaluated. The discussion includes the fundamental components of coherent data links, namely the optical components, fiber link and transceivers. As a major component of these links, a monolithic silicon photonic BiCMOS O-band coherent receiver is evaluated for its potential performance and compared to an analogous C-band device.
We investigate numerically and experimentally sheared 2D grating couplers in a photonic BiCMOS technology with a focus on their splitting behavior. Two realization forms of a waveguide-to-grating shear angle are considered. The cross-polarization used as a figure-of-merit is shown to be strongly dependent on the grating perturbation strength and is a crucial limitation not only for the grating splitting performance, but also for its coupling efficiency.
Multiband coherent communication is being handled as a promising candidate to address the increasing demand for higher data rates and capacity. At the same time, coherent communication is expected to enter the data center domain in the near future. With coherent data links in both, data-and telecom, spanning multiple optical bands, novel approaches to coherent transceiver design and traffic engineering will become a necessity. In this work, we present a monolithically integrated silicon photonic coherent receiver for O-and C-band. The receiver features a 2 × 2 multi-mode interference coupler network as 90 • hybrid optimized for 1430 nm (E-band). The total power consumption is 460 mW at a footprint of approximately 6 mm 2 , and an opto-electrical bandwidth of 33 GHz. 64 GBd operation is demonstrated in O-and C-band, which is competitive to the state-of-the-art for silicon photonic coherent receiver in the Cband, and the highest symbol rate to date for O-band coherent communication.
We investigate fundamental properties of polarization-splitting/combining 2D grating couplers for silicon photonic coherent transceivers. Linear cross-polarization related polarization crosstalk causes signal non-orthogonality. The relevance of these effects is illustrated in a 16-QAM experiment.
Coherent techniques for short reach intra-datacenter optical interconnects are currently intensely discussed. This article reports progress on previous work that analyzed the benefits of switching from C- to O-band optics with regard to digital signal processing. Here we study the feasibility of adapting a coherent approach to an established datacenter interconnect technology (PSM4). This PSM4-like implementation brings about the benefit of much improved resilience to laser drift, thus reducing or eliminating the need for a temperature stabilized laser, which is typically assumed a requirement for coherent transceivers. The analysis rests on simulation parameters derived in part from previous experimental realizations of coherent receivers in SiGe photonic BiCMOS technology. In addition, we make use of recent results regarding the optimization of O-band 2D grating couplers with respect to efficiency and low polarization dependence over a 20nm wavelength window. We identify such couplers as enabling building blocks for coherent PSM4-like implementations.
We explore scattering effects as the physical origin of cross-polarization and higher-order modes in silicon photonic 2D grating couplers (GCs). A simplified analytical model is used to illustrate that in-plane scattering always takes place, independent of grating geometry and design coupling angle. Experimental investigations show furthermore that grating design parameters are especially related to the modal composition of both the target- and the cross-polarization. Scattering effects and the associated cross-polarization and higher-order modes are indicated as the main reason for the higher 2D GC insertion loss compared to standard 1D GCs. In addition, they can be responsible for a variable 2D GC spectrum shape, bandwidth and polarization dependent loss.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.