Nanophotonics for a Green Internet

The energy required to transmit information as encoded optical and electrical data bits within and between electronic and photonic integrated circuits, within and between computer servers, within and between data centers, and... [ view full abstract ]

The energy required to transmit information as encoded optical and electrical data bits within and between electronic and photonic integrated circuits, within and between computer servers, within and between data centers, and ultimately nearly instantly across the earth from any one point to another clearly must be minimized. This energy spans between typically tens of pJpb  to well over tens of mJ for intercontinental distances. We seek to meet the exploding demand for information within the terrestrial resources available but more importantly as a common sense measure to reduce costs and to become stewards of a perpetual Green Internet. The concept of a Green Internet implies a collection of highly energy-efficient, independent, and ubiquitous information systems operating with minimal impact on the environment via natural or sustainable energy sources (1). A key enabling optical component for the Green Internet is the vertical-cavity surface-emitting laser (VCSEL).

We review our research work on energy-efficient VCSELs for application as light-sources for optical interconnects and optical fiber data communications between 850 and 1310 nm. We present VCSEL designs, design principles, and operating methods that enable data communication systems capable of 10 exp -12 bit error-free operation at bit rates exceeding 50 Gbps in the range 850-980 nm with energy efficiencies approaching 100 fJpb. Bit rates exceeding 200 Gbps by wavelength multiplexing of NRZ signals are possible for single mode devices showing an output power of 3 mW. The large linearity of the L-U-characteristics enables also higher order modulation rates like PAM4 leading to still much larger bit rates (2).

(1) For a review on Green Photonics see: G.Eisenstein and D.Bimberg, eds. „Green Photonics and Electronics”, Springer, Cham 2017

(2) G. Larisch, R.Rosales, J.A.Lott, and D.Bimberg, Proc. ESLW Bari Sept. 2018