Dresden 2014 – scientific programme

Parts | Days | Selection | Search | Updates | Downloads | Help

HL: Fachverband Halbleiterphysik

HL 14: Invited Talk James Lott

HL 14.1: Invited Talk

Monday, March 31, 2014, 11:45–12:15, POT 151

Vertical-cavity surface-emitting lasers (VCSELs) for optical interconnects — •James A. Lott — Zentrum für Nanophotonik, Institut für Festkörperphysik, Technische Universität Berlin, Sekr. EW 5-2, Hardenbergstraße 36, D-10623 Berlin, Germany

Ubiquitous vertical-cavity surface-emitting lasers (VCSELs) are at present the smallest practical commercially-deployed class of laser. Reliable, mass-produced VCSELs capable of operating at 10-14 Gbit/s with an energy efficiency of about 400-800 fJ/bit are the indispensable workhorse of modern short-reach (SR < 300 m) optical interconnects (OIs) in data centers and peta-FLOPS-class supercomputers. In this work we disclose our methods and wavelength-independent "Principles" of VCSEL design and operation, based on our many years of extensive experimental and numerical materials and device studies, that simultaneously lead to the optimization of three critical VCSEL attributes: 1) energy efficiency; 2) temperature stability; and 3) directly current-modulated bit rate. Our amazing record-performing 850 nm VCSELs operate error free across multimode fiber at 25-40 Gbit/s with energy efficiencies in the range 50-110 fJ/bit, including back-to-back at 40 Gbit/sec at 85°C. We next disclose our most recent work on ultrafast 980 nm VCSELs targeted for very-short-reach (VSR < 1 m) and ultra-short-reach (USR < 1 mm) OIs for on-chip, inter-chip, free-space, and exa-FLOPS-class supercomputers of circa 2020-2030, where billions of VCSEL-based OIs are envisioned in each supercomputer. We present record 50 Gbit/s at 25°C and ~179 fJ/bit operation at 38 Gbit/s at 85°C. We conclude with our perspectives on a practical OI roadmap through circa 2050.

* In collaboration with (in alphabetical order): D. Bimberg, G. Larisch, H. Li, A. Liu, P. Moser, and P. Wolf, all with the Technische Universität Berlin.