Electrically-pumped compact hybrid silicon microring lasers for optical interconnects

Di Liang,John E Bowers,Hsu-Hao Chang,Alexander W Fang,Ying-Hao Kuo,Marco Fiorentino,Daoxin Dai,Tadashi Okumura,Raymond G Beausoleil,Daryl T Spencer

doi:10.1364/oe.17.020355

Abstract

We demonstrate an electrically-pumped hybrid silicon microring laser fabricated by a self-aligned process. The compact structure (D = 50 microm) and small electrical and optical losses result in lasing threshold as low as 5.4 mA and up to 65 degrees C operation temperature in continuous-wave (cw) mode. The spectrum is single mode with large extinction ratio and small linewidth observed. Application as on-chip optical interconnects is discussed from a system perspective.

Highlights

Diode lasers with ring or disk resonator geometries are one of the most attractive on-chip light sources for photonic integrated circuits (PICs) since their inherent traveling wave operation nature requires no gratings or Fabry-Perot (FP) facets for optical feedback [1]
We demonstrate an electrically-pumped hybrid silicon microring laser fabricated by a self-aligned process
Future devices with smaller diameters and improved processing are expected to result in lower thresholds, higher power and higher temperature operation for optical interconnects

Summary

Introduction

Diode lasers with ring or disk resonator geometries are one of the most attractive on-chip light sources for photonic integrated circuits (PICs) since their inherent traveling wave operation nature requires no gratings or Fabry-Perot (FP) facets for optical feedback [1]. The first on-chip light source fabricated on HSP employs a racetrack ring resonator geometry [9] but retains the same cross-sectional structure as that of straight Fabry-Perot (FP) ones [8] It consisted of a 1-2 μm wide SOI waveguide covered by a wider III-V mesa, which leads to a hybrid mode that spans both III-V and Si. The poor lateral optical confinement for the hybrid optical mode requires the bend radius ≥100 μm such that resulting excess bending loss is smaller than available gain. Further reduction in threshold and device footprint was demonstrated by a 7.5 μm-diameter disk laser integrated on SOI substrate with polymer-based wafer bonding technique [11], showing the potential to realize on-chip Si light sources with low power consumption and high-speed direct modulation using a compact micro-ring/disk structure. In this paper we demonstrate the electrically-driven version of this compact microring laser and discuss their potential application for optical interconnects from a system perspective

Device design and fabrication

Experimental results

Applications

Conclusion