Effects of Thermal-Via Structures on Thin-Film VCSELs for Fully Embedded Board-LevelOptical Interconnection System

The thermal characteristics of a thin-film vertical-cavity surface-emitting laser (VCSEL) are studied both theoretically and experimentally. The thermal resistances of the VCSEL with variable thickness, ranging from 10 to 200 mum, have been determined by measuring the output wavelength shift as a function of the dissipated power. The thermal simulation results agree reasonably well with the experimentally measured data. From the thermal management viewpoint, a thinned VCSEL has an exclusive advantage due to the reduction of the thermal resistance. The thermal resistance of a 10-mum-thick VCSEL is 40% lower than that of a 200-mum-thick VCSEL. A theoretical analysis of the thermal-via effects is performed to determine the optimized thickness range of thin-film VCSEL for the fully embedded structure. The thermal resistance of the fully embedded thin-film VCSEL with closed and open thermal-via structures is also evaluated, and the suitable VCSEL thickness is reported