Thermal conductivity reduction effect of thin layer on thermal resistance of vertical cavity surface emitting lasers

An accurate design of the thermal resistance of vertical cavity surface emitting lasers (VCSELs) is important for high efficiency and high output power density of a VCSEL array. Although there are reports on the thermal conductivity of a thin layer that changes from that of bulk material due to phonon scattering, its influence on VCSELs has not been clarified. In this study, we analyzed the thermal resistance of VCSELs by numerical simulation considering the thermal conductivity reduction effect of thin layer and compared it with that of experimentally fabricated devices. The device thermal resistance determined from both experimental measurements and analyzed results were 1.3–2.0 times larger than the calculated one with assuming the conventional bulk properties. The results clarified that the effect is significant and cannot be ignored when preparing an accurate device design.