Influence of Resonator Length on Performance of Nitride TJ VCSEL

This paper presents computer simulations of nitride-based tunnel-junction (TJ) vertical-cavity surface emitting lasers (VCSELs). The analyzed structures are non-polar continuous wave VCSELs with dielectric distributed Bragg reflectors (DBRs) emitting at around 405 nm. Both electric contacts are in the form of rings that surround the DBRs. The bottom electric contact also acts as a thermal contact between the laser and the heat sink, because the dielectric DBR is a thermal insulator. The results of our study show that the thickness of the laser's resonator and its absorption coefficient each have a very strong impact on both the threshold current and emitted power. A thick resonator reduces the thermal resistance of the device, but increases the optical absorption. The optimal resonator thickness depends on the absorption coefficient of the resonator material, different possible values for which are investigated here. Moreover, VCSELs with TJs has been compared with similar devices, with semi-transparent ITO contacts and without a TJ.