Threshold control in VCSELs by proton implanted depth

The proton implantation is one of key procedures to confine the current diffusion in vertical cavity surface emitting lasers（VCSELs）,in which the proton implanted depth and profile are main parameters.Threshold characteristics of VCSELs with various proton implanted depths are studied after optical,electrical and thermal fields have been simulated self-consistently in three dimensions.It is found that for VCSELs with confinement radius of 2 mm,increasing proton implanted depth can reduce the injected current threshold power and enhance the laser temperature in active region.Numerical results also indicate that there are optimal values for current aperture in proton implanted VCSELs.The minimum injected current threshold can be achieved in VCSELs with proton implantation near the active region and confinement radius of 1.5 mm,while the VCSELs with proton implantation in the middle of p-type distributed Bragg reflectors（DBRs） and confinement radius of 2.5 mm can realize the minimum temperature.