Investigation of the Fabry-Perot dip shift in VCSEL photoluminescence near-infrared reflection spectra

To obtain the deviation between the actual and designed thickness of distributed Bragg reflectors (DBRs) and resonant cavities in vertical cavity surface emitting lasers (VCSELs), the factors that affect the Fabry-Perot dip (F-P dip) shift were analyzed in detail. A basic VCSEL structure was designed and grown as a reference, and the thicknesses of the DBRs and the resonant cavity were varied. The near-infrared reflection spectra of VCSELs were measured. The results reveal that the F-P dip is influenced not only by the thickness of the resonant cavity, but also by the thickness of p-/n-DBRs. Additionally, when the thickness of either a p- or n-DBR is increased while that of the other component is decreased, the main differences in the characteristics can be observed. Finally, an effective method is proposed to obtain the layer thickness deviation by analyzing the change in the F-P dip and the central wavelength in photoluminescence near-infrared reflection spectra.