The vertical cavity surface emitting laser (VCSEL) offers higher beam quality and reliability compared with the traditional edge emitting laser. It has significant application prospects in light imaging detection and ranging (LiDAR). The luminescence characteristics of a VCSEL with TO (transistor outline) package and a VCSEL with bare chip are examined under the narrow pulse and large current conditions. Using Pspice parameter scanning analysis, the experimental results combined with the theoretical calculation are used to compare the sizes of stray parameters and to analyze their effects on the luminescence characteristics of these two encapsulated lasers. Moreover, the formula about power conversion efficiency of a VCSEL under the pulse condition is derived and the influence of stray parameters on the power conversion efficiency of a VCSEL is analyzed.