Characterization and optical design of VCSEL diode for application in 3D mobile Sensorsystems

Recently vertical-cavity surface-emitting lasers (VCSELs) are widely applied in smartphones and autonomous driving in which the detecting distance ranges from hundreds of millimeters to hundreds of meters. Especially for long-distance applications, well collimated VCSEL light is necessary. The precise optical design of the collimating is based on a thorough characterizations of the VCSEL beam. In our 3D sensor system, VCSEL arrays will be employed to generate a structured illumination. To simplify and standardize the characterization and optical design process of the VCSEL arrays, a similar multimode VCSEL diode is first of all applied. This paper will measure the specifications of the VCSEL diode, which include the optical output power, wavelength spectrum, beam divergence, M-squared factor, and the laser mode. To verify the results of beam divergence, two measurement methods of focal length method and two-point methods will be compared. For the M-squared factor, the Levenberg-Marquardt least-square fitting is implemented in Matlab.With these parameters, the VCSEL is designed to result in an elliptical beam profile. The design, as well as the experimental results, will be shown.