VCSEL Characterization: LiDAR and Eye-Safety Testing

Datum: 27.09.2022, 12:00 Uhr (EST)

Justin Blanke

Ort: Detroit/MI, USA

Vertical-cavity surface-emitting lasers (VCSELs) perfectly fulfill the requirements for present and future 3D sensing applications. However, to operate VCSEL-based devices in public, the manufacturer must assure “eye safe” operation compliant with the IEC 60825-1 standard or national equivalents. As VCSELs exhibit special emission characteristics that differ from other laser sources, the safety assessment is more complex, and a practical guideline does not exist.

In this presentation, Justin Blanke, International Sales Manager at Instrument Systems, explains the differences of VCSELs as compared to “normal” collimated, Gaussian lasers, and outlines the main steps necessary for VCSEL safety assessment. Although VCSELs are intrinsically single-longitudinal mode devices, they usually show complex polarization characteristics. Most VCSEL are not designed to emit in a single polarization state. Then there is no control of the polarization angle. The light emitted by the VCSEL is typically linearly polarized along one of two orthogonal directions and abrupt polarization switching can be observed when temperature or bias current is changed. We show a method of measuring spatially resolved polarization characteristics of VCSELs. This is achieved by using a combination of polarization filtered microscope optics and a CMOS camera.

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