Events Calendar

ECE Seminar: Pierluigi Debernardi

Title: Modeling VCSEL Modes: From the Beginnings to New Geometries and Future Applications

Abstract: In my talk, I will introduce our VCSELs Electromagnetic Simulation Software Suite (VELMS) and discuss its evolution over the past 25 years since its initial release. At the time, Vertical Cavity Surface Emitting Lasers (VCSELs) had limited market applications. Since then, VCSELs have steadily expanded their presence, gaining significant market share. VELMS has evolved in parallel, incorporating the necessary features to meet the demands of emerging sensing and datacom systems. For instance, position-sensing VCSELs, based on our surface grating proposal and demonstration, are now widely used in laser mice and smartphones. Depending on the application, these devices can range from dozens to several hundred sensing VCSELs.

In the sensing domain, where single-mode operation is critical, new applications are rapidly emerging, particularly in autonomous driving and vehicle safety systems. LIDAR technology, which requires high power, has driven the development of multi-(tunnel) junction VCSELs, coupled with traditional oxide confinement techniques. This can be further enhanced by specialized VCSEL transverse array geometries to achieve single-mode operation in a high-order mode through reflection patterning. In this paper, we will present examples of potential geometries.

Another major market for VCSELs is datacom, especially in the context of data centers. The demand in this sector is skyrocketing, driven by the growing needs of AI (artificial intelligence) applications, which require the construction of massive new data centers. Of course, faster speeds are also essential. I will share our modeling of dumbbell-shaped oxide-aperture VCSELs, which show promise in achieving 200G datacom via a single VCSEL using PAM-4 modulation.

Bio: Pierluigi Debernardi received his degree in Electronics Engineering in 1987 from Politecnico di Torino, Torino, Italy. Since 1989, he has been with the Istituto Elettronica e Ingegneria Informazione Telecomunicazioni, part of the Italian National Council of Research, based at the Politecnico di Torino. His interests are mainly in the field of the modelling of semiconductor materials and devices for optoelectronic applications. Over the last 25 years, he has focused on modelling and designing VCSELs of various transverse geometries (dumbbell, arrays, donut), aiming for specific modal properties for specialised applications: high power, high speed, and circular/elliptical polarisation for atomic devices.