Thermal management optimization in high-power 3D sensing VCSELs

A. Filipchuk; K. Nechay; R. Ulkuniemi; S. Talmila; P. Uusimaa

doi:10.1117/12.2608551

4 March 2022 Thermal management optimization in high-power 3D sensing VCSELs

A. Filipchuk, K. Nechay, R. Ulkuniemi, S. Talmila, P. Uusimaa

Proceedings Volume 11982, Components and Packaging for Laser Systems VIII; 119820E (2022) https://doi.org/10.1117/12.2608551
Event: SPIE LASE, 2022, San Francisco, California, United States

Abstract

Vertical-cavity surface-emitting lasers (VCSELs) have recently paved their way into the 3D sensing market, specifically in mobile device applications. Vertical emission of VCSELs enables arranging single emitters into high-power 2D arrays. Thus, VCSEL arrays require efficient heat management which can be implemented by the means of packaging, both to improve thermal conductivity and to keep VCSEL chips intact. This becomes particularly important when considering also very high-density laser arrays and 2D matrices for quantum computing targeting a larger number of parallel outputs. Despite VCSELs decreased temperature sensitivity, their internal efficiency strongly depends on the internal temperature rise, which is defined by the dissipated power and thermal impedance of the laser assembly. Thermal impedance effect is more notable in the proximity to the gain medium, resulting into a drastic temperature gradient due to relatively thick substrate and its poor thermal conductivity. This prevents efficient heat dissipation in the gain media and creates a need for additional heat sinking. In this work, the improved heat sinking is implemented by packaging VCSEL arrays onto AIN sub mounts and subsequently encapsulating them into a thermally conductive and optically transparent epoxy. Thus, the closest proximity of the gain media to the heat sink is established, leading to an enhanced heat flow. Quantitative evaluation of the heat flow is performed by determining thermal resistance, defined as a ratio of the shift rates in the emission spectrum produced by varying pumping current and the heat sink temperature. The evaluation of thermal resistance of the devices with and without epoxy, not reported earlier, is performed to quantitively demonstrate the obtained improvements in the heat flow, efficiency, and output power.

Conference Presentation

Citation Download Citation

A. Filipchuk, K. Nechay, R. Ulkuniemi, S. Talmila, and P. Uusimaa "Thermal management optimization in high-power 3D sensing VCSELs", Proc. SPIE 11982, Components and Packaging for Laser Systems VIII, 119820E (4 March 2022); https://doi.org/10.1117/12.2608551

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