Thermal Properties of High Power Laser Bars Investigated by Spatially Resolved Thermoreflectance Spectroscopy

TL;DR

This paper uses spatially resolved thermoreflectance spectroscopy to analyze the thermal properties of high-power laser bars, providing detailed temperature mapping that enhances understanding of thermal processes and device reliability.

Contribution

It introduces a high-resolution thermoreflectance technique for thermal analysis of laser bars, offering new insights into facet thermal behavior and reliability improvements.

Findings

Temperature mapping over 300 μm x 300 μm area

Enhanced understanding of facet thermal processes

Potential for increased device reliability

Abstract

In this work we present results of the analysis of thermal properties of high-power laser bars obtained by spatially resolved thermoreflectance (TR) spectroscopy. Thermoreflectance is a modulation technique relying on periodic facet temperature modulation induced by pulsed current supply of the laser. The periodic temperature change of the laser induces variation of the refractive index and consequently modulates probe beam reflectivity. The technique has a spatial resolution of about ~1 $\mu$m and can be used for temperature mapping over 300 $\mu$m x 300 $\mu$m area. Information obtained in these experiments provide an insight into thermal processes occurring at devices' facets and consequently lead to increased reliability and substantially longer lifetimes of such structures.