HIGH POWER SEMICONDUCTOR LASER DIODES

摘要

A high power laser source comprises a bar of laser diodes, a submount onto which said laser bar is affixed, and a cooler onto which said submount is affixed. The laser bar has a first coefficient of thermal expansion (CTEbar), the submount has a second coefficient of thermal expansion (CTEsub), and the cooler has a third coefficient of thermal expansion (CTEcool), the third coefficient (CTEcool) being higher than both said first coefficient (CTEbar) and said second coefficient (CTEsub). According to the invention, the second coefficient (CTEsub) is selected lower than both the first coefficient (CTEbar) and the third coefficient (CTEcool), contrary to the usual approach with the CTEsub matching the CTEbar. A preferred range is CTEsub= k * CTEbar, with 0.4 < k < 0.9. The submount may consist of or comprise two or more layers of different materials having different CTEs, e.g. a Cu layer of about 10-20µm thickness and a Mo layer of about 200-300µm thickness, resulting in a CTEsub which varies across the submount's thickness. Alternatively, the submount may consist of a single, more or less homogeneous material with a CTEsub varying across the submount's thickness. A method for making such a high power laser source includes selecting a submount whose CTEsub lies between the CTEcool of the cooler and the CTEbar of the bar of laser diodes and hard soldering the bar and the cooler to the submount.