Cool Epi describes a proprietary technology for fabricating lasers from thin film semiconductor materials. These thin films, called epitaxial layers or epilayers, are grown on crystalline substrates.

With CoolEpi, the thin film epilayer material is removed from the crystalline substrate and transferred to a material with much higher thermal conductivity such as copper. The technique also facilitates formation of the optical cavity resonator needed for laser operation.

The image shown here is an electron microscope image of a IV-VI semiconductor layer (a mid-infrared laser material) transferred to copper from its crystalline growth substrate. The image shows a cleaved facet, which forms one end of the optical cavity resonator. Epitaxial laser materials packaged this way will remain cool during laser operation thus removing the need for bulky external cooling systems.