For High-Power Lasers, Thin Is Cool

Adolf Giesen, University Stuttgart, Institute Strahlwerkzeuge

High-power diode-pumped solid-state lasers promise to provide small, versatile, rugged light sources for applications from the factory to the cleanroom. Commercial devices that take advantage of the latest generation of high-power diodes can produce tens of watts for industrial and scientific applications.
Producing higher powers in a compact device is problematic. As their power increases, so does the temperature inside the laser cavity. This produces an effect known as thermal lensing, which degrades the quality of the laser beam. Ultrahigh-power (kilowatts) solid-state lasers minimize the problem by combining beams from several cavities a solution that creates an immense device.
A more effective and compact solution, the thin-disc laser (Figure 1), turns traditional laser cavity design on its head, creating an efficient cooling and optical system that produces high output powers with the additional benefit of wavelength flexibility. Commercial applications for the technology include laser welding, cutting, drilling, marking and micromachining, where the device's excellent efficiency can result in tremendous utility savings and its size and beam quality rival other laser competition. Scientific applications include "optical tweezers," Raman spectroscopy and other applications that require efficient, high-power light sources in the infrared, visible and ultraviolet (the latter reached through harmonic conversion).