Diffusion-Bonded Crystals Address Optical Functions
Sep 2008Crystal GmbHRequest Info
• same properties as single crystals
• optical, thermal, geometrical benefits
• low scattering and loss at optical interface
Crystal GmbH has announced a new generation of composite optical crystals manufactured using diffusion-bonding technology. This method allows combinations of similar — or even dissimilar — crystalline materials without additional adhesive layers, avoiding any effect on performance by those layers, as well as improving mechanical and optical properties.
So-called bicrystals are well-known in electronics and sensor applications but have become accessible also for optical applications of crystals. This technique leads the way to components for applications in various fields of optics, laser technology and research. For example, laser slabs can be fitted with undoped end caps to reduce thermal lensing.
Another common laser application is integrating passive Q-switches to reach higher levels of laser integration and to avoid parasitic oscillations. Such parts are available in standard Nd:YAG and Cr:YAG bonded designs.
Similarly, heat sinks and supporting substrates for disc lasers can be implemented by bonding the very thin active laser disk on a heat-dissipating and mechanically supporting substrate. Crystalline optical elements beyond the size of the grown crystals now can be made, facilitating larger and more sophisticated geometrical designs.
The technique can be applied to all types of crystals, including cubic, hexagonal and tetragonal, and the bonded composite exhibits the same flexural strength and thermal shock behaviour as noncomposite samples and can be further processed in the same way as noncomposite single crystals. For optics, it is important to note that the grain boundary does not affect wavefront in laser applications and that negligible scattering centres and absorption loss have been found, leading to a high laser damage threshold.