Manufacturing and characterization of frequency tripling mirrors

In the course of continuous innovations in photonic integration optical components with ever decreasing size and increasing performance are gaining of importance in a wide range of applications. In addition, a trend towards shorter wavelengths in modern photonic systems can be observed, and frequency conversion units are commonly employed add-on modules for most laser types. Especially considering conversion to the third harmonic (TH) wavelength, present concepts are based on two second-order nonlinear processes involving two conversion crystals. Even though corresponding modules are commercially available, there is a need for simpler solutions that can be further scaled down and handled in automated assembly systems. One possibility is direct third-harmonic generation (THG) in a third-order process [1] . However compared to second-order processes, phase matching imposes a certain challenge here, because the refractive index differences between the fundamental and third harmonics are significantly larger for typical conversion materials.