Apart from electro-optics applications, RTP crystals (Rubidium Titanyl Phosphate) also offer interesting features for frequency conversion including: High damage threshold No grey track Small walk-off angle when used for generation of wavelengths in the yellow rangeHas very similar features to KTP but adds the benefit of a good optical transmission between 3µm and 3.5µm: Transparent between 0.5µm and 3.5µm High non-linear optical efficiency Large temperature acceptance Lower birefringence than KTP resulting in a smaller walk-off It is often used as an OPO / OPA gain medium for emission in the 3µm range as well as an OPO crystal for eye-safe emission at high average power.