Abstract

Neodymium doped lithium niobate offers the possibility of combining laser action and non-linear effects in the same structure¹,². Low threshold, efficient, CW, proton-exchange (PE)³ waveguide lasers and amplifers at 1.085 microns have been fabricated⁴ and, recently, the integration of such a waveguide laser and an FM mode locker was demonstrated⁵. In view of the high nonlinear coefficients of lithium niobate, it would be interesting to combine parametric interactions, such as second harmonic generation (SHG), with the laser action. The "Cerenkov" doubling configuration appears to be the most interesting for this application since it provides automatic phase matching and the possibility of high efficiency, when realized with high 8n step index guides⁶. Here we report on what is, to our knowledge, the first high δn waveguide lasers in lithium niobate and the observation of SHG and sum-frequency mixing with these devices. Depending on the pumping level, the high δn devices typically lase simultaneously at several wavelengths, and while the conversion efficiencies of these first devices are rather low, essentially due to strains induced propagation losses which we shall describe, we outline the way to overcome this.

© 1992 Optical Society of America