Compact Tunable Mid-infrared Source Based on PPLT Whispering Gallery Mode Resonators*

We demonstrate a tunable optical parametric oscillator in a periodically poled congruently grown lithium tantalite (PPCLT) whispering-gallery-mode resonator. The resonator is mechanically polished to millimeter size, and the quality factor is approximately 10^7 at 1064nm. Our experiments show that this kind of resonators are capable of reaching very low threshold with 57.6% slope efficiency and having wide tuning range from 1.7 to 2.85μm. Combining with its narrow resonant linewidth, it is potentially used as compact, widely tunable and narrow linewidth infrared to mid-infrared laser source.