We have continuously tuned between 7 and 15 &mgr;m by mixing the output of a LiNbO3parametric oscillator in the chalcopyrite AgGaSe2. We have doubled a CO2laser with 2.7% efficiency which agrees very well with the expected efficiency and verifies the high optical quality of the 1.53‐cm‐long AgGaSe2crystal. The measured transparency range, indices of refraction, and nonlinear coefficient ofd36= (3.7 ± 0.6) × 10−11m/V show that AgGaSe2is a useful infrared nonlinear material phase matchable over the entire 3–18‐&mgr;m infrared region.