Abstract

The generation of coherent infrared radiation in nonlinear optical (NLO) crystals represents an effective method due to high efficiency and wide tunability. Among all the NLO crystals that are transparent in the mid-IR and far-IR, GaSe is very attractive since it can satisfy phase matching (PM) conditions in a large wavelength range.^1,2 There has been impressive progress of using GaSe crystals towards the efficient generation of mid- IR in the past. Among all the previous results the widest tuning range is 3–20 μm, which is generated by using intense femtosecond laser pulses.’ Here, we report our first result of achieving the coherent mid-IR and far-IR radiations with ex- tremely-wide tunability and narrow linewidth in a GaSe crystal. As shown below, we have extended the output wavelengths to the far-IR.

© 2002 Optical Society of America