High-frequency-stability laser at 15 μm using Doppler-free molecular lines

An extended-cavity 1.5-microm semiconductor laser was frequency stabilized to saturated-absorption lines of acetylene. Its long-term frequency stability is of the order of 10(-12), with a reproducibility of +/-10 kHz. Using the lines of C(2)H(2) or HCN, we could obtain such a high stability with the same laser at many wavelengths covering the 1.51-1.56-microm band.