We report on saturated-absorption spectroscopy of (H2O)-O-18 at 1.39 mu m b
y means of a low-power distributed feedback diode laser. In the transit-tim
e regime, we observed a 2.5 MHz wide line. This is the first narrow resonan
ce in the spectral window around 1.4 mu m. Possible applications in metrolo
gy are discussed. In addition, we propose some experimental schemes to meas
ure the absolute frequency of (H2O)-O-18 lines in this spectral region.