Pressure-induced shift and broadening of 1560–1630-nm carbon monoxide wavelength-calibration lines

Abstract

We have measured the line centers and the pressure-induced shifts of 14 lines in the 3ν rotational–vibrational band of carbon monoxide, 12C16O, and 18 lines in the corresponding band of 13C16O. These lines can be used as wavelength references in the optical fiber communication wavelength-division multiplexing L band (approximately 1565–1625 nm). The 12C16O spectrum has useful reference lines from 1560 to 1595 nm, and the 13C16O spectrum has lines from 1595 to 1630 nm. We observed that, except for a shift of 35 nm toward longer wavelengths for the 13C16O spectrum, the behaviors of the two isotopic species are similar. We found that the pressure shift varies with line number, from ∼+0.01 to +0.02 pm/kPa (∼0.16 to 0.31 MHz/Torr). In addition, we measured the pressure broadening of these lines; we found that it also varies with line number and is typically 0.3–0.4 pm/kPa (approximately 5–7 MHz/Torr).