Spectroscopic studies of atomic and molecular species relevant to the optical fibre transmission bands

The work presented in this thesis, although all relevant to wavelength standards in the optical fibre transmission windows at 1.3μm and 1.55μm, can be split into three main parts. Firstly, the work carried out at the University of Strathclyde concerning accurate line position measurements of some molecules having absorption bands at 1.5μm (15NH3, C2H2 and 13C12CH2) and 1.3μm (13C2D-2 and 12C2D2) with a Fourier transform spectrometer (FTS). The FTS measurements were undertaken primarily to provide a comprehensive list of fairly strong lines relevant to the optical fibre regions as potential wavelength references for the National Physical Laboratory (NPL). The 13C12CH2 overtone and combination bands were assigned and fitted. Secondly, the development of two diode laser spectrometers was carried out at the University of Strathclyde to perform an optical double resonance experiment in which an excited state transition in Rubidium at 1.53μm was observed. Further development of this may lead to a useful wavelength standard in the 1.5μm window. Lastly, a series of experiments carried out at NPL examining the potential of an optogalvanic based frequency stabilisation scheme for the 1.52μm He-Ne laser with regard to developing a primary wavelength standard based on the He-Ne. Optogalvanic signals were recovered for a number of configurations and further work is required particularly with Ne filled hollow cathode discharge tubes to establish the usefulness of such a scheme. (author)