Performance of Ar⁺-milled Ti:sapphire rib waveguides as single transverse mode broadband fluorescent sources

Rib waveguides have been fabricated in pulsed-laser-deposited Ti:sapphire layers using photolithographic patterning and subsequent Ar+-beam milling. Fluorescence output powers up to 300µW have been observed from the ribs following excitation by a 3W multiline argon laser. Mode intensity profiles show high optical confinement and the measured beam propagation factors Mx2 and My2 of 1.12 and 1.16 respectively, indicate single transverse mode fluorescence emission. Loss measurements using the self-pumped phase conjugation technique have yielded comparable values (1.7dB/cm) for the ribs and the unstructured planar waveguide counterparts. The combination of optimum modal properties and strong optical confinement, together with sufficient levels of fluorescence output, make the single-moded Ti:sapphire rib waveguides a very interesting candidate as a fluorescence source for optical coherence tomography applications