  We present a new scheme for performing optical spectroscopy on single molecules. A glass capillary with a diameter of 600 nm filled with an organic crystal tightly guides the excitation light and provides a maximum spontaneous emission coupling factor ($\beta$) of 18% for the dye molecules doped in the organic crystal. Combination of extinction, fluorescence excitation and resonance fluorescence spectroscopy with microscopy provides high-resolution spatio-spectral access to a very large number of single molecules in a linear geometry. We discuss strategies for exploring a range of quantum optical phenomena, including coherent cooperative interactions in a mesoscopic ensemble of molecules mediated by a single mode of propagating photons. 
Coherent Interaction of Light and Single Molecules in a Dielectric   Nanoguide