Dramatic enhancing of fluorescent light collection efficiency from a very thin layer of polymer on a planar glass substrate

There is an increasing demand for the efficient collection of fluorescent light emitted from a very thin layer of polymer material such as the specifically synthesized polymer material used in TNT explosives detection. However, the enormous transparency of this thin film poses a severe challenge for any light detection system based on a traditional approach. For a simple two-fiber architecture with one fiber for excitation light delivery and another for emission collection, we report that by launching the excitation light to one corner edge of a planar glass substrate covered with a thin layer of polymer film, we are able to simultaneously dramatically enhance the collectable fluorescent signal level and reduce the level of stray excitation light. The proposed sensing architecture opens up an efficient way of light coupling and collecting for fluorescent-related chemical and biological sample assay