A self-operating optofluidic spectrometer

Abstract

Miniaturization of Fourier transform spectrometers must necessarily deal with the problem of the mechanical scan of an interferometer, which is the core element of this technology. Several small-scale FT spectrometers with no moving parts have been demonstrated over the last years, although they all rely on advanced integrated photonics technology. We have shown previously that spectrum of an unknown radiation can be accurately measured with the simplest of the optofluidic systems: a droplet evaporating on a partially reflective substrate. This principle allows to devise a miniaturized FT spectrometer with a spontaneous evaporation-driven scan. Here, we show that such optofluidic spectrometer can be employed for the readout of a plasmonic nanostructured optical fiber sensor, allowing to devise a plasmonic sensing setup where either radiation source, sensor and readout spectrometer are all integrated in an optical fiber. The system performance is analogous to that of a macroscopic plasmonic setup, but it can be obtained with a dramatically reduced cost and dimensions.