SERS probe comprising a dual-core optical fiber and a spacer onto which SERS-active nanoparticles are attached

A spectroscopy probe apparatus comprising an excitation path configured to transmit excitation light for exciting a response; a collection path different from the excitation path and configured to transmit signal light comprising a response signal, wherein at least one of the excitation path or collection path comprises or is formed in at least one optical fibre; and a light guide having a proximal end coupled to the excitation path and to the collection path, wherein the guide is configured to pass the excitation light from the excitation path to a target region to generate the response signal, and to pass the signal light comprising the response signal from the target region to the collection path.