In one aspect of the present invention, an apparatus includes a first light source for generating a broadband light, and a second light source for generating a monochromatic light, a beamsplitter optically coupled to the first light source for receiving the broadband light and splitting the received broadband light into a reference light and a sample light, a reference arm optically coupled to the beamsplitter for receiving the reference light and returning the received reference light into the beamsplitter, and a sample arm optically coupled to the beamsplitter and the second light source for combining the sample light and the monochromatic light, delivering the combined sample and monochromatic light to the target of interest, collecting a backscattering light and a Raman scattering light that are generated from interaction of the sample light and the monochromatic light with the target of interest, respectively, returning the backscattering light into the beamsplitter so as to generate an interference signal between the returned backscattering light and the returned reference light in the beamsplitter, and directing the Raman scattering light in an output optical path, and a single detector optically coupled to the beamsplitter for collecting the interference signal.