System and method for axially resolved light collection from a tapered waveguide

A system for light collection through a probe implanted in a tissue, said system including

• a light collecting probe comprising a waveguide formed by a single optical fiber and having a proximal end and a distal end, said proximal end being formed with a taper along which at least one optical window is positioned, wherein said single optical fiber is capable of sustaining a plurality of guided modes of light propagating in said single optical fiber, and wherein light entering at an axial section of the taper generates a respective subset of guided modes of said plurality of guided modes defined by a diameter of the single optical fiber at said axial section, said subset of guided modes propagating toward the distal end of the waveguide and generating a respective radial light intensity profile at the distal end of the waveguide;
• a demultiplexer configured to receive a plurality of said radial light intensity profiles provided by the light collecting probe and associated to a plurality of respective light input points along the taper, said demultiplexer being configured to discriminate said radial light intensity profiles based on their modal content of origin;
• and
• a detector configured to collect a far-field pattern of the discriminated radial light intensity profiles provided by the demultiplexer.