A surgical instrument is provided that includes an elongated shaft that includes a proximal end and a distal end; a cantilever beam is disposed at the distal end of the shaft; an optical fiber extends within a channel that extends within between proximal and distal portions of the cantilever beam; a first fiber Bragg grating (FBG) is formed in a segment of the optical fiber within the proximal portion of the beam; a second FBG is formed in a segment of the optical fiber within the distal portion of the beam.