An optical fiber sensor (100; 400; 500; 600; 1100; 2000) comprising: a lead-in optical fiber (102; 502) having an end surface at a forward end; and a first optical element (107; 407A; 507; 607; 707; 1100; 1600) having a body with an outer diameter Do, a rearward-facing first end coupled to the forward end of the lead-in optical fiber, a forward-facing second end opposite the first end, a solid support base on the forward-facing second end, and a pedestal (120; 420) including a retracted surface that is reflective, the retracted surface projecting rearwards and being retracted inwardly relative to the rearward-facing first end of the optical element, wherein the retracted surface and a second surface define an optical cavity (108; 408; 2008), and the second surface is (a) the end surface of the lead-in optical fiber or (b) a reflective surface of an intermediary component (312; 407A; 507A) between the lead-in optical fiber and the first optical element, the first optical element further having a gutter (117; 417; 617; 2017) surrounding the pedestal and penetrating forward into the solid support base, and a tail portion that extends beyond a forward end of the gutter (117; 417; 617) by a distance greater than Do/2; wherein the gutter has a gutter depth defining an active region of length L, the first optical element exhibiting L/Do ≥ 0.5, and wherein the optical fiber sensor is sensitive to elongation of the active region. a lead-in optical fiber (102; 502) having an end surface at a forward end; and a first optical element (107; 407A; 507; 607; 707; 1100; 1600) having a body with an outer diameter Do, a rearward-facing first end coupled to the forward end of the lead-in optical fiber, a forward-facing second end opposite the first end, a solid support base on the forward-facing second end, and a pedestal (120; 420) including a retracted surface that is reflective, the retracted surface projecting rearwards and being retracted inwardly relative to the rearward-facing first end of the optical element, wherein the retracted surface and a second surface define an optical cavity (108; 408; 2008), and the second surface is (a) the end surface of the lead-in optical fiber or (b) a reflective surface of an intermediary component (312; 407A; 507A) between the lead-in optical fiber and the first optical element, the first optical element further having a gutter (117; 417; 617; 2017) surrounding the pedestal and penetrating forward into the solid support base, and a tail portion that extends beyond a forward end of the gutter (117; 417; 617) by a distance greater than Do/2; a body with an outer diameter Do, a rearward-facing first end coupled to the forward end of the lead-in optical fiber, a forward-facing second end opposite the first end, a solid support base on the forward-facing second end, and a pedestal (120; 420) including a retracted surface that is reflective, the retracted surface projecting rearwards and being retracted inwardly relative to the rearward-facing first end of the optical element, wherein the retracted surface and a second surface define an optical cavity (108; 408; 2008), and the second surface is (a) the end surface of the lead-in optical fiber or (b) a reflective surface of an intermediary component (312; 407A; 507A) between the lead-in optical fiber and the first optical element, (a) the end surface of the lead-in optical fiber or (b) a reflective surface of an intermediary component (312; 407A; 507A) between the lead-in optical fiber and the first optical element, a gutter (117; 417; 617; 2017) surrounding the pedestal and penetrating forward into the solid support base, and a tail portion that extends beyond a forward end of the gutter (117; 417; 617) by a distance greater than Do/2;