A sensor (100; 200; 300; 400; 500; 600) for sensing biometric information, comprising: a light emitting unit (110; 210; 310; 410; 510; 610-1, 610-2) configured to emit a first plurality of light rays; a light receiving unit (120; 220; 320; 420; 520; 620-1, 620-2) configured to receive a second plurality of light rays, wherein the second plurality of light rays includes a portion of the first plurality of light rays reflected by a body of a user; wherein the light emitting unit (110; 210; 310; 410; 510; 610-1, 610-2) is arranged in the same plane as the light receiving unit (120; 220; 320; 420; 520; 620-1, 620-2); and an optical layer (130; 230; 330; 430; 530; 630; 1130) placed over the light emitting unit and the light receiving unit having a first surface (11; 21; 31; 51; 61) facing the light emitting unit and the light receiving unit and a second surface (12; 22; 32; 52; 62) opposite the first surface, wherein the optical layer includes: a first protrusion structure (233; 333; 533; 633) formed on the first surface and including a plurality of asymmetrical protrusion units, each of the asymmetrical protrusion units having an asymmetrical structure about a horizontal or about a vertical axis; wherein; the plurality of asymmetrical protrusion units are inclined away from the light receiving unit such that light rays incident on the optical layer are refracted away from the light receiving unit; and a second protrusion structure (131; 531; 631) formed on the second surface, said second protrusion structure being opposite the first protrusion structure and including a first plurality of symmetrical protrusion units, each of the first plurality of symmetrical protrusion units having a symmetrical structure about a horizontal or about a vertical axis, the first plurality of symmetrical protrusion units having a height smaller than a wavelength of the first plurality of light rays or the portion of the first plurality of the light rays so as to increase a transmittance of light rays incident on the optical layer. a light emitting unit (110; 210; 310; 410; 510; 610-1, 610-2) configured to emit a first plurality of light rays; a light receiving unit (120; 220; 320; 420; 520; 620-1, 620-2) configured to receive a second plurality of light rays, wherein the second plurality of light rays includes a portion of the first plurality of light rays reflected by a body of a user; wherein the light emitting unit (110; 210; 310; 410; 510; 610-1, 610-2) is arranged in the same plane as the light receiving unit (120; 220; 320; 420; 520; 620-1, 620-2); and an optical layer (130; 230; 330; 430; 530; 630; 1130) placed over the light emitting unit and the light receiving unit having a first surface (11; 21; 31; 51; 61) facing the light emitting unit and the light receiving unit and a second surface (12; 22; 32; 52; 62) opposite the first surface, wherein the optical layer includes: a first protrusion structure (233; 333; 533; 633) formed on the first surface and including a plurality of asymmetrical protrusion units, each of the asymmetrical protrusion units having an asymmetrical structure about a horizontal or about a vertical axis; wherein; the plurality of asymmetrical protrusion units are inclined away from the light receiving unit such that light rays incident on the optical layer are refracted away from the light receiving unit; and a second protrusion structure (131; 531; 631) formed on the second surface, said second protrusion structure being opposite the first protrusion structure and including a first plurality of symmetrical protrusion units, each of the first plurality of symmetrical protrusion units having a symmetrical structure about a horizontal or about a vertical axis, the first plurality of symmetrical protrusion units having a height smaller than a wavelength of the first plurality of light rays or the portion of the first plurality of the light rays so as to increase a transmittance of light rays incident on the optical layer. a first protrusion structure (233; 333; 533; 633) formed on the first surface and including a plurality of asymmetrical protrusion units, each of the asymmetrical protrusion units having an asymmetrical structure about a horizontal or about a vertical axis; wherein; the plurality of asymmetrical protrusion units are inclined away from the light receiving unit such that light rays incident on the optical layer are refracted away from the light receiving unit; and a second protrusion structure (131; 531; 631) formed on the second surface, said second protrusion structure being opposite the first protrusion structure and including a first plurality of symmetrical protrusion units, each of the first plurality of symmetrical protrusion units having a symmetrical structure about a horizontal or about a vertical axis, the first plurality of symmetrical protrusion units having a height smaller than a wavelength of the first plurality of light rays or the portion of the first plurality of the light rays so as to increase a transmittance of light rays incident on the optical layer.