Fig. 1. (a) Schematic of the all-dielectric fiber-tip lens. (b) The effective refractive index of a single resonator as a function of the width of silicon. Phase distributions of the resonators with the silicon widths of (c) 500 nm and (d) 600 nm. (e) The changes of the phase delay and transmittance of the resonator as a function of the width of silicon. The width of the silicon resonators of the optimized fiber-tip lens is chosen between two black dotted lines.

Fig. 2. (a) Phase distributions for different focal lengths (1300 nm). (b) The field intensity distribution of the fiber-tip lens with the focal length of ∼309 μm. The color bar indicates the electric field intensity. (c) Normalized electric field intensity distribution of the fiber-tip lens along the x axis at the focal plane (y=309μm). The FWHM is 9.0 μm.

Fig. 3. Change of focal lengths of the fiber lens for different temperatures.

Fig. 4. Normalized electric field intensity distributions of the fiber-tip lens (a) along the y direction (x=0μm) and (b) along the x axis at the focal length for different temperatures. (c) The focusing efficiency of the fiber-tip lens.