Open AccessGradient-index optical fiber lens for efficient fiber-to-chip coupling
Author(s) -
Henrik Melkonyan,
Kenaish Al Qubaisi,
Karen Sloyan,
Anatol Khilo,
Marcus S. Dahlem
Publication year - 2017
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.25.013035
Subject(s) - materials science , optics , graded index fiber , lens (geology) , mode volume , optical fiber , refractive index , single mode optical fiber , fiber , plastic optical fiber , polarization maintaining optical fiber , dispersion shifted fiber , photonic crystal fiber , gradient index optics , fiber optic sensor , optoelectronics , wavelength , physics , composite material
A gradient-index optical fiber lens is proposed and fabricated on the tip of a single-mode fiber using focused ion beam milling. Second-order effective medium theory is used to design a gradual change in the fill factor, which ensures a parabolic effective refractive index distribution. The proposed fiber lens design is simulated via the three-dimensional finite-difference time-domain method, and demonstrated through confocal optical measurements. At a wavelength of 1550 nm, the fabricated lenses focus a 10.4 μm mode field diameter exiting the fiber into spot sizes between 3-5 μm, located 4-6 μm away from the fiber tip. Direct coupling into a silicon-on-insulator chip is also demonstrated, where the fabricated gradient-index lens has a coupling efficiency comparable to a commercial lensed fiber.