Polymer Microlens on Pillar Grown From Single-Mode Fiber Core for Silicon Photonics

A novel coupling device composed of a combination of microlens and pillar having an approximately
$8~\mu \text{m}$
diameter and
$20~\mu \text{m}$
height and grown from single-mode fiber (SMF) core end is proposed. This device was successfully fabricated by using a self-written waveguide and dipping method with UV-curable resin. Theoretical and experimental studies were done. A high coupling efficiency of more than −0.97dB was obtained for coupling to an ultrahigh numerical aperture (0.41) SMF with a spot diameter of
$3.7~\mu \text{m}$
at a
$1.55~\mu \text{m}$
wavelength in place of a silicon chip with an integrated spot-size converter. In contrast, it is only −4.0dB by a conventional SMF.