Efficient fiber-chip coupler based on photonic jet

• An efficient fiber-chip coupler based on photonic jet (PJ) is proposed. • The coupler is composed of a cone embedded in a SiO 2 cuboid. • It works on the basis of mode field compression produced in the PJ formation. • It enables to promote the fiber-chip coupling efficiency from 10 % to 77 %. • It has also merits of large bandwidth, good fabrication tolerance and generality. We report an efficient fiber-chip coupler based on photonic jet (PJ) and operated at 1.55 µm wavelength. The coupler is composed of a micron-sized cone embedded in a SiO 2 cuboid. The device is modeled and the modeling focuses on its coupling performance. The results show that, by aid of the coupler, the coupling efficiency between a single-mode fiber and an on-chip photonic wire (PW) based on LiNbO 3 -on-insulator (LNOI) can be promoted from 10 % to 77 %. The significant promotion of coupling efficiency is related to the substantial mode field compression produced in the PJ formation. Further study shows that the device has a large working bandwidth of 1500–1650 nm for coupling efficiency >75 %, a Fresnel reflection loss of 0.86 dB, a good fabrication tolerance and an acceptable alignment tolerance. The efficient coupling can be also realized for the LNOI PW with other geometries and types. The device is also applicable to on-chip PW based on other platforms, such as SOI and Si 3 N 4 .