Low-loss and broadband fiber-to-chip coupler by 3D fabrication on a silicon photonic platform

Opt Lett. 2020 Mar 1;45(5):1236-1239. doi: 10.1364/OL.386550.

Abstract

We propose and demonstrate a low-loss fiber-to-chip vertical coupler on the silicon photonic platform by using a 3D two-photon fabrication method. Such a coupler significantly reduces insertion loss, measured to be 1 dB, and provides a wide working wavelength range for both TE and TM polarizations over the entire C-band. Moreover, a large tolerance for misalignment of the coupling fiber, up to 4.5 µm for a 1 dB loss, enables the development of relaxed alignment techniques.