High optical coupling efficiency of polymer microlens and pillar on single mode fiber for silicon photonics

Abstract

Silicon photonics technology has attracted considerable attention these days. However, the low coupling efficiency due to the difference in spot size between silicon photonic (SiPh) chips and single-mode fibers (SMFs) remains a challenging issue. We have already proposed a unique combination of a microlens and a pillar on the facet of SMF. However, the pillar may have difficulty in keeping a single mode for a signal beam of 1. 55 μm wavelength due to air cladding. In this study, we clarified the length of the pillar that can support the single mode through simulations and experiments. By the optimum designing, the spot size as the same level as the SiPh chip was obtained. We could show that our coupling device provides high coupling efficiency with a test sample of SiPh chip, and this device also can be applied to multi-core fibers.

Polymer Spot Size Expanders for High Efficiency Optical Coupling in Optical Interconnection

“…The low efficiency, particularly in the edge coupling scheme, is primarily due to the difference in the spot size of the SiPh chips (3-4 m) and that of SMFs (10 m) [1]. To overcome this problem, researchers have produced coupling devices fabricated on the end face of an SMF [2][3][4][5]. In addition, the connection of SMF and SiPh using a tapered self-written waveguide has been proposed [6][7][8].…”

Polymer tapered pillar on a fiber end fabricated by UV irradiation using a high-NA fiber

“…This difference in spot size is a significant factor in the lower coupling efficiency between them. To achieve high coupling between them, several approaches have been proposed, such as a polymer waveguide with curvature on the SMF core end face [2], polymer microtips at different types of optical fibers [3], a coupling device consisting of a pillar and microlens on the SMF end face [4][5], a self-written waveguide (SWW) using a resin that can be cured in the near-infrared region [6][7], a taper fabricated by 3D printing technology [8], a self-formed tapered waveguide by bilateral injection from a SiPh chip, and an SMF with a special waveguide fabricated [9][10]. Previously, our university team proposed a method for fabricating multiple tapered pillars using the photomask transfer method for UV-curable resin [11].…”