24-ch microlens-integrated no-polish connector for optical interconnection with polymer waveguides

Abstract

We successfully developed a new 24-ch optical connector for polymer waveguides. The connector consists of a transparent thermoplastic resin that has two rectangular slits on one side for alignment of the waveguide films and integrated microlens arrays on the other side for coupling to the MT connector. Two 12-ch waveguide films were cut to a 3-mm width. The thickness of each waveguide film was controlled at 100 µm. The waveguide films were inserted into the slits until they touched the bottom face of the slit. Ultraviolet curing adhesive was used to achieve a short hardening process. The expanded beam in the transparent material is focused by the microlens arrays formed on the connector surface. This lens structure enables assembly without the need for a polishing process. We designed the lens for coupling between a step-index 40-μm rectangular waveguide and a graded-index 50-μm fiber. We achieved low-loss optical coupling by designing a method of providing asymmetric magnification between the horizontal and vertical directions in order to compensate for the asymmetric numerical aperture of the waveguide. The typical measured coupling losses from/to the waveguide to/from the fiber were 1.2 dB and 0.6 dB, respectively. The total coupling loss was as small as that of a physical contact connection.

Structure of 25-Gb/s Optical Engine for QSFP Enabling High-Precision Passive Alignment of Optical Assembly

“…The expanded beam in the transparent material is focused by the microlens formed on the connector surface. This lens structure enables assembly without the need for a polishing process [10]. The size of the FPC-OE is 13.5 × 10.6 mm, the length of the waveguide from 45° mirror to the ferrule is 27.8 mm.…”