Shinmo An

Fabrication of a 45° microreflector-ended polymer waveguide using one-step UV embossing technique

This paper reports on a fabrication method of 45°-mirror-ended polymer waveguide using single-step UV embossing technique. This technique allows us to fabricate an array of twelve channel multimode polymer waveguides having 45°- mirrors during single-step UV embossing process. For the embossing process we have used a 45°-ended silicon waveguide mold. The silicon waveguide mold has a 45° slope prefabricated at the end of each waveguide structure. With this mold, UV embossing is performed to form undercladding and 45° mirror structures simultaneously. And a metal film is coated on the surface of the 45° slope. And then, core polymer is filled and cured by UV irradiation. By using this method, small size of micro mirror structures can be formed during waveguide fabrication process and fabrication steps can be reduced.

Nanofocusing of light using three-dimensional plasmonic mode conversion.

Efficient nanofocusing of light into a gap plasmon waveguide using three-dimensional mode conversion in a strip plasmonic directional coupler is proposed. Unlike conventional nanofocusing using tapering structures, a plasmonic directional coupler converts E(z)-type odd mode energy into E(y)-type gap plasmon mode by controlling phase mismatch and gap spacing. The simulation result shows the maximum electric field intensity increases up to 58.1 times the input intensity, and 17.3% of the light is focused on the nano gap region.

The effect of KOH and KOH/IPA etching on the surface roughness of the silicon mold to be used for polymer waveguide imprinting

We reports on an experimental result on a wet chemical etching of silicon for the fabrication of a mold template to be used in the embossing of optical waveguide. The silicon wafers we etched with its sidewall inclined to 45° and vertical to the bottom by using the anisotropic etching characteristics of the crystalline silicon. The results show that the surface roughness of the etched (100) and (110) planes is very much dependent on the etching condition such as the etchant concentration and etching temperature. The etched surface roughness is reduced by about 10 times from 34.5nm to 3.05nm in the (100) plane etching by changing the etching condition from 10M KOH solution at 80°C to 18M KOH solution at 40°C. For the (110) plane, the etched roughness is reduced dramatically from 115.75nm to 9.05nm by changing the etching condition from IPA saturated 5M KOH solution at 80°C to 1.25M KOH at 40°C.

Characterization and optimization of residual layer thickness during UV imprint process for singlemode waveguide fabrication

We report on the fabrication and characterization of a residual layer resulting from UV imprinting of singlemode optical waveguide. We have measured the residual thickness formed from the imprinting process for several-um-size singlemode waveguide fabrication using the parameters of the imprinting pressure, dropped volume, and viscosity of the used polymer. We found that the residual layer thickness is dependent on both the initial polymer volume and process pressure and the initial polymer volume is more critical than process pressure. Viscosity of polymer also affects the residual layer thickness, the lowest residual layer thickness of 29nm is achieved with nano-imprinting resin, 0.3uL volume, and imprint pressure more than 20bar. Even with optical resin, the residual layer thickness of 60nm is achieved with 0.3uL volume and imprinting pressure of 30bar.

Design and Fabrication of a Polymer Optical Bench for VCSEL array by UV Embossing

We have designed and fabricated a novel type of polymer based optical bench for vertical-cavity- surface-emitting-laser (VCSEL) array by UV embossing technique. The polymer based optical bench consists of twelve-channel-rectangular grooves as fiber guiding structures and a 45deg-groove as a 90deg-out- of-plane light reflection mirror to guide the light from VCSEL to a multimode fiber (MMF).

Fabrication of a flexible optical printed circuit board (FO-PCB)

We report on the fabrication of a flexible optical interconnection module that has been incorporated as a part of an optical printed circuit board (O-PCB). Optical waveguide arrays are fabricated on flexible polyethylen terephthalate (PET) substrate by UV embossing technology. Electrical layers carrying vertical cavity surface emitted laserdiode (VCSEL) and photodiode (PD) array are attached to the optical layer. We measured optical losses of the flexible waveguide arrays bent over various curvatures and characterized transmission performances of the flexible optical PCB (FO-PCB) module. FO-PCB performed high speed optical interconnection between chips over four waveguide channels up to 7.5Gbps on each.

Fabrication of an optical-electrical printed circuit board (OE-PCB) by double-side lamination of an embedded polymer waveguide board between two electrical printed circuit boards

We designed and fabricated an optical-electrical printed circuit board, which we call OE-PCB, by laminating a board of embedded polymer waveguide arrays between two electrical printed circuit boards. The polymer waveguide arrays are molded by embossing technique using a specially designed silicon mold, which can form the optical waveguide arrays and the 45 degree mirrors concurrently. The integrated silicon molds are fabricated by dry etching or wet etching. The layers of the waveguide arrays are sandwiched and laminated between the upper and the lower electrical PCBs to form the OE-PCBs.

A 10 GBPS Interchip Optical Interconnection Module for Optical Circuit Board Application

We report on fabrication of a 10 Gbps optical interconnection module that can be used as optical printed circuit board (O-PCB) for CPU-and-memory optical interconnection to replace serialized electrical bus signal in a computer system.