We proposed a novel grating design of an out-of-plane coupler with non-uniform duty ratio operating at a wavelength of
1.55 μm for the highly efficient coupling from a waveguide to an optical fiber. In order to evaluate the coupling
performance, the diffracted output beam profile and the focusing performance due to the variations of duty ratio
configuration were investigated by a 2D Bloch-wave analysis. In addition, a simple fabrication method was proposed to
realize the grating by the Near-Field Holographic lithography system with variable aperture unit.
We fabricated an arrayed waveguide grating (AWG) demultiplexer for optical fiber communication systems and
photonic integrated circuits. We also used an embossing technique to fabricated the AWG instead of traditional
semiconductor technologies, such as photolithography and etch process. UV curable polymers (ZPU 12-47 and ZPU 12-
45) were used as the core and upper cladding layers. The polydimethylsiloxane (PDMS) mold used for the embossing
process is manufactured by a photoresist structure formed on a silicon wafer. We tried the embossing onto a fused silica
glass using the PDMS mold. After UV curing, the PDMS mold was peeled away carefully, and a pattern of the AWG
demultiplexer was left on the surface of that substrate. The upper cladding layer was coated over the patterned structure.
The fabrication of the AWG demultiplexer was completed by a cleaving process. The residual layer produced after an
embossing process was adjusted by the volume of polymer droplet. The embossing technique will have the potential for
broad applications in fabrication of photonic devices.
A polymer waveguide grating coupler to vertically couple light between planar waveguide and fiber is proposed and
designed. In order to estimate the coupling performance of the proposed coupler with curved and chirped grating, the
diffraction characteristics of the waveguide grating with a uniform period as an in/out out-of-plane coupler are
investigated. The coupling efficiency and coupling length exhibiting the diffraction characteristics of a uniform
waveguide grating with various structure parameters are calculated based on Bloch-wave analysis. With the optimized
structure parameters showing the high coupling performance, the overall coupling efficiency of the polymer waveguide
grating coupler is obtained by introducing 2D Bloch-wave analysis-based local linear grating model. The calculated
overall coupling efficiency of the coupler is determined to be approximately 30%.