Fabrication of compact polymer waveguide devices using air-trench bends and splitters

A fabrication process for PFCB waveguide air-trench bends and splitters with scanning electron microscope (SEM)-based electron beam lithography (EBL) with alignment accuracy better than 40nm has been developed. High efficiency air-trench bends (97.2% for TE polarization and 96.2% for TM polarization) have been demonstrated. The fabrication of air-trench splitters is challenging because of the small trench width (800nm) and deep and anisotropic trench etch (14.5μm). We have successfully developed a high aspect ratio (18:1) anisotropic PFCB etch using a CO/O
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etch chemistry in an inductively coupled plasma reactive ion etcher (ICP RIE) for PFCB waveguide air-trench splitter fabrication. Using air-trench bends, an ultracompact PFCB arrayed waveguide grating (AWG) 8 x 8 wavelength demultiplexer for Wavelength Division Multiplexing (WDM) application had been designed and fabricated. Compared to a conventional AWG in the same material system, the air-trench bend AWG reduces the area required by a factor of 20.