  This paper presents a novel method to fabricate the horizontal frustum
structure as a planar optical waveguide by using the proximity printing
technique. A horizontal frustum optical waveguide with a both lateral and
vertical taper structure was produced. The orthogonal and inclined masks with
the diffraction effect were employed in lithography process. This method can
precisely control each horizontal frustum optical waveguide geometric profile
in the fabrication process. The horizontal frustum optical waveguide and its
array with the same inclined angle were generated. The beam propagation
simulation software (BPM_CAD) was used to modeling the optical performance. The
simulation results reveal that the mode profile matched into horizontal frustum
optical waveguide and fiber from the laser diode. The optical loss of
horizontal hemi-frustum structure of optical waveguides was less than 0.2dB.
The horizontal hemifrustum waveguide will be used for fiber coupling on boards
for further optical communication systems.
