Abstract
We introduce low-loss amorphous titanium dioxide (TiO
$_{2}$
) strip waveguides with sub-wavelength dimensions. The waveguides were fabricated by the combination of
atomic layer deposition (ALD), electron beam lithography (EBL), and reactive ion etching (RIE). Propagation losses of
the strip waveguides were found to be as low as 5.0 dB/cm at 1.55
$\mu$
m wavelength. Those propagation losses are mostly due to the sidewall roughness of the waveguides that is
caused by the lithography process. The propagation losses were further reduced by deposition, on the fabricated strip
waveguides, of an additional layer of TiO
$_{2}$
made by using ALD.
A supplementary layer of TiO
$_{2}$
with a thickness of 30 nm
reduced the measured propagation losses from 5.0
$\pm$
0.5 dB/cm to 2.4
$\pm$
0.2 dB/cm at 1.55
$\mu$
m wavelength. It is due to the fact that, after the
redeposition process, the initial waveguide sidewall, i.e., the TiO
$_{2}$
/air interface, is virtually removed and the new sidewall has a reduced roughness.
© 2013 IEEE
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