In this paper, we report laboratory test results of an LPG that can maintain a constant resonant peak depth over an
enhanced tuning range when it is coated with an ITO electrode that has optimized thickness and refractive index.
Without the ITO layer, LPG tuning ranges as large as 50 nm have been achieved when the ambient index is
increased from 1.00 (air) to ~1.444 (index of the silica cladding), but the peak depth cannot be maintained. When a
properly designed, high-index ITO overlay is coated onto the silica cladding, mode transition effects coincide with
the LPG's intrinsic sensitivity to changes in the ambient index, resulting in a stable peak depth over an enhanced
tuning range. The authors have experimentally demonstrated an LPG coated with ITO that can be tuned in excess of
150 nm with an ambient refractive index change of less than 0.01. To the best of the authors' knowledge, this is the
highest sensitivity reported for an LPG to date. In addition to the tuning performance, the resonant peak remains
within 1 dB of its maximum depth for at least 100 nm of the tuning range, which allows the tunable LPG to be used
in real applications.