TY - JOUR
T1 - Record-high positive refractive index change in bismuth germanate crystals through ultrafast laser enhanced polarizability
AU - Fernandez, T. Toney
AU - Privat, Karen
AU - Withford, Michael J.
AU - Gross, Simon
N1 - Copyright © 2020 The Author(s). Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.
PY - 2020/9/15
Y1 - 2020/9/15
N2 - Unlike other crystals, the counter intuitive response of bismuth germanate crystals (Bi4Ge3O12, BGO) to form localized high refractive index contrast waveguides upon ultrafast laser irradiation is explained for the first time. While the waveguide formation is a result of a stoichiometric reorganization of germanium and oxygen, the origin of positive index stems from the formation of highly polarisable non-bridging oxygen complexes. Micro-reflectivity measurements revealed a record-high positive refractive index contrast of 4.25 × 10-2. The currently accepted view that index changes > 1 × 10-2 could be brought about only by engaging heavy metal elements is strongly challenged by this report. The combination of a nearly perfect step-index profile, record-high refractive index contrast, easily tunable waveguide dimensions, and the intrinsic high optical non-linearity, electro-optic activity and optical transparency up to 5.5μm of BGO make these waveguides a highly attractive platform for compact 3D integrated optics.
AB - Unlike other crystals, the counter intuitive response of bismuth germanate crystals (Bi4Ge3O12, BGO) to form localized high refractive index contrast waveguides upon ultrafast laser irradiation is explained for the first time. While the waveguide formation is a result of a stoichiometric reorganization of germanium and oxygen, the origin of positive index stems from the formation of highly polarisable non-bridging oxygen complexes. Micro-reflectivity measurements revealed a record-high positive refractive index contrast of 4.25 × 10-2. The currently accepted view that index changes > 1 × 10-2 could be brought about only by engaging heavy metal elements is strongly challenged by this report. The combination of a nearly perfect step-index profile, record-high refractive index contrast, easily tunable waveguide dimensions, and the intrinsic high optical non-linearity, electro-optic activity and optical transparency up to 5.5μm of BGO make these waveguides a highly attractive platform for compact 3D integrated optics.
UR - http://www.scopus.com/inward/record.url?scp=85091054074&partnerID=8YFLogxK
UR - http://purl.org/au-research/grants/arc/DP170104644
UR - http://purl.org/au-research/grants/arc/DE160100714
U2 - 10.1038/s41598-020-72234-w
DO - 10.1038/s41598-020-72234-w
M3 - Article
C2 - 32934325
AN - SCOPUS:85091054074
SN - 2045-2322
VL - 10
SP - 1
EP - 8
JO - Scientific Reports
JF - Scientific Reports
IS - 1
M1 - 15142
ER -