Nb2O5-based Grating Coupler Employing Multiple Nb2O5/SiO2 Layers in Integrated Probe for Cross-Sectional Velocity Distribution Measurement

A grating coupler that employs multiple Nb
2
O
5
/SiO
2
layers is designed to improve the input/output efficiency in the Nb
2
O
5
- based integrated probe for two-dimensional cross-sectional velocity distribution measurements. As the result of simulation, the efficiency was improved by increasing the number of the Nb
2
O
5
/SiO
2
layers over the assumed input/output angles and wavelengths.