Firstly, the height of the grating must now be determined. Figure 3(a) presents the transmittance of the -1 diffraction order (-1T) and corresponding resonance angles, as the grating thickness
dg varies from 30 to 300nm. The transmittance and resonance characteristics exhibit strong dependence on the grating thickness. The transmittance of -1 diffraction order rapidly increases first to 61.46% until
dg reaches 100nm, and then it becomes nearly constant. As the thickness exceeds 260nm, a slight decrease in transmittance appears since other diffraction orders become significant. The peak efficiency obtained was
Tmax=65.263% at a thickness of
dg=180nm. Figure 3(b) shows the resonance characteristics for the case of
dg=180nm. Also, the resonance angle increases monotonically with grating thickness as the change in
dg causes the local effective index to increase effectively. Results of approximately 68% of transmittance can be found in the literature for similar systems [
11].