| Popis: |
LIGA technology has been used to fabricate linear gratings having free-standing nickel walls a few micrometers wide and as much as 50 micrometers high and period on the order of 10 micrometers . With additional MEMS processing steps, such as devices are intended for use in a tunable infrared filter. Prediction of optical performance is a particularly challenging problem for gratings with these parameters and materials and requires a robust Maxwell solver. We have applied our own code, described elsewhere, in the form of a finite element implementation of equivalent variational problem to examine the optical properties of this class of gratings. Here, we describe our predicted results for transmittance as a function of wavelength and polarization for various grating parameters and incident conditions. Measurements of fabricated gratings were also carried out, and the predictions are shown to agree well with the measured data. The filter cutoff is shown to be sensitive to cone angle of the incident radiation, and the implications of this effect on system performance are discussed. |
