Cross-shaped bandpass filters for the near- and mid-infrared wavelength regions.
A photolithographic process has been used to form cross-shaped patterns in 3-μm-thick nickel foils. Patterns with cross arm dimensions in the 10-20-μm range, and with periodicities in the 16-26-μm range, yield self-resonant bandpass filters for wavelengths in the 20-25-μm region. Transmittances as high as 80% were achieved with center wavelength-to-bandwidth ratios (λ(R)/Δλ) of ~5. We present a simple empirical formula that relates the wavelength of peak transmittance, or resonant frequency, with cross dimensions and periodicity.
K D
KD
Möller
J B
JB
Warren
J B
JB
Heaney
C
C
Kotecki