Multiple Cavity Square Narrow and Broad Band Optical Filters for Infrared Region Application

In this work, theoretically optimization design of wide and narrow band pass filters have been suggested within middleinfrared region (MIR) that ranged from 9000 nm to 12000 nm. For the numerical calculation, use Germanium (Ge) as the substrate, Zinc sulfide (ZnS) and Cryolite (Na3A1F6) as high and low refractive index respectively. The results shows that, for normal incidence yields the transmittance is high ( T ˃ 99.5 ) at the center of Design wavelength (λo). Also, when the angle of incidence increase, The transmittance of electric polarization decreases and that of magnetic polarization increases , As in the case for the proposed design: Air/(LH)4LHHL(HL)4H(LH)4LHHL(HL)4(HL)4(HL)4HH(LH)4 (LH)4/Ge (TE=96.79) and (TM=99.57) at the angle 30 .