Transmission enhancement in periodic chiral metamaterials with dispersion and gain

The transmission properties are presented for periodic metamaterials composed of dispersive and gain chiral media. Our numerical results predict that for transverse-electric (TE) and transverse-magnetic (TM) incident waves, the co-polarization transmission enhancement can be realized as the transmittance is larger than 0.9. As the parameters of the unit cell are fixed, the multiband of the co-polarization transmission enhancement with broad bandwidth will be obtained for both TE and TM waves as the angle of incidence varies. Meanwhile, the co-polarization transmission enhancement in an ultrawide incident angle range (0 similar to 78 degrees, 0 similar to 86.3 degrees) can be achieved for certain frequencies (35.5 GHz, 35.3 GHz). Furthermore, the co-polarization transmission enhancement for TM waves appears in the whole frequency band (15 similar to 120 GHz) as the angle of incidence satisfies the range of (54.9 degrees similar to 65.9 degrees). Finally, the suitable frequency band and broad bandwidth of the transmission enhancement for both TE and TM waves can be modulated by adjusting the period T and the thickness of chiral layer a. We anticipate that this work offers the opportunity for obtaining broadband and wide-angle transmission enhancement for TE and TM waves, which will shed light on the future design of microwave filters. (C) 2020 Optical Society of America