Terahertz zone plates with integrated laser‐ablated bandpass filters.

Properties of zone plates with integrated bandpass filters were simulated numerically and demonstrated experimentally for 0.76 THz frequency. Finite‐difference time‐domain simulations were used to predict properties of a conventional zone plate and laser‐ablated zone plate with resonant filter areas. Zone plates were produced employing laser direct writing and characterised by Fourier spectroscopy and an optically pumped terahertz laser. [ABSTRACT FROM AUTHOR]