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.