Terahertz Frequency Spreading Filter via One-dimensional Dielectric Multilayer Structures

Theoretical study on the generation of THz sub-comb via surface-emitted optical rectification of ultra-short pulse in periodically poled lithium niobate

“…Similar to the "coarse THz comb" [5], the mechanism of this surface-emitted THz sub-comb generation can be explained by interference. According to figure 3, THz wave generated from a PPLN is a series of THz pulses.…”

“…g THz = -cos n n n θ Δ (5) here Δn is the mismatch of refractive index, θ is the angle between the observation direction R and the x-axis. In surface-emitted geometry (θ = 90°), Δn = n g = 2.3, which is a constant and independent of dispersion of refractive index n THz in THz region.…”

“…Thus it is called coarse THz comb or THz sub-comb. It has been reported that the transmitted spectrum of a THz pulse through a multilayer filter is a sub-comb structure [5]. The main characteristic of this THz spectrum is attributed to THz pulses bouncing back and forth via multilayer structures.…”

THz Filter Using the Transverse-electric (TE1) Mode of the Parallel-plate Waveguide

“…The lowest-order TE1 mode of the PPWG can be used as a high-pass filter, however, because the THz wave is totally absorbed below the cutoff frequency. Recently, a THz spreading filter has been reported using one-dimensional dielectric multilayer structures [13], however, a THz filter for a freely propagating THz beam has not been reported. In this study, TEM and higher TM modes were generated via perpendicular polarization between the incident THz beam and PPWG.…”