Tunable compression of THz chirped pulses using a helical graphene ribbon-loaded hollow-core waveguide

Abstract

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Terahertz waveguide-based pulse-shaper system analysis and modeling

“…Based on the numerically obtained information of group velocity, it is shown in Figure 3a that we obtained the optimal traveling length of L 0 as 579µm. Figure 3a compares the normalized group velocity and the group delay of the proposed structure with those reported in [11]. It is clearly seen that the graphene-based pulse shaper in an equal bandwidth around its center frequency, as shown in Figure 3a, is lower ∆V g than the Au-based one.…”

“…Here, we made a step forward for a passive fixed pulse-shaper by replacing the helical graphene ribbon with a gold ribbon. Compared with our previous work [11], the pulse shape is greatly improved by reducing the pedestal and ringing. Moreover, in order to prove the validity of the numerical analysis, the proposed device has been examined using Finite Element Method (FEM) and the Finite Integral Technique (FIT).…”

“…Fig. 3 (a) Group delay and normalized group velocity extracted from the phase of the transmission coefficient using FIT method for the proposed structure (solid line) and the zero-biased graphene-based structure reported in [11] (dashed line), and (b) the output envelope waveforms of the proposed device based on a chirped-input signal using two different numerical approaches of FIT and FEM, compared with output signal of a zero-biased graphene-based one [11].…”

“…One essential drawback of such structures is bulky size of the pulse shaper (four layers with 3 cm space distance between sequential layers) which is not applicable to incorporation with compact semiconductor terahertz sources. Recently, in our previous work [11], we demonstrated a tunable THz pulse shaping technique utilizing the positive group velocity dispersion (GVD) region of a dielectric-lined circular waveguide loaded with a helical graphene ribbon. The results presented in [11] indicated a feasibility of tunable pulse compression applications by using the graphene ribbon.…”

“…Recently, in our previous work [11], we demonstrated a tunable THz pulse shaping technique utilizing the positive group velocity dispersion (GVD) region of a dielectric-lined circular waveguide loaded with a helical graphene ribbon. The results presented in [11] indicated a feasibility of tunable pulse compression applications by using the graphene ribbon. Here, we made a step forward for a passive fixed pulse-shaper by replacing the helical graphene ribbon with a gold ribbon.…”