Terahertz Wideband Filter Based on Sub-Wavelength Binary Simple Periodic Structure

Round 1

Reviewer 1 Report

Silicon-based terahertz wideband filter is designed using binary optical vector theory to achieve high diffraction efficiency and wideband filtering performance. The design parameters of the filter are investigated in detail. My detailed comments on this work are as follows:

(1) Please update the introduction by providing the  references regarding metamaterial based filters, SCSRR based and so on. authors may take help from the following:

Temporal and Spatial Dispersion Engineering Using Metamaterial Concepts and Structures,

Bandwidth Enhancement and Frequency Scanning Array Antenna Using Novel UWB Filter Integration Technique for OFDM UWB Radar Applications in Wireless Vital Signs Monitoring

A compact tri‐band bandpass filter utilizing double mode resonator with 6 transmission zeros

Co-designed CPS UWB filter-antenna system

(2) Fig. 2 text is overlapping, please modify it.

(3) Fig. 4 also shows text overlapping please modify and double check it thouroughly.

(4) Provide comparison table at the end showing the performance enhancement of your work over other state of the arts published.

(5) Equation (1) to (4) are an invalid format. modify it accordingly and if taken from literature then provide reference for it as well....

(6) "The frequency range of incident terahertz wave is from 1.66THz to 8.40THz, and a wave of TE
111 polarization is perpendicularly incident," Why TE?

(7)  "Combined  genetic algorithm optimization"  combine with filtering effect? If it is so then how you combine it. Please elaborate it clearly and explain it in the manuscript.

(8) "Compared with DCF, the highest transmittance is increased to 47% from 37%", Specific reason behind this improvement?

(9) It is obvious that the grating period has a significant influence on the 3 dB bandwidth of the THz filter... You are claiming it from simulation or any theory behind it?

(10) Make the traces of Fig. 7 to 09 thicker and increase the font size in order to be visible and understandable....

Major revision is recommended.... 

Author Response

1) Please update the introduction by providing the  references regarding metamaterial based filters, SCSRR based and so on. authors may take help from the following:

Temporal and Spatial Dispersion Engineering Using Metamaterial Concepts and Structures,

Bandwidth Enhancement and Frequency Scanning Array Antenna Using Novel UWB Filter Integration Technique for OFDM UWB Radar Applications in Wireless Vital Signs Monitoring

A compact tri‐band bandpass filter utilizing double mode resonator with 6 transmission zeros

Co-designed CPS UWB filter-antenna system

Reply:The meta-material terahertz filter has become the most popular research, due to its diversity of materials, and broadband filters with excellent performance, with high working frequency and broad 3-dB bandwidth. However, due to its complicated structure, it is difficult to manufacture, therefore it is rare to make such a structure.In 2000, I. H. Libon, P. Dawson et al. [6] illuminate the hybrid quantum well structure by laser, thereby achieving the combination of holes and electrons and generating photons.This in turn changes the number of carriers in the structure. In 2011, Singapore National University et al. [7] used a flexible substrate to achieve broadband filtering effect, using polyethylene naphthalate (PEN) as a substrate, overlapping the multi-layer loop structure, and fabricated a broadband filter. In 2011, Singapore National University et al. [7] used a flexible substrate to achieve broadband filtering effect, using polyethylene naphthalate (PEN) as a substrate, overlapping the multi-layer loop structure, and fabricated a broadband filter.

 

(2) Fig. 2 text is overlapping, please modify it.

Corrected

(3) Fig. 4 also shows text overlapping please modify and double check it thouroughly.

Corrected

(4) Provide comparison table at the end showing the performance enhancement of your work over other state of the arts published.

Reply: Our work increases bandwidth by 0.13THz and efficiency by nearly 14% compared with the current best broadband terahertz filter.

wideband filter	3-dB bandwidth	Maximum transmittance in the   main lobe
DCF	2.20THz	37.0%
Our work	2.33THz	50.9%

 

(5) Equation (1) to (4) are an invalid format. modify it accordingly and if taken from literature then provide reference for it as well....

Corrected

 (6) "The frequency range of incident terahertz wave is from 1.66THz to 8.40THz, and a wave of TE
111 polarization is perpendicularly incident," Why TE?

Reply:Ordinary terahertz source is polarized light, and sub-wavelength devices are related to the polarization of incident light. In this paper, for simplicity, we take TE incident light as an example.

(7)  "Combined  genetic algorithm optimization"  combine with filtering effect? If it is so then how you combine it. Please elaborate it clearly and explain it in the manuscript.

Reply:Through actual optimization, we set the Stall generation, coding method, Crossover function, Scaling function, Generation, Hybird function, etc. Before the optimization starts, The fitness of the corresponding target environment of each individual in the initial population is obtained. By Finding the individual with the highest fitness in the population as the optimal individual in the population, the optimal design result searched by the genetic optimization algorithm is obtained. At the same time, the genetic optimization algorithm is very simple, adaptable, robust, and can process optimization results in parallel, and the convergence speed is quite fast.

(8) "Compared with DCF, the highest transmittance is increased to 47% from 37%", Specific reason behind this improvement?

Reply:DCF is a THz filter with multilayer structure of metamaterial. Due to the absorption of incident light and multilayer reflection of materials, the efficiency of DCF is relatively low. We use dielectric simple periodic grating structure, which has almost no absorption and high transmission characteristics.

(9) It is obvious that the grating period has a significant influence on the 3 dB bandwidth of the THz filter... You are claiming it from simulation or any theory behind it?

Reply:It can be seen from the graph that the sharp decrease of the right shift of the period is due to the guided mode resonance. The incident light produces total reflection in the period, and the efficiency decreases rapidly.

(10) Make the traces of Fig. 7 to 09 thicker and increase the font size in order to be visible and understandable....

Corrected

Author Response File: Author Response.docx

Reviewer 2 Report

In this paper, a silicon-based terahertz wideband filter is designed by using binary optical 10 vector theory to achieve high diffraction efficiency and wideband filtering performance. I have the following comments.

a) In several places the manuscript should be rewritten. For example, Eq. (1) is presented long after introduced in the main text.

b) Please provide a motivation of the cost function in Eq. (4)

c) Authors claim that they use a genetic algorithm to deduce the optimal filter response. Please provide more details to this end;

Author Response

a) In several places the manuscript should be rewritten. For example, Eq. (1) is presented long after introduced in the main text.

Corrected

b) Please provide a motivation of the cost function in Eq. (4)

Reply:M is for high efficiency, N is for low sideband efficiency. When the minimum value of the whole formula is obtained, the device we get is the high efficiency bandpass in the equalization filter section and the high efficiency bandstop in the sideband.

c) Authors claim that they use a genetic algorithm to deduce the optimal filter response. Please provide more details to this end;

Reply:Through actual optimization, we set the Stall generation, coding method, Crossover function, Scaling function, Generation, Hybird function, etc. Before the optimization starts, The fitness of the corresponding target environment of each individual in the initial population is obtained. By Finding the individual with the highest fitness in the population as the optimal individual in the population, the optimal design result searched by the genetic optimization algorithm is obtained. At the same time, the genetic optimization algorithm is very simple, adaptable, robust, and can process optimization results in parallel, and the convergence speed is quite fast.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Thanks for providing the revised version....Some minor revisions are still needed before the manuscript go for publication....

As recommended, update the literature so that reader may understand the background well...Authors have added line 34 to 38, which is not sufficient....I recommended to update with further references....

 Figure 3, Please update the text size to make it visible....Also do it for figure 5(a) and (b) as well...

Figure 8 and 9 are distorted, update it and improve its quality....

Author Response

(1)As recommended, update the literature so that reader may understand the background well...Authors have added line 34 to 38, which is not sufficient....I recommended to update with further references....

Reply:In 2017,Muhib Ur Rahman et al. present a compact tri-band BPF with high skirt selectivity by utilizing double-mode resonator. The filter utilizes 2 sets of resonators instead of conventional 3 sets of resonators for 3 passbands. Two transmission zeros are introduced on each side of the passband, and overall 6 transmission zeros have been constructed which make the passband highly selective[5]. In 2018, MuhibUr Rahman present that a fan beam array antenna utilizing a grounded coplanar waveguide (GCPW) radiating element, CPW feed line,and the grounded reflector is developed for WiMAX applications. A miniaturized wide-band bandpass filter is developed using SCSRR (Semi-Complementary Split Ring Resonator) and DGS (Defective Ground Structures) operating at the 3–8 GHz frequency band[6].

Increase References

5.  MuhibUr Rahman; Dong-Sik Ko; Jung-Dong Park. A compact tri-band bandpass filter utilizing double mode resonator with 6 transmission zeros. Microwave and Optical Technology Letters[J].2017, 10.1002.

6.  MuhibUr Rahman; Mahdi NaghshvarianJahromi; Seyed Sajad Mirjavadi; Abdel Magid Hamouda. Bandwidth Enhancement and Frequency Scanning Array Antenna Using Novel UWB Filter Integration Technique for OFDM UWB Radar Applications in Wireless Vital Signs Monitoring. Sensors[J].2018, 18, 3155.

 (2)Figure 3, Please update the text size to make it visible....Also do it for figure 5(a) and (b) as well...

Corrected

(3)Figure 8 and 9 are distorted, update it and improve its quality....

Corrected

Reviewer 2 Report

All my comments have been addressed in a sufficient manner

Author Response

Thank you for your positive comments.