Terahertz substance imaging by waveform shaping

Yi, Minwoo; Kim, Hyosub; Jin, Kyong Hwan; Ye, Jong Chul; Ahn, Jaewook

doi:10.1364/oe.20.020783

Cited by 6 publications

(3 citation statements)

References 21 publications

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“…The absorption coefficient results show that at low irradiation doses (5 kGy), the absorption of the sample for terahertz does not change significantly, and it decreases significantly when the irradiation dose is larger than 15 kGy, And the absorption of the sample by continuing to increase the radiation dose will not change significantly. 43,44 This indicates that the terahertz absorption property of the irradiation for HMA needs to meet the irradiation dose to reach a certain threshold, and the continued increase of the irradiation dose after denaturation does not obviously affect its properties.…”

Section: Terahertz Analysismentioning

confidence: 99%

Terahertz spectroscopy research on motion‐limited molecular chain of random polymethacrylate

Huang,

Yang,

2023

J of Applied Polymer Sci

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In this study, an innovative method was used to examine the impact of gamma‐ray irradiation on three specific monomers: methyl methacrylate (MMA), hexyl methacrylate (HMA), and lauryl methacrylate (LMA). The primary objective was to produce corresponding polymers—polymethyl methacrylate (PMMA), polyhexyl methacrylate (PHMA), and poly(lauryl methacrylate) (PLMA). The significance of the research was determined by conducting a thorough analysis of the thermal properties and structural characteristics of these polymers using advanced techniques, including thermogravimetric analysis and differential scanning calorimetry (TGA‐DSC), as well as Fourier transform infrared spectroscopy (FTIR). The results indicated that irradiation at a 30 kGy dose caused distinct decomposition of ester groups within the polymer matrices. Additionally, a clear trend was observed in the maximum exothermic temperature among the three polymers, with PMMA exhibiting the lowest temperature, followed by PLMA, and PHMA with the highest temperature. Surprisingly, when the radiation dose exceeded 30 kGy, PHMA's thermal stability peaked, demonstrating remarkable resistance to further changes. This highlights the crucial role of radiation dosage in adjusting polymer thermal properties. Furthermore, analysis of infrared characteristic peaks identified a critical radiation dose range between 15 and 30 kGy, where polymerization was efficiently promoted without generating extra by‐products, showcasing experimental ingenuity. Lastly, optical properties of the synthesized polymers were explored using THz time‐domain spectroscopy. Results showed intriguing changes in refractive indices following 30 kGy dose irradiation. Specifically, MMA and HMA exhibited moderate refractive index increases, while LMA displayed a significant decrease. Notably, PHMA demonstrated substantial absorption reduction beyond 15 kGy doses, with minimal further changes, highlighting the potential to customize polymer optical properties through controlled irradiation.

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Section: Terahertz Analysismentioning

confidence: 99%

Terahertz spectroscopy research on motion‐limited molecular chain of random polymethacrylate

Huang,

Yang,

2023

J of Applied Polymer Sci

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“…where τ is 2 ps for an appropriate bandwidth compatible with the proposed structure and T 0 is set to 8 ps, the same as previously used in Equation (3). As shown in Figures 10a,b, this approach has great accuracy and could replace the full-wave simulation analysis which is very time consuming.…”

Section: E Y =mentioning

confidence: 99%

“…where τ is 2 ps for an appropriate bandwidth compatible with the proposed structure and T 0 is set to 8 ps, the same as previously used in Equation (3).…”

Section: E Y =mentioning

confidence: 99%

Terahertz Waveguide-Based Pulse-Shaper System Analysis and Modeling

Razavizadeh¹,

Sadeghzadeh²,

Kashani³

2021

Preprint

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In this paper, the transfer function of a passive waveguide-based terahertz pulse shaper is achieved using the time domain data provided by the full-wave simulation of the structure. The fractional order of the transfer function is determined based on the time response resulting from an arbitrary excitation of the proposed pulse shaper. The full-wave electromagnetic numerical analyses are applied to attain the time-domain output data of the helical gold-ribbon dielectric-lined waveguide as the terahertz pulse shaper. In order to verify the simulation results, the proposed device has been examined using two different numerical methods which are the Finite Element Method (FEM) and the Finite Integral Technique (FIT). A good agreement was found between the results of FIT and FEM methods. The use of the system transfer function to analyze the structure is preferable to the full-wave simulation because of saving the execution time. Once the transfer function is determined, one could apply it for the subsequent time-domain analysis of the pulse shaper with various inputs.

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