Single-scan multiplane phase retrieval with a radiation of terahertz quantum cascade laser

Abstract

Terahertz phase retrieval from a set of axially separated diffractive intensity distributions is a promising single-beam computational imaging technique that ensures the obtention of high spatial resolutions and phase wavefronts, but remains restricted by time-consuming data acquisition processes. In this work, we have adopted an approach, relying on the radiation of a quantum cascade laser and the implementation of an express single-scan measurement of intensity distributions through the continuous on-the-go displacement of a high-sensitivity antenna-coupled microbolometer sensor array. In addition to the simplicity of this practical implementation and the minimization of measurement times, such an approach overcomes the problem of preliminary optimal selections of transverse intensity distributions used in the iterative phase retrieval algorithm and guarantees the required data diversity for high-quality wavefront reconstruction.

Expanding THz Vortex Generation Functionality with Advanced Spiral Zone Plates Based on Single‐Walled Carbon Nanotube Films

“…The iterative procedure of single beam multiple intensity reconstruction (SBMIR) is based on sequential propagation of the field estimate v(x, y, z) between planes, where the measurement of intensities was registered preliminarily. [61][62][63] The calculation of wavefront propagation between data acquisition planes in the Fresnel diffraction zone is carried out using the angular spectrum method. In a discrete the representation, the equation for calculating the field through representation of an angular spectrum of plane waves is described as follows:…”

“…The iterative procedure of single beam multiple intensity reconstruction (SBMIR) is based on sequential propagation of the field estimate v ( x , y , z ) between planes, where the measurement of intensities was registered preliminarily. [ 61–63 ] The calculation of wavefront propagation between data acquisition planes in the Fresnel diffraction zone is carried out using the angular spectrum method. In a discrete the representation, the equation for calculating the field through representation of an angular spectrum of plane waves is described as follows: $$$$\begin{equation} u(x, y, z)=\mathcal {F}^{-1}{\left[\mathcal {F}{\left[u_0{\left(x^{\prime }, y^{\prime }\right)}\right]} \cdot \mathcal {H}{\left(f_x, f_y, \Delta z\right)}\right]} \end{equation}$$$$where u 0 ( x ′, y ′) is the complex field distribution in the initial plane; Δ z is the distance of propagation; $$\mathcal {F}$$ and $$\mathcal {F}^{-1}$$ denote fast forward and inverse Fourier transform operators.…”

Advanced Data Processing For Tomography and 3D Rendering With Terahertz Waves

“…This multiple plane approach is characterized by the extreme simplicity of the object illumination setup and guarantees better convergence compared to single-plane phase retrieval algorithms, but the recording of the diffraction patterns often remains time-consuming. We will present two new algorithms that were investigated namely the algorithm of unordered propagation and the algorithm of data self-extrapolation, abbreviated as SBMIR-U and SBMIR-S correspondingly [4]. The distinctive feature of SBMIR-U is the use of intensity distributions in a stochastic order.…”

“…For SBMIR-S investigation, intensity patterns were employed, cropped to area 4 times smaller than the original size. The corresponding Fresnel numbers have been also reduced by the same factor [4]. In this case unmodified SBMIR have not ensured the convergence.…”

A Novel Triple-Band Terahertz Metamaterial Absorber Using a Stacked Structure of MoS2 and Graphene

“…Research in THz technology has focused on detection, communication, and imaging. Due to the lack of efficient terahertz devices, the rich THz spectrum resources have not been fully exploited and have become a research hotspot in academia [2][3][4][5]. As one of the application devices of the THz system, the THz absorber has also attracted extensive attention from the scientific community and has become a key to promoting the application of THz technology [6,7].…”