Detectorless 3D terahertz imaging: achieving subwavelength resolution with reflectance confocal interferometric microscopy

Autor: Silva, Jorge, Plöschner, Martin, Bertling, Karl, Ghantala, Mukund, Gillespie, Tim, Torniainen, Jari, Herbert, Jeremy, Lim, Yah Leng, Taimre, Thomas, Qi, Xiaoqiong, Donose, Bogdan C., Zhou, Tao, Lui, Hoi-Shun, Indjin, Dragan, Han, Yingjun, Li, Lianhe, Valavanis, Alexander, Linfield, Edmund H., Davies, A. Giles, Dean, Paul, Rakić, Aleksandar D.
Rok vydání: 2024
Předmět:
Druh dokumentu: Working Paper
Popis: Terahertz imaging holds great potential for non-destructive material inspection, but practical implementation has been limited by resolution constraints. In this study, we present a novel single-pixel THz imaging system based on a confocal microscope architecture, utilising a quantum cascade laser as both transmitter and phase-sensitive receiver. Our approach addresses these challenges by integrating laser feedback interferometry detection, achieving a two-fold improvement in lateral resolution compared to conventional reflectance confocal microscopy and a dramatic enhancement in axial resolution through precise interferometric phase measurements. This breakthrough provides lateral resolution near $\lambda/2$ and a depth of focus better than $\lambda/5$, significantly outperforming traditional confocal systems. The system can produce a 0.5 Mpixel image in under two minutes, surpassing both raster-scanning single-pixel and multipixel focal-plane array-based imagers. Coherent operation enables simultaneous amplitude and phase image acquisition, and a novel visualisation method links amplitude to image saturation and phase to hue, enhancing material characterisation. A 3D tomographic analysis of a silicon chip reveals subwavelength features, demonstrating the system's potential for high-resolution THz imaging and material analysis. This work sets a new benchmark for THz imaging, overcoming key challenges and opening up transformative possibilities for non-destructive material inspection and characterisation.
Databáze: arXiv