Mid-infrared single-pixel imaging at the single-photon level

Abstract

Single-pixel cameras have recently emerged as promising alternatives to multi-pixel sensors due to reduced costs and superior durability, which are particularly attractive for mid-infrared (MIR) imaging pertinent to applications including industry inspection and biomedical diagnosis. To date, MIR single-pixel photon-sparse imaging has yet been realized, which urgently calls for high-sensitivity optical detectors and high-fidelity spatial modulators. Here, we demonstrate a MIR single-photon computational imaging with a single-element silicon detector. The underlying methodology relies on nonlinear structured detection, where encoded time-varying pump patterns are optically imprinted onto a MIR object image through sum-frequency generation. Simultaneously, the MIR radiation is spectrally translated into the visible region, thus permitting infrared single-photon upconversion detection. Then, the use of advanced algorithms of compressed sensing and deep learning allows us to reconstruct MIR images under sub-Nyquist sampling and photon-starving illumination. The presented paradigm of single-pixel upconversion imaging is featured with single-pixel simplicity, single-photon sensitivity, and room-temperature operation, which would establish a new path for sensitive imaging at longer infrared wavelengths or terahertz frequencies, where high-sensitivity photon counters and high-fidelity spatial modulators are typically hard to access.

Enhanced Asymmetric Light‐Plasmon Coupling in Graphene Nanoribbons for High‐Efficiency Transmissive Infrared Modulation

“…By assuming the time components of S 1+ , S 1‐ , S 2‐ and a in Equation are exp ( ‐iωt ), the resonant transmittance T res = ( n s / n a )∙| S 2‐ / S 1+ | 2 of graphene plasmons can be solved (see Supporting Information for details). Then, by inserting T res and T off into the definition of the modulation efficiency, the following expression is obtained, $$$$\begin{equation}\eta = 1 - \frac{1}{{{{\left( {1 + 4\tau {\gamma }_{asy}} \right)}}^2}},\end{equation}$$$$where $$$$\begin{equation}{\gamma }_{asy} = \frac{{2{n}_a}}{{{n}_a + {n}_s}}\gamma \end{equation}$$$$is the coupling rate between graphene plasmons and the free space light at the asymmetric dielectric environment with n a = 1 being the refractive index of air and n s being the refractive index of the substrate.…”

“…Mid-infrared free-space optical modulators, possessing the ability to regulate the amplitude, phase, and polarization of mid-infrared light, have been recognized as one of the most crucial devices in the fields such as infrared scene projection, infrared deception, infrared optical communication and hyper spectra imaging [1][2][3][4] The traditional digital micromirror based modulator, consisting of an array of individually switchable mirrors, can modulate the mid-infrared light in reflection mode by designing the infrared transparent optical window. [5,6] Nevertheless, due to the reflective geometry of this modulator, it is primarily served as a discrete component in an optoelectronic system and commonly requires extra optical elements such as beam splitters or polarizers to separate the incident and reflected light, making it difficult to shrink the size of the optoelectronic system to the chip level.…”

Computational ghost imaging with adaptive intensity illumination for scenes featuring specular surfaces

“…The image can be retrieved after correlating the speckle patterns with the corresponding light intensity values via a reconstruction algorithm. Benefiting from the low manufacturing cost, wide detection band, and highly sensitive responsiveness of single-pixel detectors, CGI is widely applied in various fields: color imaging [2][3][4], infrared imaging [5][6][7], terahertz imaging [8][9][10], spectral imaging [11][12][13], three-dimensional imaging [14][15][16], and biomedical imaging [17][18][19], etc. However, these works mostly deal with transmissive objects or reflective objects with Lambertian surfaces and rarely target scenarios containing specular surfaces.…”

Mid-infrared single-photon upconversion spectroscopy enabled by nonlocal wavelength-to-time mapping

“…This method has the advantage of eliminating the requirement for both MIR detectors and interferometers, which results in a stable and compact structure. MIR frequency upconversion has been a key technique for MIR spectrometer (25), imaging (26)(27)(28)(29), optical coherence tomography (30), etc. However, in ultrasensitive MIR frequency upconversion, effective signal extraction in complicated and noisy environments remains a pressing concern.…”