Approaching real‐time terahertz imaging with photo‐induced coded apertures and compressed sensing

Shams, Md. Itrat Bin; Jiang, Zhou; Rahman, Seikh Mohammad Habibur; Qayyum, Jubaid Abdul; Cheng, Li-Jing; Xing, Huili Grace; Fay, Patrick; Liu, L.

doi:10.1049/el.2014.0993

Cited by 33 publications

(11 citation statements)

References 14 publications

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“…Several modulation methods based on the opticallyinduced physical processes in semiconductors are proposed so far 7,[13][14][15][16][17][18] . In particular, pure Si and GaAs crystals have been used for this purpose 15 .…”

mentioning

confidence: 99%

Impurity-induced modulation of terahertz waves in optically excited GaAs

et al. 2017

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The effect of the photoinduced absorption of terahertz (THz) radiation in a semi-insulating GaAs crystal is studied by the pulsed THz transmission spectroscopy. We found that a broad-band modulation of THz radiation may be induced by a low-power optical excitation in the spectral range of the impurity absorption band in GaAs. The measured modulation factor achieves 80%. The amplitude and frequency characteristics of the resulting THz modulator are critically dependent on the carrier density and relaxation dynamics in the conduction band of GaAs. In semi-insulating GaAs crystals, the carrier density created by the impurity excitation is controlled by the rate of their relaxation to the impurity centers. The relaxation rate and, consequently, the frequency characteristics of the modulator can be optimized by an appropriate choice of the impurities and their concentrations. The modulation parameters can be also controlled by the crystal temperature and by the power and photon energy of the optical excitation. These experiments pave the way to the low-power fast optically-controlled THz modulation, imaging, and beam steering.

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confidence: 99%

Impurity-induced modulation of terahertz waves in optically excited GaAs

et al. 2017

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“…In 2008, Chan et al [7] adopted standard printed circuit boards as the random matrix to modulate the terahertz transmission, and demonstrated a THz single-pixel imaging by further combining the compressed sensing (CS) algorithm. In order to avoid the use of moving masks, which are difficult to align, Watts et al [8] made use of a metamaterial spatial modulator, Sensale-Rodriguez et al [9] employed arrays of graphene electro-absorption modulators, and Kannegulla et al [10] and Shams et al [11] demonstrated photo-induced coded-aperture imaging using a semiconductor illuminated by a commercial available digital light processing projector. Recently, silicon wafers have been widely used as THz photomodulators, based on which Stantchev et al [12,13] demonstrated THz superresolution imaging.…”

Section: Introductionmentioning

confidence: 99%

“…When the laser spot reflected by the DMD is changed from black to white, the THz transmittance through the passivated silicon decreases from a high level to a low level, i.e., from "1" to "0". For terahertz single-pixel imaging based on compressed sensing (CS) approach [7,11,21], the target, such as a cartwheel patterned in a gold film, is deposited on top of the front SiO 2 layer. For a THz image of N × N pixels to be measured, a series of masks are projected onto the target.…”

Section: Introductionmentioning

confidence: 99%

Terahertz Single-Pixel Imaging Improved by Using Silicon Wafer with SiO2 Passivation

et al. 2020

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We demonstrate terahertz single-pixel imaging is improved by using a photomodulator based on silicon passivated with SiO 2 . By exploring various SiO 2 thicknesses, we show that the modulation factor of the as-fabricated terahertz photomodulator can reach 0.9, three times that based on bare silicon. This improvement originates from chemical passivation, as well as anti-reflection. Single-pixel imaging experiments based on the compressed sensing method show that reconstructed images adopting the new photomodulator have better quality than the conventional terahertz modulator based on bare silicon. Since the passivation process is routine and low cost, we expect this work will reduce the cost of terahertz photomodulator and single-pixel THz imaging, and advance their applications.

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“…Nevertheless, those systems are still quite large to get a sufficient resolution. Lately, pixels working around 300 GHz [11,12] have been developed and seem promising to reduce SWAP-C. One can overcome the technological difficulty of getting a high-resolution array of subTHz sensors by using a single-pixel camera with a coded aperture instead [13]. A full passive imaging system has been tested [14] with a dual-polarization W-band (75 to 110 GHz) radiometer.…”

Section: Introductionmentioning

confidence: 99%

Modeling of an active terahertz imaging system in brownout conditions

Prophete¹,

Pierrat²,

Sik³

et al. 2018

Appl. Opt.

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We present a theoretical evaluation of a subterahertz (subTHz) system to image through a scattering medium composed of scatterers of sizes close to the wavelength. We specifically study the case of sand grain clouds created by helicopter rotor airflow during landing in arid areas. The different powers received by one pixel of a matrix made of subTHz sensors are identified. Photometric and antenna-based sensors are considered. Besides the thermal contribution to the noise, we focus our attention on the radiation backscattered by the brownout. It appears that a configuration where the source and the camera are distant is the most promising configuration and is realistic for embedded systems.

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Approaching real‐time terahertz imaging with photo‐induced coded apertures and compressed sensing

Cited by 33 publications

References 14 publications

Impurity-induced modulation of terahertz waves in optically excited GaAs

Impurity-induced modulation of terahertz waves in optically excited GaAs

Terahertz Single-Pixel Imaging Improved by Using Silicon Wafer with SiO2 Passivation

Modeling of an active terahertz imaging system in brownout conditions

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