Coded-Aperture Imaging Using Photo-Induced Reconfigurable Aperture Arrays for Mapping Terahertz Beams

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

doi:10.1109/tthz.2014.2307163

Cited by 50 publications

(20 citation statements)

References 21 publications

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“…In general, a higher modulation depth of THz waves can be achieved by using a longer optical wavelength for photo-excitation. A 550-nm optical illumination is chosen for all the analyses in this article because the Digital Light Processing (DLP) projector used in our prior experimental studies has a peak wavelength of about 550nm [12].…”

Section: Effect Of Optical Illumination Wavelengthmentioning

confidence: 99%

“…In recent years, several methods have been demonstrated to advance the technology for THz wave modulation [9,10]. Among them, THz modulation through photo-induced carriers on a semiconductor using Digital Light Processing (DLP) projector is considered as a high-performance, reconfigurable and cost-effective approach [11,12]. This technique takes the advantages of optically generated conductive patterns on semiconductor substrates (e.g., silicon) to manipulate the transmission of THz waves, allowing one to perform a variety of reconfigurable functions, including THz beam steering [13], polarization, focusing and THz resonators.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Photo-induced spatial modulation of THz waves: opportunities and limitations

Kannegulla¹,

Shams²,

Liu³

et al. 2015

Opt. Express

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Programmable conductive patterns created by photoexcitation of semiconductor substrates using digital light processing (DLP) provides a versatile approach for spatial and temporal modulation of THz waves. The reconfigurable nature of the technology has great potential in implementing several promising THz applications, such as THz beam steering, THz imaging or THz remote sensing, in a simple, cost-effective manner. In this paper, we provide physical insight about how the semiconducting materials, substrate dimension, optical illumination wavelength and illumination size impact the performance of THz modulation, including modulation depth, modulation speed and spatial resolution. The analysis establishes design guidelines for the development of photo-induced THz modulation technology. Evolved from the theoretical analysis, a new mesa array technology composed by a matrix of sub-THz wavelength structures is introduced to maximize both spatial resolution and modulation depth for THz modulation with low-power photoexcitation by prohibiting the lateral diffusion of photogenerated carriers.

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Section: Effect Of Optical Illumination Wavelengthmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Photo-induced spatial modulation of THz waves: opportunities and limitations

Kannegulla¹,

Shams²,

Liu³

et al. 2015

Opt. Express

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“…Chernomyrdin et al 81 have achieved promising resolution enhancement by utilizing solid immersion imaging and wide-aperture spherical lens. 82 In another trend, for the enhancement of the imaging systems, subwavelength focusing using hyperbolic meta materials is proposed by Kannegulla et al [83][84][85] However, as it will be discussed in this paper, GaN-based devices can fundamentally address the resolution by enabling THz imaging systems with frequencies higher than 5 THz and enhancing the photon intensity. For instance, GaN-based quantum-cascade lasers (QCL) can operate in 5 to 12 THz, 86 whereas the operation of conventional naturally cooled GaAs-based QCLs in the upper THz frequency band is limited by longitudinal-optical (LO) phonon of 36 meV.…”

Section: Introductionmentioning

confidence: 97%

Review of GaN-based devices for terahertz operation

Ahi

2017

Opt. Eng

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Abstract. GaN provides the highest electron saturation velocity, breakdown voltage, operation temperature, and thus the highest combined frequency-power performance among commonly used semiconductors. The industrial need for compact, economical, high-resolution, and high-power terahertz (THz) imaging and spectroscopy systems are promoting the utilization of GaN for implementing the next generation of THz systems. As it is reviewed, the mentioned characteristics of GaN together with its capabilities of providing high two-dimensional election densities and large longitudinal optical phonon of ∼90 meV make it one of the most promising semiconductor materials for the future of the THz emitters, detectors, mixers, and frequency multiplicators. GaNbased devices have shown capabilities of operation in the upper THz frequency band of 5 to 12 THz with relatively high photon densities in room temperature. As a result, THz imaging and spectroscopy systems with high resolution and deep depth of penetration can be realized through utilizing GaN-based devices. A comprehensive review of the history and the state of the art of GaN-based electronic devices, including plasma heterostructure field-effect transistors, negative differential resistances, hetero-dimensional Schottky diodes, impact avalanche transit times, quantum-cascade lasers, high electron mobility transistors, Gunn diodes, and tera field-effect transistors together with their impact on the future of THz imaging and spectroscopy systems is provided.

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“…[ 11,19,20 ] Furthermore, bare Si‐based STM for real‐time THz imaging was successfully implemented by Liu et al in combination with programmable illumination from a digital light processing projector (DLP). [ 20,21 ]…”

Section: Introductionmentioning

confidence: 99%

High‐Performance Photo‐Induced Spatial Terahertz Modulator Based on Micropyramid Silicon Array

Wen

Yang

et al. 2020

Adv Materials Technologies

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Reconfigurable conductive pattern created by photoexcitation of high‐resistivity semiconductor provides a powerful approach to realize broadband spatial terahertz modulators (STM), which are highly demanded for constructing cost‐effective and compact terahertz (THz) system. Here a high performance all‐optical STM is proposed and realized based on silicon micropyramid arrays (Si‐MPA), which not only enhances the light harvesting across a broad wavelength range, but also greatly increases the active area for THz modulation. Upon illuminating the Si‐MPA by light with various wavelengths, modulation depth (MD) of four times larger than that of bare silicon is achieved. A maximum MD of 93.8% is obtained under 638 nm laser with a low power density of 1 W cm−2. Reconfigurable THz imaging system based on the Si‐MPA modulator and a single‐element detector is constructed, with which precise THz beam mapping and fast real‐time imaging with 225 pixels are demonstrated. This Si‐MPA‐based STM with large MD at low illumination power density is promising for many THz applications including imaging, beam shaping, holographic projection, etc.

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Coded-Aperture Imaging Using Photo-Induced Reconfigurable Aperture Arrays for Mapping Terahertz Beams

Cited by 50 publications

References 21 publications

Photo-induced spatial modulation of THz waves: opportunities and limitations

Photo-induced spatial modulation of THz waves: opportunities and limitations

Review of GaN-based devices for terahertz operation

High‐Performance Photo‐Induced Spatial Terahertz Modulator Based on Micropyramid Silicon Array

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