A spatial light modulator for terahertz beams

Chan, Wai Lam; Chen, Hou-Tong; Taylor, Antoinette J.; Brener, Igal; Cich, Michael Joseph; Mittleman, Daniel M.

doi:10.1063/1.3147221

Cited by 292 publications

(175 citation statements)

References 16 publications

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“…A good linear relationship between the relative transmission and the control beam intensity is observed within the range from 0 to 100 mJ/cm 2 . Compared with the electrically controlled THz spatial modulator 22 , this optically controlled STM has higher resolution and better modulation depth. To evaluate the resolving power of the STM, a 1951 USAF 1X resolution test chart (Fig.…”

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confidence: 99%

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Spatial Terahertz Modulator

Xie

Wang

et al. 2013

Sci Rep

126

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Terahertz (THz) technology is a developing and promising candidate for biological imaging, security inspection and communications, due to the low photon energy, the high transparency and the broad band properties of the THz radiation 1-3 . However, a major encountered bottleneck is lack of efficient devices to manipulate the THz wave, especially to modulate the THz wave front. A wave front modulator should allow the optical or electrical control of the spatial transmission (or reflection) of an input THz wave and hence the ability to encode the information in a wave front 4 . Here we propose a spatial THz modulator (STM) to dynamically control the THz wave front with photo-generated carriers. A computer generated THz hologram is projected onto a silicon wafer by a conventional spatial light modulator (SLM). The corresponding photo-generated carrier spatial distribution will be induced, which forms an amplitude hologram to modulate the wave front of the input THz beam. Some special intensity patterns and vortex beams are generated by using this method. This all-optical controllable STM is structure free, high resolution and broadband. It is expected to be widely used in future THz imaging and communication systems.S andwiched between the microwave and infrared, THz radiation has been notoriously difficult to produce, modulate and detect [1][2][3] . Recent progresses such as quantum-cascade lasers 5,6 , terahertz wave generation through a nonlinear crystal 7 and THz time-domain spectroscopy 8 are promoting this subject into one of the most rapidly growing fields. High performance devices to control and manipulate the THz radiation are in urgent demand to develop sophisticated imaging and communication system. The filters, absorbers and polarizers based on graphene, frequency selective surface, metamaterials and photonic crystals have been reported [9][10][11][12][13][14][15][16][17][18] . However, the wave front modulation devices are still lacking. Recently, a novel technology based on the metasurface has been demonstrated to generate the desired wave front distribution 19,20 . Unfortunately, the specific function of this kind of devices has been determined at the moment of their design and could not be flexibly changed any more. The SLM which has been widely used in the visible light band can optically or electrically control the spatial transmission (or reflection) of an input light beam and encode information in the wave front 4 . The SLM always plays an important role in optical information processing, three dimensional image display, optical interconnections and real-time beam shaping. Usually, the SLM is realized through liquid crystals, magneto-optic materials or deformable mirrors. However, such mechanisms cannot work well in the THz regime due to the lack of suitable materials and the size mismatching between the micro-machined components and the THz wavelength 21 . In order to obtain the STM, a novel technology needs to be explored.The STM requires an array of small building blocks that can independentl...

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“…al. proposed a multi-pixel spatial modulator for THz beams using active THz metamaterials 22 . The transmission of each unit cell can be independently controlled by applying a small external voltage at room temperature.…”

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confidence: 99%

Spatial Terahertz Modulator

Xie

Wang

et al. 2013

Sci Rep

126

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“…It is also the first to operate at switching voltage of 1 V, and the lowest reported to-date is 14 V. 15 Unlike current solid-state THz SLMs, the embedded HEMT device in every split-gap allows very high speed operation 19 (∼10 MHz), even GHz operation if designed appropriately. We would like to emphasize that since the imaging is effectively done at a single frequency, a commercial THz imaging system can be designed with a more sensitive single-pixel detector and cheaper source, such as a Schottky diode and diode multipliers, which will be much lower power and cost compared to the cw THz spectrometer used in this work.…”

Section: Discussionmentioning

confidence: 99%

“…Recent research has demonstrated THz SLMs using all-electronic dynamic metamaterials used in single-pixel THz imaging systems. 10,15,16 These dynamic metamaterial SLMs are electronically controlled by injecting charges or depleting them in the bulk semiconductor substrate, which is an inherently slow process due to the intrinsically large capacitance of what is essentially a large bulk diode structure. 15,17,18 This results in a slow switching speed and large dynamic power consumption.…”

Section: Introductionmentioning

confidence: 99%

A low-voltage high-speed terahertz spatial light modulator using active metamaterial

Rout

Sonkusale

2016

APL Photonics

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An all solid-state metamaterial based terahertz (THz) spatial light modulator (SLM) is presented which uses high mobility 2DEG to manipulate the metamaterial resonant frequency (0.45 THz) leading to terahertz wave modulation. The 2DEG is created by embedding pseudomorphic high-electron mobility transistors in the capacitive gap of each electrical-LC resonator, allowing the charge density to be controlled with very low voltage (1 V) and modulating speeds up to 10 MHz while consuming sub-milliwatt power. We have demonstrated our SLM as a 2 × 2 pixel array operating around 0.45 THz by raster scanning a 6 × 6 image of an occluded metal object behind a thick polystyrene screen using a single-pixel THz imaging setup.

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“…Established electronic solutions have high energy requirements and complexity as they require conversion between optical and electronic signals, while all-optical techniques enabled by photorefraction are slow. Recently, several metamaterial-based approaches to dynamic spatial control over optical signals have emerged, [6][7][8] including all-optical ones, 9,10 which create interesting possibilities.…”

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A femtosecond Raman generator for long wavelength two-photon and third harmonic generation imaging

et al. 2016

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We demonstrate a femtosecond single pass Raman generator based on an YVO crystal pumped by a high energy fiber laser at a wavelength of 1064 nm and a repetition rate of 1 MHz. The Raman generator shifts the pump wavelength to 1175 nm, in a broad band spectrum, making it suitable for multi-photon microscopy. We use the Raman generator for third harmonic generation imaging of live plant specimens as well as for two-photon fluorescence imaging of red fluorescent protein (RFP) expressing HeLa cells. We demonstrate that the photo-damage to a live specimen is low

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A spatial light modulator for terahertz beams

Cited by 292 publications

References 16 publications

Spatial Terahertz Modulator

Spatial Terahertz Modulator

A low-voltage high-speed terahertz spatial light modulator using active metamaterial

A femtosecond Raman generator for long wavelength two-photon and third harmonic generation imaging

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