Optically controlled terahertz beam steering and imaging

Busch, Stefan; Scherger, Benedikt; Scheller, Maik; Koch, Martin

doi:10.1364/ol.37.001391

Cited by 103 publications

(58 citation statements)

References 17 publications

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“…Another option therefore is to alter the imaging paradigm itself, relying on the sparsity of spatial frequencies in most images to perform compressed sensing (CS). First demonstrated at THz frequencies in 2008 (47,48) this technique has since been demonstrated, among others, by using either random mechanically developed and switched masks (49), a spinning disk set (50), electrically gated graphene modulator arrays (51) and by photoexciting a silicon substrate with an optical pattern (52). The techniques demonstrated here rely on a binary state for each pixel, i.e., the pixels are either on and off, in order to eventually separate the response of each pixel through the linear combinations recorded in the measurements.…”

Section: Imaging Speedmentioning

confidence: 99%

Recent advances in terahertz technology for biomedical applications

Sun¹,

He²,

Li³

et al. 2017

Quant. Imaging Med. Surg.

230

113

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Terahertz instrumentation has improved significantly in recent years such that THz imaging systems have become more affordable and easier to use. THz systems can now be operated by non-THz experts greatly facilitating research into many potential applications. Due to the non-ionising nature of THz light and its high sensitivity to soft tissues, there is an increasing interest in biomedical applications including both in vivo and ex vivo studies. Additionally, research continues into understanding the origin of contrast and how to interpret terahertz biomedical images. This short review highlights some of the recent work in these areas and suggests some future research directions.

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Section: Imaging Speedmentioning

confidence: 99%

Recent advances in terahertz technology for biomedical applications

Sun¹,

He²,

Li³

et al. 2017

Quant. Imaging Med. Surg.

230

113

View full text Add to dashboard Cite

show abstract

“…A more flexible approach is to start with a homogeneous substrate into which the photonic structure is all-optically imprinted, [18][19][20][21] for example, using the scheme presented in Figure 1a. Here, a laser beam with a spatially modulated cross-section is incident to a plane substrate, in which the optical intensity pattern is translated into a spatial modulation of the refractive index.…”

Section: Introductionmentioning

confidence: 99%

Subcycle control of terahertz waveform polarization using all-optically induced transient metamaterials

et al. 2014

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Coherent radiation with frequencies ranging from 0.3 to 30 THz has recently become accessible using femtosecond laser technology. These terahertz (THz) waves have already been applied in spectroscopy and imaging and can be manipulated using static optical elements such as lenses, polarizers and filters. However, ultrafast modulation of THz radiation is required as well, for instance, in short-range wireless communication or for preparing shaped THz transients for the coherent control of numerous material excitations. Here, we demonstrate an all-optically created transient metamaterial that allows us to manipulate the polarization of THz waveforms with subcycle switch-on times. The polarization-modulated pulses are potentially interesting for controlling elementary motions such as the vibration of crystal lattices, the rotation of molecules and the precession of spins.

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“…Photo-generated antennas [18] and chiral structures [19] have been recently demonstrated using structured illumination of semiconductors. Also photo-generated gratings [20,21] and controlled THz diffraction has been demonstrated [22,23]. However, none of the previous works has shown an asymmetric scattering or diffraction as we do here, nor relates the results to the rapidly emerging field of metasurfaces.…”

Section: Introductionmentioning

confidence: 54%

Active terahertz beam steering by photo-generated graded index gratings in thin semiconductor films

Steinbusch¹,

Tyagi²,

Schaafsma³

et al. 2014

Opt. Express

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Abstract:We demonstrate active beam steering of terahertz radiation using a photo-excited thin layer of gallium arsenide. A constant gradient of phase discontinuity along the interface is introduced by an spatially inhomogeneous density of free charge carriers that are photo-generated in the GaAs with an optical pump. The optical pump has been spatially modulated to form the shape of a planar blazed grating. The phase gradient leads to an asymmetry between the +1 and -1 transmission diffracted orders of more than a factor two. Optimization of the grating structure can lead to an asymmetry of more than one order of magnitude. Similar to metasurfaces made of plasmonic antennas, the photo-generated grating is a planar structure that can achieve large beam steering efficiency. Moreover, the photo-generation of such structures provides a platform for active THz beam steering.

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Optically controlled terahertz beam steering and imaging

Cited by 103 publications

References 17 publications

Recent advances in terahertz technology for biomedical applications

Recent advances in terahertz technology for biomedical applications

Subcycle control of terahertz waveform polarization using all-optically induced transient metamaterials

Active terahertz beam steering by photo-generated graded index gratings in thin semiconductor films

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