Photo-designed terahertz devices

Okada, T.; Tanaka, Kōichiro

doi:10.1038/srep00121

Cited by 55 publications

(52 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…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: Introductioncontrasting

confidence: 49%

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

Steinbusch¹,

Tyagi²,

Schaafsma³

et al. 2014

Opt. Express

View full text Add to dashboard Cite

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.

show abstract

Section: Introductioncontrasting

confidence: 49%

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

Steinbusch¹,

Tyagi²,

Schaafsma³

et al. 2014

Opt. Express

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

View full text Add to dashboard Cite

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.

show abstract

“…Another avenue to achieving a THz SLM has been inspired by the work initially developed at millimeter wavelengths where optically excited electron plasmas in photo-active semiconductors serve as a spatial mask in creating Fresnel lenses and reflect-arrays for beam-steering and communication based applications [20,21]. Early studies indicate that THz spatial modulation is also possible with sufficient optical power [22][23][24]. Both electronic and optically controlled SLMs pose as a fast and efficient means to dynamically control electromagnetic radiation thus allowing for realistic methods to perform THz imaging.…”

Section: Introductionmentioning

confidence: 98%

Terahertz single pixel imaging with an optically controlled dynamic spatial light modulator

Shrekenhamer¹,

Watts²,

Padilla³

2013

Opt. Express

201

112

View full text Add to dashboard Cite

We present a single pixel terahertz (THz) imaging technique using optical photoexcitation of semiconductors to dynamically and spatially control the electromagnetic properties of a semiconductor mask to collectively form a THz spatial light modulator (SLM). By co-propagating a THz and collimated optical laser beam through a high-resistivity silicon wafer, we are able to modify the THz transmission in real-time. By further encoding a spatial pattern on the optical beam with a digital micro-mirror device (DMD), we may write masks for THz radiation. We use masks of varying complexities ranging from 63 to 1023 pixels and are able to acquire images at speeds up to 1/2 Hz. Our results demonstrate the viability of obtaining real-time and high-fidelity THz images using an optically controlled SLM with a single pixel detector.

show abstract

Photo-designed terahertz devices

Cited by 55 publications

References 29 publications

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

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

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

Terahertz single pixel imaging with an optically controlled dynamic spatial light modulator

Contact Info

Product

Resources

About