Photo-Dember terahertz emitter excited with an Er:fiber laser

Klatt, Gregor; Surrer, B.; Stephan, D.; Schubert, Olaf; Fischer, M.; Faist, Jérôme; Leitenstorfer, Alfred; Huber, Rupert; Dekorsy, Thomas

doi:10.1063/1.3543627

Cited by 38 publications

(29 citation statements)

References 21 publications

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“…This bandwidth is about a factor of two larger than obtained with photo-Dember emitters at 1550 nm. 5 A THz peak field strength of 0.7 V/cm has been measured when the emitter is operated at room temperature.…”

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confidence: 99%

“…Electrical heating by the required DC bias and optical heating due to absorption further worsens the situation, leading to thermal runaway and finally destruction of the device. A way around this issue may be unbiased photo-Dember emitters, 5 where no external biasing is required: Concentration gradients of photo-excited carriers and different mobilities of electrons and holes lead to THz emission. However, the THz signal cannot be electrically modulated for lock-in detection as in the case of photoconductors, impeding chopping at high speeds.…”

mentioning

confidence: 99%

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1550 nm ErAs:In(Al)GaAs large area photoconductive emitters

Preu

Mittendorff

Lü

et al. 2012

Applied Physics Letters

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Influence of p-doping on the temperature dependence of InAs/GaAs quantum dot excited state radiative lifetime Appl. Phys. Lett. 101, 183108 (2012) Electrical excitation and detection of magnetic dynamics with impedance matching Appl. Phys. Lett. 101, 182402 (2012) Atomic-resolution study of polarity reversal in GaSb grown on Si by scanning transmission electron microscopy J. Appl. Phys. 112, 093101 (2012) Dielectric strength, optical absorption, and deep ultraviolet detectors of hexagonal boron nitride epilayers

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confidence: 99%

mentioning

confidence: 99%

1550 nm ErAs:In(Al)GaAs large area photoconductive emitters

Preu

Mittendorff

Lü

et al. 2012

Applied Physics Letters

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“…Fig. 10) [115][116][117]. Strong THz wavelets are emitted at the sharp edge of each metallization stripe.…”

Section: Scalable Emitters Based On Lateral Photo-dember Currentsmentioning

confidence: 97%

Scalable Microstructured Photoconductive Terahertz Emitters

Winnerl

2011

J Infrared Milli Terahz Waves

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The development of scalable emitters for pulsed broadband terahertz (THz) radiation is reviewed. Their large active area in the 1 -100 mm 2 range allows for using the full power of state-of-the-art femtosecond lasers for excitation of charge carriers. Large fields for acceleration of the photogenerated carriers are achieved at moderate voltages by interdigitated electrodes. This results in efficient emission of single-cycle THz waves. THz field amplitudes in the range of 300 V/cm and 17 kV/cm are reached for excitation with 10 nJ pulses from Ti:sapphire oscillators and for excitation with 5 μJ pulses from amplified lasers, respectively. The corresponding efficiencies for conversion of near-infrared to THz radiation are 2.5×10 -4 (oscillator excitation) and 2×10 -3 (amplifier excitation). In this article the principle of operation of scalable emitters is explained and different technical realizations are described. We demonstrate that the scalable concept provides freedom for designing optimized antenna patterns for different polarization modes. In particular emitters for linearly, radially and azimuthally polarized radiation are discussed. The success story of photoconductive THz emitters is closely linked to the development of mode-locked Ti: sapphire lasers. GaAs is an ideal photoconductive material for THz emitters excited with Ti: sapphire lasers, which are widely used in research laboratories. For many applications, especially in industrial environments, however, fiber-based lasers are strongly preferred due to their lower cost, compactness and extremely stable operation. Designing photoconductive emitters on InGaAs materials, which have a low enough energy gap for excitation with fiber lasers, is challenging due to the electrical properties of the materials. We discuss why the challenges are even larger for microstructured THz emitters as compared to conventional photoconductive antennas and present first results of emitters suitable for excitation with ytterbium-based fiber lasers. Furthermore an alternative concept, namely the lateral photo-Dember emitter, is presented. Due to the strong THz output scalable emitters are well suited for THz systems with fast data acquisition. Here the application of scalable emitters in THz spectrometers without mechanical delay stages, providing THz spectra with 1 GHz spectral resolution and a signal-to-noise ratio of 37 dB within 1 s, is

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“…By focussing an ultrafast laser, with above band-gap energy, on the metal-semiconductor boundary a spatially asymmetrical distribution of carriers forms near the metal-semiconductor interface [9,10]. Such a device gives intense THz emission as observed by [10][11][12][13][14]. The terahertz emission has been attributed to an asymmetrical diffusion current due to the initial asymmetrical carrier distribution.…”

Section: Introductionmentioning

confidence: 99%

Fluence and polarisation dependence of GaAs based Lateral Photo-Dember terahertz emitters

McBryde¹,

Barnes²,

Berry³

et al. 2014

Opt. Express

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We characterise THz output of lateral photo-Dember (LPD) emitters based on semi-insulating (SI), unannealed and annealed low temperature grown (LTG) GaAs. Saturation of THz pulse power with optical fluence is observed, with unannealed LTG GaAs showing highest saturation fluence at 1.1 ± 0.1 mJ cm −2 . SI-GaAs LPD emitters show a flip in signal polarity with optical fluence that is attributed to THz emission from the metal-semiconductor contact. Variation in optical polarisation affects THz pulse power that is attributed to a local optical excitation near the metal contact.

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Photo-Dember terahertz emitter excited with an Er:fiber laser

Abstract: Crossover between surface field and photo-Dember effect induced terahertz emission

Cited by 38 publications

References 21 publications

1550 nm ErAs:In(Al)GaAs large area photoconductive emitters

1550 nm ErAs:In(Al)GaAs large area photoconductive emitters

Scalable Microstructured Photoconductive Terahertz Emitters

Fluence and polarisation dependence of GaAs based Lateral Photo-Dember terahertz emitters

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