Terahertz emission from GaAs and InAs in a magnetic field

Heyman, James; Neocleous, Pelagia; Hebert, Damon; Crowell, P. A.; Müller, Thomas; Unterrainer, K.

doi:10.1103/physrevb.64.085202

Cited by 126 publications

(86 citation statements)

References 16 publications

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“…Using this assumption, we deduce an average THz power of 40 µW. To our knowledge, this value, supported by the large value of P/P probe , represents the strongest THz signal reported in the literature using a Ti:sapphire oscillator as a pump source (Cai et al 1997, Wu and Zhang 1997, McLaughlin et al 2000, Heyman et al 2001, Andrews et al 2002.…”

Section: Resultssupporting

confidence: 49%

A terahertz system using semi-large emitters: noise and performance characteristics

et al. 2002

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We have built a relatively simple, highly efficient, terahertz (THz) emission and detection system centred around a 15 fs Ti:sapphire laser. In the system, 200 mW of laser power is focused on a 120 µm diameter spot between two silverpaint electrodes on the surface of a semi-insulating GaAs crystal, kept at a temperature near 300 K, biased with a 50 kHz, ±400 V square wave. Using rapid delay scanning and lock-in detection at 50 kHz, we obtain probe laser quantum-noise limited signals using a standard electro-optic detection scheme with a 1 mm thick (110) oriented ZnTe crystal. The maximum THz-induced differential signal that we observe is P/P = 7 × 10 −3 , corresponding to a THz peak amplitude of 95 V cm −1 . The THz average power was measured to be about 40 µW, to our knowledge the highest power reported so far generated with Ti:sapphire oscillators as a pump source. The system uses off-the-shelf electronics and requires no microfabrication techniques.

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Section: Resultssupporting

confidence: 49%

A terahertz system using semi-large emitters: noise and performance characteristics

et al. 2002

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“…However, a large number of reports on studies with pulse excitation of semiconductor structures, mostly single or few THz cycles, exists. In most of these investigations, the goal was not the efficient generation of THz radiation, but rather the study of the dynamics of photogenerated carriers in surface depletion layers, 48,49 in semiconductor superlattices, 126 or large electric fields in p-i-n diodes. 120 Therefore, no attempts were made to calibrate the observed signals.…”

Section: -29mentioning

confidence: 99%

“…This induces a surface-parallel component of near-surface carrier transport due to the Lorentz force. [48][49][50] A simpler way to generate strong in-plane components of the carrier acceleration and, hence, strong in-plane components of the THz fields, is with the application of a DC bias to large area coplanar metallic contacts. This creates a strong in-plane electric field.…”

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confidence: 99%

Tunable, continuous-wave Terahertz photomixer sources and applications

Preu

Döhler

Malzer

et al. 2011

Journal of Applied Physics

432

293

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Realization of gigahertz-frequency impedance matching circuits for nano-scale devices Appl. Phys. Lett. 101, 053108 (2012) Synchronization of a renewable energy inverter with the grid J. Renewable Sustainable Energy 4, 043103 (2012) Monolithic high-temperature superconducting heterodyne Josephson frequency down-converter Appl. Phys. Lett. 100, 262604 (2012) Generation of pure phase and amplitude-modulated signals at microwave frequencies Rev. Sci. Instrum. 83, 064705 (2012) Additional information on J. Appl. Phys. This review is focused on the latest developments in continuous-wave (CW) photomixing for Terahertz (THz) generation. The first part of the paper explains the limiting factors for operation at high frequencies $ 1 THz, namely transit time or lifetime roll-off, antenna (R)-device (C) RC rolloff, current screening and blocking, and heat dissipation. We will present various realizations of both photoconductive and p-i-n diode-based photomixers to overcome these limitations, including perspectives on novel materials for high-power photomixers operating at telecom wavelengths (1550 nm). In addition to the classical approach of feeding current originating from a small semiconductor photomixer device to an antenna (antenna-based emitter, AE), an antennaless approach in which the active area itself radiates (large area emitter, LAE) is discussed in detail. Although we focus on CW photomixing, we briefly discuss recent results for LAEs under pulsed conditions. Record power levels of 1.5 mW average power and conversion efficiencies as high as 2 Â 10 À3 have been reached, about 2 orders of magnitude higher than those obtained with CW antenna-based emitters. The second part of the paper is devoted to applications for CW photomixers. We begin with a discussion of the development of novel THz optics. Special attention is paid to experiments exploiting the long coherence length of CW photomixers for coherent emission and detection of THz arrays. The long coherence length comes with an unprecedented narrow linewidth. This is of particular interest for spectroscopic applications, the field in which THz research has perhaps the highest impact. We point out that CW spectroscopy systems may potentially be more compact, cheaper, and more accurate than conventional pulsed systems. These features are attributed to telecom-wavelength compatibility, to excellent frequency resolution, and to their huge spectral density. The paper concludes with prototype experiments of THz wireless LAN applications. For future telecommunication systems, the limited bandwidth of photodiodes is inadequate for further upshifting carrier frequencies. This, however, will soon be required for increased data throughput. The implementation of telecom-wavelength compatible photomixing diodes for down-conversion of an optical carrier signal to a (sub-)THz RF signal will be required.

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“…In this paper we concentrate on the compound semiconductor GaAs. Emission from GaAs in the absence of an applied electric field has been studied as a function of magnetic field 3,4 and as a function of excitation optical fluence. 4 With an applied electric field, GaAs becomes an effective photoconductive (PC) emitter.…”

Section: Introductionmentioning

confidence: 99%

Semiconductor terahertz emitters

Hargreaves

Lewis

Henini

2007

Microelectronics: Design, Technology, and Packaging III

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There is a demand for more efficient sources of electromagnetic radiation in the terahertz (THz, 10 12 Hz) frequency region. One common method of generating THz-frequency radiation is to direct fs pulses of nearinfrared laser radiation onto a material which then re-radiates. This approach permits coherent pulses of THz radiation to be produced which, for example, may be used for time-domain spectroscopy (TDS). There are three principal mechanisms by which THz radiation is generated under the stimulus of ultra-short pulses: optical rectification (OR) in electro-optic materials, photoconductivity (PC) from materials with suitable electrodes, and surface-field (SF) effects in other cases. The III-V compound semiconductor GaAs doped with the acceptor impurity Be produces relatively small amounts of THz radiation via the OR and SF mechanisms, but relatively large amounts via the PC mechanism. We have studied the PC emission of THz radiation from layers of GaAs(Be) grown epitaxially on GaAs substrates. The THz power generated depends on the bias applied to the electrodes approximately quadratically. This is typical of the PC mechanism. The dependence of the THz power on the power of the pump beam is approximately linear. In general, the THz generated tends to decrease as the doping level increases. If the doping level exceeds the Mott limit and the material becomes highly conductive then the photoconductivity and consequently the THz production are quenched.

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Terahertz emission from GaAs and InAs in a magnetic field

Cited by 126 publications

References 16 publications

A terahertz system using semi-large emitters: noise and performance characteristics

A terahertz system using semi-large emitters: noise and performance characteristics

Tunable, continuous-wave Terahertz photomixer sources and applications

Semiconductor terahertz emitters

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