Picosecond Photoconductors: Physical Properties and Applications

Auston, D. H.

doi:10.1016/b978-0-12-440880-7.50008-0

Cited by 79 publications

(9 citation statements)

References 32 publications

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“…In the former case, an external electric field is applied across a gap formed by electrodes, which is excited by the optical pulse (Auston, 1983;Auston et al, 1984;Fattinger and Grischkowsky, 1989). The optical pulse is often arranged at normal incidence and the bias field is parallel to the photoconductor surface.…”

Section: Generation Of Thz Radiation By Photoconductivitymentioning

confidence: 99%

“…Examples include low-temperature grown or ion-implanted GaAs and silicon (McIntosh et al, 1995;Shan and Heinz, 2004;Krotkus and Coutaz, 2005;Mikulics et al, 2006). Following the pioneering work of Auston (1983), Grischkowsky (1993), and their coworkers, researchers optimized ultrafast photoconductive switches in the past two decades to permit generation and field-resolved detection of electromagnetic transients up to $5 THz. Such a bandwidth, while impressive, actually reflects the finite response time of photoconductive materials rather than the ideal bandwidth that could be obtained from current state-of-the-art mode-locked laser pulses.…”

Section: Generation Of Thz Radiation By Photoconductivitymentioning

confidence: 99%

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Carrier dynamics in semiconductors studied with time-resolved terahertz spectroscopy

et al. 2011

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Time-resolved, pulsed terahertz spectroscopy has developed into a powerful tool to study charge carrier dynamics in semiconductors and semiconductor structures over the past decades. Covering the energy range from a few to about 100 meV, terahertz radiation is sensitive to the response of charge quasiparticles, e.g., free carriers, polarons, and excitons. The distinct spectral signatures of these different quasiparticles in the THz range allow their discrimination and characterization using pulsed THz radiation. This frequency region is also well suited for the study of phonon resonances and intraband transitions in low-dimensional systems. Moreover, using a pump-probe scheme, it is possible to monitor the nonequilibrium time evolution of carriers and low-energy excitations with sub-ps time resolution. Being an all-optical technique, terahertz time-domain spectroscopy is contact-free and noninvasive and hence suited to probe the conductivity of, particularly, nanostructured materials that are difficult or impossible to access with other methods. The latest developments in the application of terahertz time-domain spectroscopy to bulk and nanostructured semiconductors are reviewed.

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Section: Generation Of Thz Radiation By Photoconductivitymentioning

confidence: 99%

Section: Generation Of Thz Radiation By Photoconductivitymentioning

confidence: 99%

Carrier dynamics in semiconductors studied with time-resolved terahertz spectroscopy

et al. 2011

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“…Using a femtosecond mode-locked laser in single-shot mode, we generate either a single optical pulse or a pair of optical pulses with adjustable amplitudes and time delay t D , which are then converted to electrical pulses using a LT-GaAs/Au photoconductive switch. 19,20 Our optically generated electrical pulses can be relatively timed with subpicosecond resolution, and since our measurement is independent of the absolute pulse timing, there are no trigger jitter effects. Reflection measurements show that typical room-temperature pulse widths at the device are ϳ30 ps, but due to cryostat bandwidth limitations the typical pulse widths are ϳ58 ps at 77 K. In our devices the small-angle free precession period ϳ 300 ps ͑calculated from thin-film measurements of M S and the nominal shape anisotropy͒ is much larger than the current pulse width but comparable to the interpulse delay 0 Ͻ t D Ͻ 2 ns.…”

mentioning

confidence: 99%

Coherent control of nanomagnet dynamics via ultrafast spin torque pulses

Garzon

Webb

et al. 2008

Phys. Rev. B

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The magnetization orientation of a nanoscale ferromagnet can be manipulated using an electric current via the spin transfer effect. Time domain measurements of nanopillar devices at low temperatures have directly shown that magnetization dynamics and reversal occur coherently over a timescale of nanoseconds. By adjusting the shape of a spin torque waveform over a timescale comparable to the free precession period (100-400 ps), control of the magnetization dynamics in nanopillar devices should be possible. Here we report coherent control of the free layer magnetization in nanopillar devices using a pair of current pulses as narrow as 30 ps with adjustable amplitudes and delay. We show that the switching probability can be tuned over a broad range by timing the current pulses with the underlying free-precession orbits, and that the magnetization evolution remains coherent for more than 1 ns even at room temperature. Furthermore, we can selectively induce transitions along free-precession orbits and thereby manipulate the free magnetic moment motion. We expect this technique will be adopted for further elucidating the dynamics and dissipation processes in nanomagnets, and will provide an alternative for spin torque driven spintronic devices, such as resonantly pumping microwave oscillators, and ultimately, for efficient reversal of memory bits in magnetic random access memory (MRAM).Comment: 4 pages, 3 figures, submitted to Nature Physic

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“…5 We performed DC biasing experiments on switches with different thickness and gap width and found that a 1 mm thick Ga:As chip with a 3 mm gap between ohmic contacts could electrically isolate a direct-current bias as high as 5.7 kV in room light. Visible light (1.7-3.1 eV) can promote charge carriers across the 1 .4 eV band gap of Ga:As.…”

Section: Switch Designmentioning

confidence: 99%

<title>Passive, 100-ps, x-ray-driven pulser for gating microchannel-plate detectors</title>

Fry

Springer

1995

SPIE Proceedings

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A means for electrically gating a microchannel-plate (MCP) detector using a fast rise-time, x-ray-driven Auston switch is presented. The Ga:As Auston switches which are used in the pulser were tested to stand-off 7 kV DC bias, and can therefore be used without ramped biasing electronics. Calculations for the x-ray sensitivity of the Auston switches in the pulser are presented. The pulsers were tested with visible light and x-rays and were shown to exhibit 90 ps rise-time between zero and 1 kV when triggered by a 1 .2 mJ/cm2 flux of sub-kilovolt x-rays as measured by silicon p-i-n diodes. The pulser was designed to trigger MCP detectors which were used to spectrally characterize an x-ray heated target. A major attribute of this pulser is that it can be pre-set to gate a detector with less than a few picoseconds timing jitter with no foreknowledge of the time of arrival of the triggering x-ray flux.

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Picosecond Photoconductors: Physical Properties and Applications

Cited by 79 publications

References 32 publications

Carrier dynamics in semiconductors studied with time-resolved terahertz spectroscopy

Carrier dynamics in semiconductors studied with time-resolved terahertz spectroscopy

Coherent control of nanomagnet dynamics via ultrafast spin torque pulses

<title>Passive, 100-ps, x-ray-driven pulser for gating microchannel-plate detectors</title>

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