Prototypes using metal, carbon fiber and composite field emission sources modulated by a laser beam

Mousa, Marwan S.; Brugat, M.; Sheshin, E.P.; Hagmann, Mark J.

doi:10.1016/s0304-3991(01)00121-8

Cited by 13 publications

(5 citation statements)

References 12 publications

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“…These measurements have been made using field emitter tips of tungsten, molybdenum, zirconium carbide, carbon fiber, and other materials 21 . For example, measurements were made using a sealed field emission tube (Leybold AG model 55460), having a tungsten tip 22 T im e , fs D i s t a n c e , n m k , and the DC field emission current I 0 = 8 A.…”

Section: Experimental Data Supporting the Analysis But Showing Diffimentioning

confidence: 99%

Ultrafast optoelectronic devices using laser-assisted field emission

Hagmann¹

2004

Ultrafast Phenomena in Semiconductors and Nanostructure Materials VIII

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Field emission, quantum tunneling from the clean surface of a nanoscale conductor tip in vacuum, is an extremely fast process, where the instantaneous value of the current responds to the intense applied electric field with a delay of less than 2 fs. The cause for this intrinsic delay is shown to be the traversal time for quantum tunneling. Because the tip is much smaller than optical wavelengths, quasistatic conditions require that the potential of the tip must follow the instantaneous electric field in the imposed optical radiation. There is a resonance that is caused by virtual photon processes in which the electrons absorb single quanta from the radiation field while they are tunneling, to be promoted to energies where the wave function is reinforced by reflections at the classical turning points. Numerical solutions of the time-dependent Schrödinger equation show that the transient response to pulsed radiation consists of beating of the radiation with this resonance, and is intensified by the resonance. Experiments show that when a field emission tube is used as a two-terminal device, by placing the load in the external bias circuit, the response to a pulsed laser is delayed by a time constant equal to the product of the load resistance and the electrode capacitance, typically 10-100 s. Thus, other means for coupling are recommended, including propagation as surface waves on an extended tip and radiation from antennas formed on the tip, and these methods have been tested with microwave prototypes. Ultimately miniature multifunction devices could be built to implement this new technology because nanoscale field emission tubes are now available, and field emitter arrays with 10 10 tips/cm 2 are used in flat panel displays.

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Section: Experimental Data Supporting the Analysis But Showing Diffimentioning

confidence: 99%

Ultrafast optoelectronic devices using laser-assisted field emission

Hagmann¹

2004

Ultrafast Phenomena in Semiconductors and Nanostructure Materials VIII

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“…Measurements of the effect of a TTL amplitude-modulated laser diode on the field emission current have also been made using emitter tips of molybdenum, zirconium carbide, carbon fiber, and other materials 33 . In each case an oscilloscope was used to measure the voltage across an external load resistance.…”

Section: Comparison Of Simulations With Experimental Datamentioning

confidence: 99%

Pulsed and widely tunable terahertz sources for security: imaging and spectroscopy

Hagmann¹,

McBride²,

Hagmann³

2004

SPIE Proceedings

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Terahertz imaging and spectroscopy are being studied for inspecting packages and personnel, but advanced THz sources with much greater power are needed to increase the signal-to-noise ratio, and much greater frequency bandwidth to obtain more information about the target. Photomixing in resonant laser-assisted field emission is a new method that shows potential for increasing both the output power and frequency bandwidth by more than an order of magnitude. Tunneling electrons have a resonance with a radiation field, so a highly focused laser diode (670 nm, 30 mW) increases the emitted current enough to be seen with an oscilloscope, in good agreement with simulations. The electron-emitting tip is much smaller than optical wavelengths, so the potential follows each cycle of the incident radiation field. Electron emission responds to the electric field with a delay < 2 fs, and the current-voltage characteristics of field emission are highly nonlinear. Thus, photomixing in laser-assisted field emission can cause CW current oscillations that may be tuned from DC to 500 THz (1/ ). A field emission current density of 10 12 A/m 2 can be generated using a 20 pJ 70 fs pulse from a Ti:sapphire laser, to provide 185 W THz pulses. Microwave prototypes for 1-10 GHz are now being tested.

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“…Laser-stimulated FE based on the resonance of the potential barrier caused by the electric field of a cw laser beam has attracted interest from researchers in the field of nonlinear optics. [6]- [9] Although it has been theoretically predicted that the current enhancement factor (current with laser/current without laser) of the laser-assisted FE current should reach 10 7 ~ 10 9 , [8], [9] reported experimental current enhancement factors are about 1.01 for a tungsten emitter [7] and 2 for CNT bundles [8] . In the context of ultrafast physics, electron-beam emissions stimulated by fs laser pulses are of interest [10]- [14] .…”

Section: Introductionmentioning

confidence: 99%

Electron field emission based on plasmon resonance

2010

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In this research, an electron emission method which combines field emission and plasmon resonance is proposed and examined. Electron field emission properties of a sharp gold tip under continuous-wave laser irradiation at the plasmonresonant wavelength are investigated. Due to the application of plasmon resonance, the electric field in the vicinity of the emitter is strongly enhanced, resulting in the decrease of emission threshold voltage and the increase of emission current. The emission-area is strongly confined under illumination when the optical electric field is parallel to the emitter shank, and the optical modulation of the emission current is demonstrated.

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Prototypes using metal, carbon fiber and composite field emission sources modulated by a laser beam

Cited by 13 publications

References 12 publications

Ultrafast optoelectronic devices using laser-assisted field emission

Ultrafast optoelectronic devices using laser-assisted field emission

Pulsed and widely tunable terahertz sources for security: imaging and spectroscopy

Electron field emission based on plasmon resonance

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