| 1. |
- Meng, Fanqi, et al.
(författare)
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Relativistic Doppler Frequency Up-conversion and Probing the Initial Relaxation of a Non-Equilibrium Electron-Hole Plasma in Silicon
- 2015
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Ingår i: 2015 40TH INTERNATIONAL CONFERENCE ON INFRARED, MILLIMETER AND TERAHERTZ WAVES (IRMMW-THZ). - : IEEE. - 9781479982721 - 9781479982714
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Konferensbidrag (refereegranskat)abstract
- we demonstrate experimentally the relativistic Doppler frequency up-conversion of the THz pulses from the counter-propagating ionized plasma front in silicon. The observed frequency up-conversion can be well modeled by the 1D FDTD simulations if significant short scattering time (well below 10 fs) in the plasma is assumed. To further elucidate the scattering rate in the electro-hole plasma, we performed pump probe experiment employing ultra-broadband (150 THz) THz-Mid-Infrared pulse. The results show the scattering time decreases from similar to 200 fs down to similar to 20 fs when the carrier density increases up to 10(19)-cm(-3), and then saturates for higher densities. Such scattering time dependence on plasma carrier density can be very well fitted by the Drude model for thermalized electron-holes, and the saturation behavior is attributed to electron-hole phase-space restriction as the plasma becomes degenerate. The resultant much shorter scattering time measured with non-thermalized plasma is in good accordance with the Doppler experiment, which demonstrates Doppler geometry an effective method for probing non-equilibrium plasma dynamics.
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| 2. |
- Bulcha, Berhanu, et al.
(författare)
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Phase Locking of a 2.5 THz Quantum Cascade Laser to a Microwave Reference using THz Schottky Mixer
- 2015
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Ingår i: 40th International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz 2015, Hong Kong, China, 23-28 August. - 2162-2027. - 9781479982721
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Konferensbidrag (refereegranskat)abstract
- The frequency of a 2.5 THz QCL are stabilized to sub-hertz accuracy by phase-locking to a stable 100 MHz microwave reference, using a 2.3–3.2 THz room temperature Schottky diode based harmonic mixer. The down-converted phase locked beat note is stable over a long term test.
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| 3. |
- Engdahl, Anders, et al.
(författare)
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Microspectroscopic infrared specular reflection studies of multi-component urinary stones at beamline D7 at the MAX IV laboratory, Lund Sweden
- 2015
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Ingår i: IRMMW-THz 2015 - 40th International Conference on Infrared, Millimeter, and Terahertz Waves. - 9781479982721
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Konferensbidrag (refereegranskat)abstract
- At the beamline D7 at the MAX III ring at the MAX IV laboratory we have a setup for infrared microspectroscopy which is usable from 30 to 10000 cm-1. In this project specular reflection infrared microspectroscopy was used for chemical imaging of cross-sectioned urinary stones. to determine their chemical composition and morphology simultaneously. Absorption spectral bands were recovered from reflection spectra by Kramers-Kronig transform. Use of far-infrared radiation provides high-contrast images and allows more precise constituent distribution determinations than mid-infrared because band asymmetry after the transform caused by diffuse reflection is less in the far-infrared.
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| 4. |
- Gandini, E., et al.
(författare)
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On the development of a quasi-optical system for short and long range standoff imagers
- 2015
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Ingår i: 40th International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz 2015, Hong Kong, China, 23-28 August. - 2162-2027. - 9781479982721
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Konferensbidrag (refereegranskat)abstract
- The European Defense Agency project TIPPSI aims to produce a phenomenology study to evaluate the performance of standoff imagers for security applications at submillimeter frequencies. In this context, a modular optical architecture is being developed. It is composed by a compact Dragonian system to image at short ranges coupled to a confocal system that operates at a larger focusing distance. The performance of the two solutions is described in this contribution.
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| 5. |
- Ponseca, Carlito S., et al.
(författare)
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Understanding charge carrier dynamics in solar cell materials using time resolved terahertz spectroscopy
- 2015
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Ingår i: IRMMW-THz 2015 - 40th International Conference on Infrared, Millimeter, and Terahertz Waves. - 9781479982721
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Konferensbidrag (refereegranskat)abstract
- The need for developing highly efficient solar cell devices have never been so pressing until recently when the urgency of using renewable energy sources becomes more evident. There are several promising technologies being explored by many groups with the sole purpose of optimizing harvesting sunlight and converting it to useful electricity. These include, but not limited to, dye- and quantum dot-sensitized, bulk heterojunction organic, inorganic nanowires, and very recently perovskite-based solar cells. In this talk, charge carrier dynamics of an assortment of solar cell technologies probed using time-resolved terahertz spectroscopy will be presented. Electron injection, mobility, charge carrier lifetime and recombination dynamics will be discussed.
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