Investigation of Terahertz Generation due to Unidirectional Diffusion of Carriers in Centrosymmetric GaTe Crystals

Terahertz (THz) radiation generated by ultrafast laser pulses focused on each monoclinic semiconductor crystal, i.e., GaTe, exhibits unique features. By systemically measuring the dependence of the THz output on the ultrafast pump pulses, in terms of polarization, azimuth angle, incident angle, pump...

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Bibliographic Details
Published in:IEEE journal of selected topics in quantum electronics 2011-01, Vol.17 (1), p.30-37
Main Authors: Guibao Xu, Guan Sun, Ding, Yujie J, Zotova, I B, Mandal, K C, Mertiri, A, Pabst, G, Roy, R, Fernelius, N C
Format: Article
Language:English
Subjects:
Azimuth
Beams (radiation)
Broadband terahertz (THz) pulses
Carriers
centrosymmetric crystal
Crystals
Diffusion
Diffusion pumps
GaTe
Gates
Laser beams
Laser excitation
Optical pulse generation
Polarization
Pulse measurements
Pump lasers
Pumps
Semiconductor crystals
Semiconductor lasers
Size measurement
unidirectional diffusion of photogenerated carriers
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Summary:Terahertz (THz) radiation generated by ultrafast laser pulses focused on each monoclinic semiconductor crystal, i.e., GaTe, exhibits unique features. By systemically measuring the dependence of the THz output on the ultrafast pump pulses, in terms of polarization, azimuth angle, incident angle, pump beam size, and pump intensity, we have observed the strong evidence of the unidirectional diffusion of photogenerated carriers within the surface layer of each crystal. Regardless of whether each crystal is pumped above or below its bandgap, the mechanism for THz generation is always attributed to diffusion of the photogenerated carriers. By analyzing data and introducing simplified models, it appears to us that the diffusion of the photogenerated carriers takes place along three different directions.
ISSN:1077-260X
1558-4542
DOI:10.1109/JSTQE.2010.2046628