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Knab, J.R. (author), Adam, A.J.L. (author), Chakkittakandy, R. (author), Planken, P.C.M. (author)Using near-field, terahertz time-domain spectroscopy (THz-TDS), we investigate how the addition of a dielectric material into a subwavelength-diameter, cylindrical waveguide affects its transmission properties. The THz electric near-field is imaged with deep subwavelength resolution as it emerges from filled and unfilled waveguides....journal article 2010
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Ramakrishnan, G. (author), Chakkittakandy, R. (author), Planken, P.C.M. (author)Generation of subpicosecond terahertz pulses is observed when graphite surfaces are illuminated with femtosecond near-infrared laser pulses. The nonlinear optical generation of THz pulses from graphite is unexpected since, in principle, the material possesses a centre of inversion symmetry. Experiments with highly oriented pyrolytic graphite...journal article 2009
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Chakkittakandy, R. (author), Corver, J.A.W.M. (author), Planken, P.C.M. (author)We describe a simple terahertz (THz) time domain spectrometer with a bandwidth extending up to 7.5 THz. We show that by keeping the generation and detection crystals close to each other a high signal-to-noise ratio (SNR) can be achieved without using lock-in detection and dry nitrogen flushing. The observed spectra show very good agreement with...journal article 2008