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Negative refraction and the spectral filtering of terahertz radiation by a photonic crystal prism (2011)
Journal Article
Swift, G., Gallant, A., Kaliteevskaya, N., Kaliteevski, M., Brand, S., Dai, D., Baragwanath, A., Iorsh, I., Abram, R., & Chamberlain, J. (2011). Negative refraction and the spectral filtering of terahertz radiation by a photonic crystal prism. Optics Letters, 36(9), 1641-1643. https://doi.org/10.1364/ol.36.001641

We demonstrate how micromachined photonic crystals can be used to negatively refract terahertz frequency light. The photonic crystals, which are constructed from conventional dielectric materials, manipulate the incident beam via interaction with the... Read More about Negative refraction and the spectral filtering of terahertz radiation by a photonic crystal prism.

Long range energy transfer in conjugated polymer sequential bilayers (2011)
Journal Article
Cury, L., Bourdakos, K., Dai, D., Dias, F., & Monkman, A. (2011). Long range energy transfer in conjugated polymer sequential bilayers. The Journal of Chemical Physics, 134(10), Article 104903. https://doi.org/10.1063/1.3560164

Steady-state and time-resolved photoluminescence have been used to investigate the optical properties of bilayer and blend films made from poly(9,9-dioctyl-fluorene-2,7-diyl) (PFO) and poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH PP... Read More about Long range energy transfer in conjugated polymer sequential bilayers.

Silicon based microfluidic cell for terahertz frequencies (2010)
Journal Article
Baragwanath, A., Swift, G., Dai, D., Gallant, A., & Chamberlain, J. (2010). Silicon based microfluidic cell for terahertz frequencies. Journal of Applied Physics, 108(1), Article 013102. https://doi.org/10.1063/1.3456175

We present a detailed analysis of the design, fabrication and testing of a silicon based, microfluidic cell, for transmission terahertz time-domain spectroscopy. The sensitivity of the device is tested through a range of experiments involving primary... Read More about Silicon based microfluidic cell for terahertz frequencies.

Pulsed terahertz signal reconstruction (2007)
Journal Article
Fletcher, J., Swift, G., Dai, D., Chamberlain, J., & Upadhya, P. (2007). Pulsed terahertz signal reconstruction. Journal of Applied Physics, 102(11), https://doi.org/10.1063/1.2818361

A procedure is outlined which can be used to determine the response of an experimental sample to a single, simple broadband frequency pulse in terahertz frequency time domain spectroscopy (TDS). The advantage that accrues from this approach is that o... Read More about Pulsed terahertz signal reconstruction.

Spiroconjugation-enhanced intramolecular charge-transfer state formation in a polyspirobifluorene homopolymer (2007)
Journal Article
King, S., Hintschich, S., Dai, D., Rothe, C., & Monkman, A. (2007). Spiroconjugation-enhanced intramolecular charge-transfer state formation in a polyspirobifluorene homopolymer. Journal of Physical Chemistry C, 111(50), 18759-18764. https://doi.org/10.1021/jp0755138

In this work we demonstrate the complex excited-state behavior of polyspirobifluorene in the solid state, which, due to the interaction of the spiroconjugated side group, readily forms a charge-transfer (CT) excited state of lower energy than the sin... Read More about Spiroconjugation-enhanced intramolecular charge-transfer state formation in a polyspirobifluorene homopolymer.

Exciton annihilation in a polyfluorene: Low threshold for singlet-singlet annihilation and the absence of singlet-triplet annihilation (2007)
Journal Article
King, S., Dai, D., Rothe, C., & Monkman, A. (2007). Exciton annihilation in a polyfluorene: Low threshold for singlet-singlet annihilation and the absence of singlet-triplet annihilation. Physical review B, 76(8), https://doi.org/10.1103/physrevb.76.085204

Ultrafast photoinduced absorption measurements have been used to directly investigate singlet-singlet annihilation in polyfluorene. The pump fluence threshold for annihilation to dominate the decay was measured to be ∼1 μJ cm−2 corresponding to an ex... Read More about Exciton annihilation in a polyfluorene: Low threshold for singlet-singlet annihilation and the absence of singlet-triplet annihilation.

Propagation of terahertz radiation through random structures: an alternative theoretical approach and experimental validation (2007)
Journal Article
Fletcher, J., Swift, G., Dai, D. C., Levitt, J., & Chamberlain, J. (2007). Propagation of terahertz radiation through random structures: an alternative theoretical approach and experimental validation. Journal of Applied Physics, 101(1), Article 013102. https://doi.org/10.1063/1.2403860

A model describing the propagation of terahertz frequency radiation through inhomogeneous materials is proposed. In such materials (e.g., powders or clothing), the size of the scattering centers, their separation, and the wavelength of the radiation... Read More about Propagation of terahertz radiation through random structures: an alternative theoretical approach and experimental validation.

Two-photon photoluminescence and excitation spectra of InGaN/GaN quantum wells (2006)
Journal Article
Li, Q., Xu, S., Li, G., Dai, D., & Che, C. (2006). Two-photon photoluminescence and excitation spectra of InGaN/GaN quantum wells. Applied Physics Letters, 89(1), https://doi.org/10.1063/1.2218772

We report an observation of efficient two-photon photoluminescence (TPL) of InGaN/GaN multi-quantum-well (MQW) structures using broadband femtosecond near-infrared excitation laser. Near quadratic excitation-intensity dependence and asymmetric collin... Read More about Two-photon photoluminescence and excitation spectra of InGaN/GaN quantum wells.

Observation of both second harmonic and multiphoton absorption induced luminescence in ZnO (2006)
Journal Article
Dai, D., Xu, S., Shi, S., Xie, M., & Che, C. (2006). Observation of both second harmonic and multiphoton absorption induced luminescence in ZnO. IEEE Photonics Technology Letters, 18(14), 1533-1535. https://doi.org/10.1109/lpt.2006.877620

The confusion over second-harmonic generation (SHG) and multiphoton-absorption (MPA)-induced luminescence in ZnO is observed under excitation with femtosecond laser between 800 and 1000 nm at room temperature. Excitation power dependence measurements... Read More about Observation of both second harmonic and multiphoton absorption induced luminescence in ZnO.

TeraHertz scattering : comparison of a novel theoretical approach with experiment (2006)
Presentation / Conference Contribution
Swift, G., Dai, D., Fletcher, J., Gallant, A., Levitt, J., Abram, R., Beggs, D., Kaliteevski, M., Chamberlain, J., Hwu, R., & Linden, K. (2006, January). TeraHertz scattering : comparison of a novel theoretical approach with experiment. Presented at Terahertz and Gigahertz Electronics and Photonics V, San Jose, CA

At the present time the interaction of Terahertz (THz) radiation with random structures is not well understood. Scattering effects are particularly relevant in this spectral regime, where the wavelength, and the size and separation of scattering cent... Read More about TeraHertz scattering : comparison of a novel theoretical approach with experiment.

Detection of Separation of Laminated Materials by Reflected THz Pulses (2006)
Presentation / Conference Contribution
Fletcher, J., Swift, G., Gallant, A., Levitt, J., Dai, D., & Chamberlain, J. (2006, December). Detection of Separation of Laminated Materials by Reflected THz Pulses. Presented at 9th European NDT Conference (ECNDT)., Berlin

A method is described for the detection and measurement of subwavelength gaps in laminated non-metallic materials, using numerical processing of returned THz echo pulses. Data from artificially constructed phantoms are presented. Deconvolution using... Read More about Detection of Separation of Laminated Materials by Reflected THz Pulses.

Efficient multiphoton-absorption-induced luminescence in single-crystalline ZnO at room temperature (2005)
Journal Article
Dai, D., Xu, S., Shi, S., Xie, M., & Che, C. (2005). Efficient multiphoton-absorption-induced luminescence in single-crystalline ZnO at room temperature. Optics Letters, 30(24), 3377-3379. https://doi.org/10.1364/ol.30.003377

At room temperature, multiphoton absorption- (MPA-) induced photoluminescence in ZnO strongly driven by a femtosecond (fs) near-infrared laser is studied. Two-photon absorption and three-photon absorption are proved to be responsible for the intense... Read More about Efficient multiphoton-absorption-induced luminescence in single-crystalline ZnO at room temperature.

Scattering in THz imaging (2005)
Presentation / Conference Contribution
Fletcher, J., Swift, G., Dai, D., Beggs, D., Abram, R., Kaliteevski, M., Levitt, J., Gallant, A., & Chamberlain*, J. (2005, November). Scattering in THz imaging. Presented at Technologies for Optical Countermeasures II; Femtosecond Phenomena II; and Passive Millimetre-Wave and Terahertz Imaging II., Bruges, Belgium

A new mathematical method, the Phase Distribution Model, is devised for the calculation of attenuation and scattering of THz radiation in random materials. The accuracy of the approximation is tested by comparison with exact calculations and with exp... Read More about Scattering in THz imaging.

Laser induced spectral broadening and hole burning in rare earth doped crystals and coherent optical spectroscopy for frequency upconversion (2004)
Journal Article
Zhou, J., Wang, G., Dai, D., Luo, L., Wong, K., & Yan, Y. (2004). Laser induced spectral broadening and hole burning in rare earth doped crystals and coherent optical spectroscopy for frequency upconversion. Applied Physics B: Lasers and Optics, 78(6), 753-757. https://doi.org/10.1007/s00340-004-1474-x

The excitation spectra for linear fluorescence and for frequency upconversion are recorded in Er3+ doped crystal Er:YAG. An excitation induced spectral broadening and hole-burning are shown to appear at the resonant frequency of the linear fluorescen... Read More about Laser induced spectral broadening and hole burning in rare earth doped crystals and coherent optical spectroscopy for frequency upconversion.

Measurement of femto-second resonant nonlinear refraction in Nd:YVO4 by degenerate pump-probe spectroscopy (2001)
Journal Article
Luo, L., Chen, L., Qiu, Z., Yu, X., Dai, D., Zhou, J., & Kuhl, J. (2001). Measurement of femto-second resonant nonlinear refraction in Nd:YVO4 by degenerate pump-probe spectroscopy. Journal of Applied Physics, 89(12), 8342-8344. https://doi.org/10.1063/1.1374456

The resonant nonlinear refraction in rare-earth-doped solids is studied with femtosecond degenerate pump-probe two-beam coupling spectroscopy. The phase modulation induced by the pump pulses is shown to result in a significant contribution to the dif... Read More about Measurement of femto-second resonant nonlinear refraction in Nd:YVO4 by degenerate pump-probe spectroscopy.

Theory and experiment of coherent wave packet dynamics in rare earth solids: Absorption spectrum vs femtosecond fringe-resolved interferogram (2001)
Journal Article
Luo, Q., Dai, D., Wang, G., Ninulescu, V., Yu, X., Luo, L., …Yan, Y. (2001). Theory and experiment of coherent wave packet dynamics in rare earth solids: Absorption spectrum vs femtosecond fringe-resolved interferogram. The Journal of Chemical Physics, 114(4), 1870-1875. https://doi.org/10.1063/1.1335659

Coherent dynamic property of neodymium yttrium aluminum garnet (Nd:YAG) crystal at 77 K is studied via the conventional absorption, the femtosecond fringe-resolved wave packet interferometry, and the related difference-phase spectrum. The recorded in... Read More about Theory and experiment of coherent wave packet dynamics in rare earth solids: Absorption spectrum vs femtosecond fringe-resolved interferogram.

Rare earth materials for population density control with ultra-high-speed optical pulses, (2000)
Journal Article
Dai, D., Luo, Q., Li, R., Yu, X., Qiu, Z., Zhou, J., & Yang, Y. (2000). Rare earth materials for population density control with ultra-high-speed optical pulses,. IEEE Photonics Technology Letters, 12(8), 1034-1036. https://doi.org/10.1109/68.867999

The rare earth materials, KNdFe(CN)6.3H2O (KNFCN), NdFe(CN)6.4H2O (NFCN), and NdFeO3 (NFO) are characterized by absorption and fluorescence spectra. The dephasing times (T2) and the fluorescent lifetimes (T1) of the materials are determined. The crit... Read More about Rare earth materials for population density control with ultra-high-speed optical pulses,.

Fluorescence-detected ultrafast free-induction decay in powered rare earth solids (2000)
Journal Article
Luo, Q., Dai, D., Yu, X., Qiu, Z., Zhou, J., Yan, C., & Chen, Z. (2000). Fluorescence-detected ultrafast free-induction decay in powered rare earth solids. Chinese Physics Letters, 17(2), 101-103. https://doi.org/10.1088/0256-307x/17/2/009

Fluorescence interferometry is developed and applied to study ultrafast amplitude and phase dynamics for free-induction decay in powdered rare earth solids. The time-resolved phase dynamics of free-induction decay through-out the decaying process is... Read More about Fluorescence-detected ultrafast free-induction decay in powered rare earth solids.

Coherent population density control by ultra-high repetition rate femtosecond optical pulse pairs for optical switching (1999)
Journal Article
Yu, X., Dai, D., Cai, Z., Luo, Q., Ninulescu, V., & Zhou, J. (1999). Coherent population density control by ultra-high repetition rate femtosecond optical pulse pairs for optical switching. Optics Communications, 164(4-6), 177-184. https://doi.org/10.1016/s0030-4018%2899%2900198-4

A semi-classical theory of coherent population density control (CPDC) by ultra-high repetition rate (100 GHz) femtosecond (fs) optical pulse pairs was developed. The CPDC involving the use of fs pulse pairs to induce fast switching ‘on' and ‘off' for... Read More about Coherent population density control by ultra-high repetition rate femtosecond optical pulse pairs for optical switching.