The efficiency of multi-watt ultraviolet radiation generation by harmonics processes in β-BaB2O4 (BBO) can be improved by reducing thermal dephasing. The dephasing arises from local heating of BBO by the linear absorption of green (second harmonic) and ultraviolet (fourth harmonic) radiation by crystal defects that are induced by two-photon absorption of high peak power ultraviolet radiation. Such absorption can be reduced by decreasing the repetition rate to ∼1 kHz to allow the defects to decay between the laser pulses and/or heating BBO crystal to 150–200 °C to increase the decay rate of the induced defects.

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We report on the intense terahertz emission from InAs/GaAs quantum dot (QD) structures grown by molecular beam epitaxy. Results reveal that the QD sample emission was as high as 70% of that of a p-type InAs wafer, the most intense semiconductor emitter to date. Excitation wavelength studies showed that the emission was due to absorption in strained undoped GaAs, and corresponds to a two order-of-magnitude enhancement. Moreover, it was found that multilayer QDs emit more strongly compared with a single layer QD sample. At present, we ascribe the intense radiation to huge strain fields at the InAs/GaAs interface.

We report an over one-order-of magnitude improvement in the response time of conventional hydrothermal method-grown zinc oxide (ZnO) scintillator by introducing additional quenching channels via intentional indium ion doping. A 3-ps fluorescence decay time constant is achieved, therefore making it the fastest scintillator operating below 100 nm to date. Using this indium-doped ZnO, relative jitter between extreme ultraviolet free electron laser (EUV-FEL) probe and optical pump pulses is evaluated to be less than 3 ps. Moreover, pulses from these sources can be synchronized with 3-ps accuracy through in-situ observation of relative time difference in single-shot base.

We report the development of filterless deep ultraviolet photoconductive detectors using cerium fluoride (CeF3) thin films fabricated by pulsed laser deposition (PLD). By varying the PLD laser power during thin film growth, we observed that CeF3 breaks down to CeF2 at PLD laser powers greater than 100 mW. This consequently leads to the formation of fluorine defects that effectively narrowed the optical bandgap of the thin films, resulting in the decreased resistivity of the photoconductive detector. Under ultraviolet irradiation, the detector using a thin film grown at 5 mW PLD laser power exhibited close to four orders of magnitude increase in photocurrent compared to the dark current. The spectral response of the photoconductive detectors can be tuned from 300 nm to 400 nm when PLD laser powers ranging from 5 mW to 400 mW are used to fabricate the thin films. The filterless nature of the detectors simplifies their production, and their tunability can extend their use to a wider range of applications.