Marilou Cadatal

Development of Vacuum Ultraviolet Streak Camera System for the Evaluation of Vacuum Ultraviolet Emitting Materials

Details of the design and development of a bright vacuum ultraviolet Seya–Namioka type spectrometer and streak camera system with reflection-type input optics is presented. The Seya–Namioka spectrometer has a 40 mm by 45 mm holographic grating with a groove density of 600 grooves/mm, linear dispersion of 8 nm/mm, and effective F-number of 4.2. To eliminate loss of light by absorption, the streak camera imaging unit uses Al and MgF2 coated imaging optics with at least 80% reflection from 125–850 nm and has an effective F-number of 4. It is equipped with a synchronized scan unit that can be tuned to 82 MHz and a slow scan speed unit that can measure up to 2-MHz single event. Temporal response of the system at the 20-ns scanning range is evaluated to be around 260 ps.

Vacuum ultraviolet optical properties of a micro-pulling-down-method grown Nd 3+ :(La 0.9 ,Ba 0.1 )F 2.9

Nd3+:(La1−x,Bax)F3−x(x=0.1) is efficiently grown by the micro-pulling-down method. Characterization of its optical properties reveals that it is transparent in the vacuum ultraviolet region with an absorption edge at around 180 nm. It has fluorescence centered at 175 nm with a bandwidth of 12 nm and a lifetime of 6.1 ns as measured by a vacuum ultraviolet streak camera and spectrometer combination. It is proposed to be suitable as a vacuum ultraviolet scintillator and a potential laser material.

Nd3+:(La1-xBax)F3-x Grown by Micro-Pulling Down Method as Vacuum Ultraviolet Scintillator and Potential Laser Material

Nd3+:(La1-xBax)F3-x (x = 0.1) efficiently grown by the micro-pulling down method is explored. Transparency down to 164 nm and broad fluorescence centered at 175 nm make it a novel vacuum ultraviolet scintillator and a potential tunable laser material with the capability of short pulse amplification.

Laser Quality Ce3+:LiCaAlF6 Grown by Micro-Pulling-Down Method

We describe the successful growth of a laser quality Ce3+:LiCaAlF6 crystal using the micro-pulling down method. The crystal is grown using less than one gram of raw material and a pulling rate of 0.1 mm/min. Ultraviolet laser emission at 290 nm with 23% slope efficiency and 1 mJ pulse energy is demonstrated from a Brewster-cut crystal, which is 30 mm in length and 2 mm in diameter. The flexibility and lower cost of this growth technique will markedly reduce the cost of growing laser grade crystals.

Birefringence of β-BaB2O4 crystal in the terahertz region for parametric device design

β-BaB2O4 (BBO) was found to have huge birefringence in the 0.1–1.1THz frequency region. Polarized terahertz transmission spectroscopy revealed a Δn∕n value of about 0.12±0.02. This result could be related to a polarization-dependent absorption that was observed at about 0.65THz; in close agreement with first principles-calculations, showing this to be due to low-frequency phonon modes of the [B3O6]3-rings. These findings suggest the utilization of the birefringent properties of BBO for optical parametric devices including amplifiers and oscillators, operating in the terahertz regime.

Reduction of Nonlinear Absorption in Li2B4O7 by Temperature- and Repetition Rate-Control

We address the critical issue of thermal dephasing of the UV harmonic generation process due to nonlinear absorption in Li2B4O7 crystals. Reduction of nonlinear absorption is achieved by increasing the crystal temperature up to 200 °C and reducing the pulse repetition rate. Our results show the way for significant improvement of the conversion efficiency for the fourth harmonic generation of Nd lasers using Li2B4O7 crystals.

Terahertz-Radiation Photoconductive Antenna in Sputtered Zinc Oxide Thin Film

We report on terahertz (THz)-radiation generation from a photoconductive antenna fabricated on a zinc oxide (ZnO) thin film. This ZnO thin film was epitaxially grown on a sapphire single crystal by rf-planar magnetron sputtering. The THz-radiation power from the ZnO thin film did not saturate below 14-kV/cm-biased electric field.

Micro-pulling down method grown Ce:LiCAF as ultraviolet laser

We report the first successful micro-pulling down method growth and ultraviolet emission from a Ce:LiCAF crystal. With two-side pumping configuration, 23% slope efficiency is obtained from the 290-nm emission of a 30 mm-long, 2 mm-wide Brewster-cut crystal.

Characterization of Ce:LuLiF 4 as fast scintillator using storage ring free-electron lasers

Ce:LuLiF4 as fast scintillator is evaluated using a storage ring free-electron laser operated in deep ultraviolet region. The response time is found to be varied for the excitation of the different absorption band.

Terahertz birefringence of β-BaB2O4 (BBO) crystal

Birefringence was observed for a beta-BaB2O4 crystal in the 0.1 to 1.1 terahertz region. The calculated Deltan value was ~0.296. Moreover, an angle-dependent absorption band observed at ~0.65 terahertz is attributed to low-frequency phonon modes.