H. Ohtake

Application of high average-power THz radiation to measure far infrared absorption spectrum of supercritical fluid

A high average-power THz radiation enables us to acquire far infrared absorption spectra of supercritical fluids with a high signal to noise ratio in short time. Local structure of the fluid is investigated through the spectra.

Saturation of intense THz-radiation power from femtosecond-laser irradiated InAs in a high magnetic field

Summary form only given. We have investigated the intense THz radiation from InAs by applying a strong magnetic field up to 5T. The sample was non-doped bulk InAs with a [100] surface. A mode-locked Ti:sapphire laser was used for an excitation source. A liquid-helium-cooled Si bolometer was provided for detection. We show magnetic field dependence of the THz-radiation intensity. To obtain more detailed information, we took spectra by a polarizing Michelson interferometer. We show the center frequency at each magnetic field.

LiCAF crystal as a new vacuum ultraviolet optical material with transmission down to 112 nm

We report the superior transmission characteristics of LiCaAlF/sub 6/ (LiCAF) down to 112 nm. From the transparent wavelength shorter than that of conventional LiF, the non-hydroscopic nature of LiCAF, and the better mechanical properties compared with LiF, LiCAF is shown to be an ideal optical material for the vacuum ultraviolet region.

Anomalous power and spectrum dependence of THz radiation from femtosecond-laser-irradiated InAs in a high magnetic field of 14 T

We report on the THz radiation from femtosecond-laser-irradiated InAs in a high magnetic field up to 14 T. It is found that the radiation power exhibits anomalous magnetic-field dependence, including saturation, decrease, and recovery up to 14 T.

Simultaneous measurement of thickness and water content of thin black ink films for printing using THz-radiation

A simple, non-contact and simultaneous measurement for thickness and water content of black ink films is performed using THz-radiation from its frequency-dependent and independent absorption characteristics of black ink films.

Generation of 0.336-J, 10-Hz, 266-nm pulses from Nd:YAG laser using large Li/sub 2/B/sub 4/O/sub 7/ nonlinear crystals

Summary form only given. We have confirmed the long-term stability of the fourth harmonic generation of a Nd:YAG laser by use of Li/sub 2/B/sub 4/O/sub 7/ crystals with a cascade scheme. We report 336-mJ, 266-nm pulse generation from a 10-Hz, Q-switched Nd:YAG laser with a total conversion efficiency of 23%, and the long-term stability of over 5 hour. This performance is sufficiently good for the pump source of the TW-class UV femtosecond laser system. Additionally this high pulse energy UV laser is attractive for the substitution of the most of industrial KrF excimer lasers used for annealing applications.

Large-aperture Ce/sup 3+/:LiCaAlF/sub 6/ power-amplifier module for the terawatt-class ultraviolet solid-state laser system

Coaxially- pumped large-aperture Ce:LiCaAlF/sub 6/ power-amplifier module for the TW ultraviolet CPA laser system is demonstrated to have 98-mJ output with 25% extraction efficiency. This performance of the gain module is sufficiently good for the TW-class UV CPA laser system. Such solid-stale laser development will open up a new category of UV high-peak-power laser systems for the real world applications.

Generation of THz-radiation from resonant absorption in strained multiple-quantum-well in a magnetic field

Wavelength dependent THz-radiation from strained multiple-quantum-well by a 1-T magnetic field had shown the clear resonance behavior near the photoluminescence peak. Comparisons with bulk semi-insulating GaAs will also be presented.

Evaluation of laser media using a compact, low-jitter, 3-MeV picosecond electron-beam source with a photocathode

The properties of an electron-beam-pumped Ce/sup 3+/:LiCaAlF/sub 6/ (Ce:LiCAF): ultraviolet laser medium are shown to significantly differ from those of an optically pumped medium using a table-top-sized, low-jitter, 3-MeV picosecond electron-beam source with a photocathode.

Application of THz radiation to far-infrared absorption measurements of biopolymers

Terahertz radiation was applied to measurements of far infrared absorption spectra of polypeptides of glycine and L-alanine and cytochrome c in the native and denatured states to investigate collective modes in biopolymers.