Green pulse regenerative amplification using a Pr:LiYF crystal pumped by GaN blue laser diodes.

Direct regenerative amplifications of green pulses (522 nm) were investigated using a Pr-doped LiYF crystal pumped by GaN blue laser diodes. Green pulses with two different temporal duration regimes, i.e.

First fluoride ceramics lasing at 605 nm at ambient temperature fabricated from chemically synthesized powders.

Laser ceramics have emerged as promising candidates of solid-state laser gain media. However, most laser ceramics are currently focused on lasing in the infrared wavelength range. The very limited options of host materials and the increased optical scattering losses at shorter wavelengths within ceramics have greatly limited the development of visible laser ceramics.

Measurement of a photoinduced transition from a nonordered phase to a transient ordered phase in the organic quantum-paraelectric compound dimethyltetrathiafulvalene-dibromodichloro-p-benzoquinone using femtosecond laser irradiation.

We report a new photoinduced transition from a nonordered phase to a transient ordered phase with symmetry breaking in an organic charge-transfer compound, dimethyltetrathiafulvalene (DMTTF)-dibromodichloro-p-benzoquinone (2,6QBr(2)Cl(2)), which is a neutral compound located near the neutral-ionic phase boundary and shows quantum paraelectricity at low temperatures. By an irradiation of a femtosecond laser pulse, an ionic domain consisting of ~40 molecules is introduced into the neutral lattice per photon, giving rise to coherent molecular oscillations with fractional charge modulations over ~400 molecules. This response is due to the recovery of ferroelectric nature from the quantum paraelectricity by a photoinjection of an ionic domain with a large dipole moment.

Ultrafast modulation of polarization amplitude by terahertz fields in electronic-type organic ferroelectrics.

Ferroelectrics sometimes show large electro-optical and non-linear optical effects, available for polarization rotation and frequency conversion of light, respectively. If the amplitude of ferroelectric polarization is modulated in the picosecond time domain, terahertz repetition of optical switching via electro-optical and non-linear optical effects would be achieved. Here we show that polarization amplitude can be rapidly modulated by a terahertz electric field in an organic ferroelectric, tetrathiafulvalene-p-chloranil (TTF-CA).

Development of a robust model system of FRET using base surrogates tethering fluorophores for strict control of their position and orientation within DNA duplex.

Although distance dependence of Förster resonance energy transfer (FRET) is well-studied and FRET has been extensively applied as "molecular ruler", only limited examples of orientation-dependent FRET have been reported. To create a robust FRET system that precisely reflects the orientation between donor and acceptor, donor and acceptor fluorophores were introduced into a DNA via a D-threoninol scaffold. Strong stacking interactions among intercalated dyes and natural base-pairs suppress free movement of the dyes, clamping them in the duplex in a fixed orientation.