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We have developed a record high-repetition-rate terahertz-wave parametric generator using MgO:LiNbO3. The generator is pumped using a post-amplified, sub-nanosecond, and passively Q-switched SESAM microchip laser running with a 100 kHz repetition frequency. A double-pass dual-end-pumped Nd:YVO4 amplifier was developed and the microchip laser output was efficiently amplified between 5 mW-4.4 W. This...
We propose THz-wave real-time imaging system with high resolution based on second harmonic generation in nonlinear organic DAST crystal. The spatial resolution is estimated to be less than ∼3×λTHz.
We report on the generation of high-brightness (high peak power and narrow linewidth) continuously tunable subterahertz waves by optical parametric wavelength conversion using lithium niobate as a nonlinear optical crystal. The high-brightness subterahertz waves were achieved by expanding the interaction volume of the pumping beam and the idler wave, as well as the subterahertz wave, during wavelength...
An ultrathin Terahertz (THz) quarter wave plate with high transmittance by flexible metamaterial is proposed in this paper. The device employs double layers of split ring resonator (SRR) with a polymer as the substrate. Due to the anisotropy of the SRR, it obtains a quarter wave plate with the transmittance of 0.72 and the ellipticity of 0.9994 at 0.854 THz from simulation. The device has a thickness...
A sensitive terahertz (THz)-wave detection based on a nonlinear up-conversion process in MgO:LiNbO3 crystal has been demonstrated by measuring the pulse energy of depleted pump wave. Spectroscopic measurements in the wide frequency range from 1.0 to 2.6 THz were achieved with a single optical detector. This method is independent of the output direction of noncollinear phase-matched up-conversion waves...
Metamaterial device with double layers of split ring resonators (SRRs) on flexible substrate is proposed for building a new terahertz (THz)-wave near-field imaging system with real-time performance. The SRRs work as an array of probes that reserve the object near-field information and transfer it to the detection system, which is based on the frequency up-conversion with nonlinear crystal DAST (4-dimethylamino-N-methyl-4-stilbazolium...
We have demonstrated kW-peak-power terahertz (THz)-wave parametric generation and 70 dB-dynamic-range detection by using efficient surface-coupling configuration. The system is capable of producing and detecting monochromatic THz-wave pulses in the wide frequency range from 0.8 to 2.8 THz.
We demonstrate a tunable mid-infrared (6.3–7.8-µm) vortex laser formed of a 1-µm vortex pumped optical parametric oscillator and a difference frequency generator. Maximum output energy of 160-µJ was obtained at a wavelength of 6.5-µm.
We presented the first demonstration of the helicity control of the optical vortex output from a vortex-pumped optical parametric oscillator by inverting the wavefront helicity of the pump vortex beam.
We demonstrated for the first time an ultra-violet vortex output without a spatial separation of phase singularities by frequency-doubling a green vortex laser with a pair of β-BaB2O4 and reversed β-BaB2O4 crystals.
Optical vortex modes, possessing a spiral wavefront, an annular intensity profile and orbital angular momentum, mℏ (m is termed a topological charge), have been intensely investigated in various applications, such as an optical tweezer, quantum information processing, and laser ablation. Recently, we discovered that the wavefront helicity (clock-wise or counter clock-wise spiral direction) of the...
Fractional vortex lasers with a fractional topological charge, l, exhibiting a unique fractional radial opening, have been attractive for the optical manipulating of microscopic particles and super-resolution spectroscopy based on stimulated emission depletion. They have also recieved much attention in fundamental physics, including an analogy concerning the quantum flux in the Aharonov-Bohm effect...
We demonstrated high energy 2 μm optical vortex pulse production from an optical vortex pumped hemispherical optical parametric oscillator. Maximum 2 μm optical vortex pulse energy of 2.1 mJ was achieved.
Ultrabroadband polarization vortex generation ranging ∼600 to ∼800nm without polarization dispersion was demonstrated using a photonic-crystal radial polarizer. It enables us to investigate closed-loop coherence in the ultrashort temporal and/or ultrabroad spectral region(s).
Electron in a quasi one-dimensional NbSe3 whisker crystal form a collective state at low temperature. It is called charge density wave (CDW) state. This article discusses about the coherence properties of the quasi one-dimensionality globally along the entire closed loop which is probed using the polarization vortex.
The generation method of spatial-dispersion-free optical vortices using polarization singularity due to an axially-symmetric polarizer was proposed and demonstrated with an ultrabroad-band light (∼350 to ∼1000 nm) and an ultrashort optical pulse (∼50 fs).
The generation method of spatial-dispersion-free optical vortices using polarization singularity due to an axially-symmetric polarizer was proposed and demonstrated with an ultrabroad-band light (~350 to ~1000 nm) and an ultrashort optical pulse (~50 fs).
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