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We investigated multiple coupled optical parametric oscillators, exhibiting behaviors of strong coupling. Conversion efficiency and slope efficiency stay the same as those for conventional and two coupled optical parametric oscillators whereas linewidths are significantly reduced.
Transversely-propagating THz radiation can be up-converted to an optical wave propagating in the waveguide. Complete photon conversion and single-photon detection can be reached.
Polarization-insensitive phase conjugation, achieved based on difference-frequency generation in a second-order nonlinear composite consisting of stacked KTP plates, was exploited to restore blurred images due to phase distortion as a novel scheme.
A phonon peak at 127 cm−1 due to nonlinear mixing of two transverse-optical phonon frequencies through anharmonicity of LiTaO3 is used to explain enhancements of effective second-order nonlinear coefficients by factors of up to 3.7.
We have implemented a THz source based on intracavity difference frequency generation in stacked GaP plates as an output coupler of an optical parametric oscillator. The total THz output peak power approaches 200 W.
The shortest wavelengths, generated by periodically-poled lithium niobate, are in the vicinity of 62.5 μm at the poling period of 7.1 μm. Large enhancements in the output powers from three gratings are demonstrated.
By mixing three optical frequencies generated by an optical parametric oscillator under a novel configuration based in nonlinear crystals, multiple THz frequencies are efficiently generated. They can be used to pursue variety of novel applications.
We demonstrate efficient generation of far-infrared radiation at the center wavelength of 20.8 μm in lithium niobate in the vicinity of one of the polariton resonances.
In the near-IR and mid-IR regions, periodically-poled LiNbO3 (PPLN) has become an extremely efficient nonlinear medium. However, since long-wavelength cutoff for LiNbO3 is 5.5 µm, the longest wavelength ever generated from such a crystal is 6.8 µm [1]. Such a limit is caused by the strong polariton resonances due to the coupling of transverse-optical phonons with electromagnetic waves, see Fig. 1(a)...
Narrowband terahertz pulses are generated by periodically-poled stoichiometric lithium tantalate with average output powers of 100 μW based on backward optical rectification, which is scalable to at least 10 mW.
Terahertz output peak power as high as 2.7 kW is achieved by difference-frequency generation. Conversion efficiency reaching maximum value of 40% is obtained by reversely stacking four GaP plates.
Based on adhesive-free-bonded periodically inverted KTiOPO4 plates, we implemented a singly-resonant optical parametric oscillator, which has superior advantages of compensating walk-off and oscillating dual-signal wavelengths based on QPM.
We have generated broadband THz pulses within eight periods of InGaN/GaN quantum wells due to dipole radiation following generation of spatially-separated electrons and holes. Output powers as high as 1 μW have been obtained.
We have observed broadband quasi-phase-matched backward difference-frequency generation in short-period periodically-poled KTP, which can be used as a novel scheme for spectral phase conjugation.
Transverse-pumping geometry can be utilized for efficient generation of far-infrared radiation in 13–30 μm based on difference-frequency generation in periodically-poled LiNbO3 at its polariton resonances. High conversion efficiencies are achievable.
We have demonstrated that frequency upconversion in periodically-poled LiNbO3 is capable of reaching single-photon sensitivities for detections at 1.27 μm and 1.57 μm at room temperature.
We show that transverse-pumping geometry can be exploited for THz generation when a second-order nonlinear medium is highly lossy at its polariton resonance. High conversion efficiencies can be achieved via such a novel configuration.
We demonstrate that THz radiation beams generated by an array of the randomly-distributed InN nanopyramids can be used to enhance the THz output power by two orders of magnitude due to strong constructive interference.
We have observed unique polarization and azimuth-angle characteristics of THz waves, generated from anisotropic monoclinic GaTe when pump photon energy is below and above its bandgap, due to carrier unidirectional diffusion.
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