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Laser induced breakdown (LIB) in air has been explained by different ways along pulse width τ. Cascade ionization (CI) is considered as the mechanism for long pulse widths of over 1 ns. On the other hand, laser filamentation is alternative mechanism of air-breakdown for fs pulses, because CI processes based on collision cannot play a role in fs pulses. However, for intermediate ps pulse region, the...
We demonstrated CW SHG at 400 nm in a first-order QPM adhered slab waveguide with a periodically-poled Mg-doped stoichiometric lithium tantalate core. The measured SHG normalized conversion efficiency was 34.7%/W for a 20 mm length.
We report improved thermal performance in the heat-removal module for stable wavelength conversion, fabricated by a new method, air-bubble reduction. The quantitative relation between focusing position, normalized conversion efficiency and effective heat capacity is investigated.
We demonstrated RGB laser sources by optical-parametric-generation using first-order quasi-phase-matched adhered slab waveguides with a periodically-poled Mg-doped stoichiometric lithium tantalate core. We also examined the extensible spectral bandwidth by chirped periods against speckle with simulation.
Thermal management is discussed in single-pass CW SHG in QPM Mg:SLT. Effective heat capacity in four-side heat removal module is quantitatively characterized by Phase-Matched Calorimetry and enhanced by 50% with narrowing device width.
We report the observation of the broadest frequency correlation of two-photon states to date via parametric down conversion using chirped QPM device. The two-photon correlation in time domain can be compressed to 3.3 cycles.
We report sum-frequency-photon generation from an entangled photon pair, which is an important step toward the realization of photon pairs with ultra-short (monocycle) temporal correlation.
We present thermal effects in single pass CW SHG with focused Gaussian beams. Thermal dephasing and lensing effects depending on the SH power are demonstrated with the calculated temperature change in PPMgSLT crystals.
The state-of-art technology of a quasi-phase matched (QPM) device has enabled the efficient generation of frequency-entangled photon pairs through parametric fluorescence [1, 2]. Harris [3] has proposed the generation of photon pairs which are correlated on a mono-cycle time scale of optical period. In that paper, the poling period of QPM device is linearly chirped (increased) from the entrance to...
We derived an expression for the noise between the diffraction orders from a random grating. The result was applied to analyze the statistical duty-cycle error in PPLN, providing an efficient means for poling quality evaluation.
We demonstrate an efficient far-field diffraction method for quality assessment of periodically poled lithium niobate crystals. Microscopic and macroscopic analyses are carried out to obtain important statistical quantities and to assess the final device performance.
For accurate index measurement, we investigated Fabry-Perot type interference from optical wafers. Since this method is insensitive to environmental perturbation and simple to implement, it can be used to establish dispersion formula for newly developed optical materials.
We demonstrate that the nonlinear optical performance of periodically poled crystals can be exactly predicted by observing the far-field diffraction pattern. The diffraction pattern is shown to be equivalent to the second-harmonic generation tuning curve.
We report ultra-broad optical parametric gain spectra centered at near infrared in periodically poled congruent LiNbO3 and stoichiometric LiTaO3 crystals, using group-velocity matching near the degeneracy point. They can be useful for ultra-fast pulse applications.
We report ultra-broad optical parametric gain spectra centered at near infrared in periodically poled congruent LiNbO3 and stoichiometric LiTaO3 crystals, using group-velocity matching near the degeneracy point. They can be useful for ultra-fast pulse applications.
We present a method to measure the index of refraction of a wafer-type material accurately by using a modified Michelson interferometer. With this method, the difference between the refractive index of the ordinary-wave and that of the extraordinary-wave in the representative nonlinear crystal, LiNbO3 could be measured with ease.
We observed simultaneous red, green and blue light generated from periodically poled lithium niobate pumped with single picosecond laser. This process could be realized by a broadband design of the optical parametric generation of participating infrared frequencies. Pumping wavelength, pulse width, and quasi-phase-matching period were important parameters for this design.
Amplified spontaneous emission (ASE) associated with excited-state intramolecular proton transfer (ESIPT) was investigated in a single crystal and a glass of acetic acid 2-{4-[2-(2-hydroxy-phenyl)-4,5-diphenyl-imidazole-1-yl]-phenyl}-ethyl ester molecules. The polarization-dependent ASE was analyzed in an effort to understand the structural evolution involved in the ESIPT photo-cycle. From the analysis...
We demonstrated simultaneous red, green and blue light generation in periodically poled lithium niobate pumped with single picosecond laser. The primary color peaks were temperature-insensitive owing to broadband optical parametric generation of participating infrared frequencies.
We demonstrated simultaneous red, green and blue light generation in periodically poled lithium niobate pumped with single picosecond laser. The primary color peaks were temperature-insensitive owing to broadband optical parametric generation of participating infrared frequencies.
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