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Phonon-polariton resonances are manifestation of the strong interaction between an electromagnetic wave interacts and transverse-optical phonons in a crystalline solid. Such resonances result in great enhancements of ionic second-order nonlinearities [1]. For LiNbO3, dominant element of the ionic second-order nonlinear susceptibility tensor coefficients d33 at 7.5 THz is a factor of about 50 larger...
We have shown that Raman oscillation, frequency upconversion, and Raman amplification can be achieved in a second-order nonlinear medium at the phonon-polariton resonance.
We have observed enhancements of forward and backward anti-Stokes Raman signals generated in lithium niobate waveguides by one order of magnitude. Forward and backward exhibit different spectral features, unique for two configurations.
We have observed frequency upconversion of the incoming photons within the communication band to a visible band in a gallium phosphide crystal. Such a crystal is capable of reaching the single-photon detection level.
Laser cooling of solids based on anti-Stokes photoluminescence was proposed in 1929 [1]. Indeed, through the light emission based on phonon-assisted anti-Stokes photoluminescence, the average photon energy emitted is larger than that for the absorbed pump photons. The difference between the emitted and absorbed photon energies is made up by the energy of each removed phonon. Since phonons represent...
We have observed enhancement factors of at least 21 for backward-propagating anti-Stokes Raman signals generated by Ti-diffused lithium niobate waveguides under the microwatt pump power and using a single-photon detector.
We implemented single-photon detector in 1500-nm band based on frequency up-conversion in nonlinear waveguide at pump wavelength of 1920 nm. Ultralow dark count rate and signal photon detection rate are 20 s−1 and 56.8 s−1.
Anti-Stokes photoluminescence (ASPL) of n-type GaN is observed at room temperature. By studying behaviors of ASPL, the mechanism is identified as phonon-assisted bandtail photoluminescence. Such a process results in laser cooling.
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.
We have implemented a single-photon detector in the 1500-nm band based on frequency up-conversion in a MgO-doped periodically-poled LiNbO3 waveguide, with a record-low dark count rate and a record-low detectable signal photon rate.
MgO-doped periodically-poled LiNbO3 waveguide is used to up-convert photons at 1.535–1.568 μm to those at 598–603 nm, which can be detected by avalanche photodetector at single-photon counting level. Conversion efficiencies up to 45% are achieved.
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.
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