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The infrared real-time temperature measure by a PbSe sensor with high spatial resolution via aspheric optics has been exploited to control temperature-sensitive material microprocessing. Applications in the range from 370 K to 800 K has been discussed.
We observed phase-matched frequency mixing of a THz wave with a near-infrared laser beam in a ZnGeP2 crystal. Such a process can be used to detect a THz wave in the range of 91-139 mum.
Terahertz emission is observed from ferromagnetic GaMnAs when the samples are excited at normal incidence with 3.1 eV, 130 fs laser pulses. We demonstrate experimentally that the radiation is directly related to the sample magnetization.
Dicke narrowing dominates over collisional dephasing in gas phase H2 up to 500 Torr, permitting the efficient production of a record 70,000 cm-1 broad Raman sideband spectrum by molecular modulation at room temperature.
We have measured thermal conductivity of Y3Al5O12, GdVO4, and YVO4. It was found that YVO4 has larger thermal conductivity than GdVO4. Nd3+-doping effect in thermal conductivity and thermal expansion ratio have been also discussed.
Time-resolved mid-infrared pump-probe measurements in a quantum cascade laser operating above threshold reveal gain recovery dynamics to be two-fold: relaxation within a stage on a sub-picosecond scale and transport between stages on a picosecond scale.
We demonstrate uncooled 2.5 Gb/s operation up to 110degC of 1.3 mum GaInNAs double quantum well lasers with low threshold current and excellent temperature stability.
Heating a photo-darkened ytterbium fiber causes a recovery in spectral transmission to the pre-darkened state. Exposure to H2 at high temperatures causes a permanent change in the visible transmission identical to that caused by photo-darkening.
We present our recent work on THz devices, including THz quantum cascade lasers and in particular focusing on THz quantum well photodetectors. Background limited performance has been achieved covering a wide range of THz spectrum.
Coherent dynamics of vibrational modes in gold nanoshells is studied by means of ultrafast pump-probe spectroscopy. A theoretical model is developed that provides a good agreement with experimental data.
We map a laserpsilas internal temperature structure for the first time, identifying separate heat sources due to contact heating and nonradiative recombination and using this technique to compare degradation mechanisms for GaAs-based and Si-based lasers.
We demonstrate the formation of long period gratings in fluid-filled photonic bandgap fiber (PBGF). The unique modal properties of PBGFs allow for coupling to LP11-like modes at multiple wavelengths. We obtain good agreement with simulations.
We experimentally demonstrate that acoustic-phonon attenuation in water described by a classic continuum-elastic model fails for sub-THz acoustic frequencies. A dynamic measurement technique for ice-water interface position with a ~10nm resolution will also be presented.
We have successfully determined the anharmonic decay time of coherent longitudinal-acoustic-phonons in GaN. The temperature dependent anharmonic decay behavior is found to agree well with the Herringpsilas theory even up to the sub-THz frequency regime.
Ultrafast electron dynamics in quasi-one-dimensional NbSe3 conductors was investigated by means of two-color pump-probe reflectivity measurements. The results clearly demonstrate the resonant probing of the charge-density-wave phases with different transition properties.
High spatial and thermal resolution measurements of the surface temperature of an operating single-mode oxide-confined VCSEL are reported. We show that the beam waist scales with the focal length of the thermal lens.
This paper demonstrates the performance of planar geometry InGaAs/InP avalanche diodes, specifically designed and fabricated for Geiger-mode operation at wavelengths around 1550 nm, in terms of dark count rate, single-photon detection efficiency, afterpulsing and photon-timing jitter.
The first experimental measurement of electron spin relaxation in GaInNAs quantum wells is reported. An all-optical polarization switch based on the excitation of spin-polarized electrons is demonstrated.
Optimized single stripe 975-nm broad area devices deliver 76% power conversion efficiency at 10degC. Cooling the material leads to 85% efficiency at -50degC. External differential quantum efficiency is the dominant term.
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