Photon statistics of a single mode of spontaneous Raman scattering in a distributed Raman amplifier
Experimental measurement of spontaneous noise statistics from a distributed Raman amplifier has been achieved with single-mode and single-photon resolution. The results agree with quantum theoretical predictions of a Bose-Einstein probability distribution. Distributed Raman amplification is becoming increasingly important in today's optical communication systems. It improves the optical signal-to-noise ratio by providing optical gain inside the transmission fiber.
Observation of macroscopic quantum fluctuations in stimulated Raman scattering (A)
Large-scale quantum fluctuations have been observed in the energy of light pulses produced by transient stimulated Raman scattering of laser pulses in hydrogen gas. This experiment verifies recent theoretical work on quantum initiation of light scattering, and provides an example of a macroscopic system which begins in a pure state and, through essentially pure-state quantum evolution, ends up having highly unpredictable values of its physical observables.
EFFECT OF SAMPLE PREPARATION ON WATER TREE RESISTANCE OF XLPE/SEBS BLENDS
The effects of an aromatic polymer, such as poly[styrene-b-(ethylene-co-butylene)b-styrene] (SEBS), and its preparation processes on water tree resistance, morphology, crystallinity, dielectric constant and dielectric loss tangent of crosslinked polyethylene (XLPE)/SEBS and XLPE/SEBS/ethylene vinyl acetate (EVA) blends were investigated. The XLPE/SEBS samples were characterized by means of differential scanning calorimetry, scanning electron microscopy, dielectric spectral analysis and the accelerated water treeing experiment. The results clearly showed that although SEBS was partially compatible with LDPE and it was dispersed evenly in XLPE matrix, the blends demonstrated excellent dielectric performances, such as dielectric constant and dissipation factor. The crystallinity of XLPE/SEBS blends was decreased with increase in SEBS content and it was further decreased with the addition of EVA. SEBS could effectively improve the water-tree resistance of XLPE and both SEBS and EVA were found to improve the water tree resistance of XLPE synergistically as expected. The differences in sample preparation processes could change the phase morphology and dielectric performance of the blends, and could also influence the dispersion of SEBS in XLPE matrix as well as the crystallinity of the blends. Different preparation processes led to different water tree resistance behaviours of the samples. The improvement of SEBS dispersion in XLPE matrix helped to improve the water tree resistance of XLPE.