Sign phase transition and directed paths in random media

JETP Letters ◽  
1996 ◽  
Vol 64 (4) ◽  
pp. 312-318 ◽  
Author(s):  
B. Spivak ◽  
S. Feng ◽  
F. Zeng
Keyword(s):  
Phase Transition ◽  
Random Media ◽  
Directed Paths

scholarly journals A Self-Consistent Quantum Field Theory for Random Lasing

2019 ◽  
Vol 9 (12) ◽  
pp. 2477 ◽  
Author(s):  
Andreas Lubatsch ◽  
Regine Frank
Keyword(s):  
Phase Transition ◽  
Random Media ◽  
Theoretical Method ◽  
Pump Intensity ◽  
Stimulated Emission ◽  
Random Laser ◽  
Central Feature ◽  
Quantum Field ◽  
Random Lasing ◽  
Correlation Volume

The spatial formation of coherent random laser modes in strongly scattering disordered random media is a central feature in the understanding of the physics of random lasers. We derive a quantum field theoretical method for random lasing in disordered samples of complex amplifying Mie resonators which is able to provide self-consistently and free of any fit parameter the full set of transport characteristics at and above the laser phase transition. The coherence length and the correlation volume respectively is derived as an experimentally measurable scale of the phase transition at the laser threshold. We find that the process of stimulated emission in extended disordered arrangements of active Mie resonators is ultimately connected to time-reversal symmetric multiple scattering in the sense of photonic transport while the diffusion coefficient is finite. A power law is found for the random laser mode diameters in stationary state with increasing pump intensity.

Temperature-tunable scattering strength based on the phase transition of liquid crystal infiltrated in well-defined macroporous random media

2007 ◽  
Vol 29 (8) ◽  
pp. 949-954 ◽  
Author(s):  
Shunsuke Murai ◽  
Koji Fujita ◽  
Takayuki Hirao ◽  
Kazuki Nakanishi ◽  
Kazuyuki Hirao
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Random Media ◽  
Strength Based ◽  
Scattering Strength

scholarly journals Sign phase transition in the problem of interfering directed paths

2018 ◽  
Vol 97 (1) ◽  
Author(s):  
C. L. Baldwin ◽  
C. R. Laumann ◽  
B. Spivak
Keyword(s):  
Phase Transition ◽  
Directed Paths

scholarly journals A Self-Consistent Quantum Field Theory for Random Lasing

2019 ◽  
Author(s):  
Andreas Lubatsch ◽  
Regine Frank
Keyword(s):  
Phase Transition ◽  
Random Media ◽  
Theoretical Method ◽  
Stimulated Emission ◽  
Random Laser ◽  
Central Feature ◽  
Quantum Field ◽  
Random Lasing ◽  
Laser Mode ◽  
Laser Modes

The spatial formation of coherent random laser modes in strongly scattering disordered random media is a central feature in the understanding of the physics of random lasers. We derive a quantum field theoretical method for random lasing in disordered samples of complex amplifying Mie resonators which is able to provide self-consistently and free of any fit parameter the full set of transport characteristics at and above the laser phase transition. The coherence length and the correlation volume respectively is derived as an experimentally measurable scale of the phase transition at the laser threshold. We find that the process of stimulated emission in extended disordered arrangements of active Mie resonators is ultimately connected to time-reversal symmetric multiple scattering in the sense of photonic transport while the diffusion coefficient is finite. A power law is found for the random laser mode diameters in stationary state with increasing pump intensity.

Microstructure of laser-irradiated, conducting Kapton polyimide

1995 ◽  
Vol 53 ◽  
pp. 502-503
Author(s):  
D. L. Callahan ◽  
Z. Ball ◽  
H. M. Phillips ◽  
R. Sauerbrey
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
Transmission Electron Microscopy ◽  
Cross Section ◽  
Film Surface ◽  
Cross Sectional ◽  
General Utility ◽  
Transmission Electron ◽  
Considerable Debate ◽  
Potential Applications

Ultraviolet laser-irradiation can be used to induce an insulator-to-conductor phase transition on the surface of Kapton polyimide. Such structures have potential applications as resistors or conductors for VLSI applications as well as general utility electrodes. Although the percolative nature of the phase transformation has been well-established, there has been little definitive work on the mechanism or extent of transformation. In particular, there has been considerable debate about whether or not the transition is primarily photothermal in nature, as we propose, or photochemical. In this study, cross-sectional optical microscopy and transmission electron microscopy are utilized to characterize the nature of microstructural changes associated with the laser-induced pyrolysis of polyimide.Laser-modified polyimide samples initially 12 μm thick were prepared in cross-section by standard ultramicrotomy. Resulting contraction in parallel to the film surface has led to distortions in apparent magnification. The scale bars shown are calibrated for the direction normal to the film surface only.

The structure of membranes and membrane proteins embedded in amorphous ice

1992 ◽  
Vol 50 (1) ◽  
pp. 432-433
Author(s):  
Uwe Lücken ◽  
Joachim Jäger
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Membrane Proteins ◽  
Phase Transition Temperature ◽  
Lipid Vesicles ◽  
Freezing Stress ◽  
Amorphous Ice ◽  
Different Temperatures ◽  
Band Pass ◽  
Lipid Polymorphism

TEM imaging of frozen-hydrated lipid vesicles has been done by several groups Thermotrophic and lyotrophic polymorphism has been reported. By using image processing, computer simulation and tilt experiments, we tried to learn about the influence of freezing-stress and defocus artifacts on the lipid polymorphism and fine structure of the bilayer profile. We show integrated membrane proteins do modulate the bilayer structure and the morphology of the vesicles.Phase transitions of DMPC vesicles were visualized after freezing under equilibrium conditions at different temperatures in a controlled-environment vitrification system. Below the main phase transition temperature of 24°C (Fig. 1), vesicles show a facetted appearance due to the quasicrystalline areas. A gradual increase in temperature leads to melting processes with different morphology in the bilayer profile. Far above the phase transition temperature the bilayer profile is still present. In the band-pass-filtered images (Fig. 2) no significant change in the width of the bilayer profile is visible.

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