Abstract
Optical immersion clearing is a technique that has been widely studied for more than two decades and that is used to originate a temporary transparency effect in biological tissues. If applied in cooperation with clinical methods it provides optimization of diagnosis and treatment procedures. This technique turns biological tissues more transparent through two main mechanisms - tissue dehydration and refractive index (RI) matching between tissue components. Such matching is obtained by partial replacement of interstitial water by a biocompatible agent that presents higher RI and it can be completely reversible by natural rehydration in vivo or by assisted rehydration in ex vivo tissues. Experimental data to characterize and discriminate between the two mechanisms and to find new ones are necessary. Using a simple method, based on collimated transmittance and thickness measurements made from muscle samples under treatment, we have estimated the diffusion properties of glucose, ethylene glycol (EG) and water that were used to perform such characterization and discrimination. Comparing these properties with data from literature that characterize their diffusion in water we have observed that muscle cell membrane permeability limits agent and water diffusion in the muscle. The same experimental data has allowed to calculate the optical clearing (OC) efficiency and make an interpretation of the internal changes that occurred in muscle during the treatments. The same methodology can now be used to perform similar studies with other agents and in other tissues in order to solve engineering problems at design of inexpensive and robust technologies for a considerable improvement of optical tomographic techniques with better contrast and in-depth imaging.

Abstract
To determine the differences between the optical clearing effects created by ethylene glycol in fresh and frozen samples, we have performed several measurements from samples in both conditions. Fresh samples were used after animal sacrifice and frozen samples were kept at -20 degrees C for 72 hours. The different measurements performed with samples from both cases were total transmittance, collimated transmittance, total reflectance and specular reflectance. Considering, for instance, collimated transmittance measurements, we have verified that the spectra measured from both samples before adding the solution present different levels of collimated transmittance. The time-dependence evolution of the collimated transmittance spectrum is similar between both cases of samples, but since they present different levels of "natural" transmittance, the optical clearing effect is observed at different levels if we compare between fresh and frozen samples.

Abstract
We obtained a propagation equation for an optical pulse at an electromagnetically induced transparency window guided on a gas-filled hollow-core photonic crystal fiber. This equation admits dissipative solitons whose analytical expression was also obtained. Depending on the parameter region, they may be stable or unstable. We simulated a typical experimental arrangement and found some cases for which the equation parameters are such that it admits stable solitons.

Abstract
We developed an experimental setup for electromagnetically induced transparency able to manufacture microcells, suitable for optical fiber communications technology. A hollow-core photonic crystal fiber (HC-PCF) is filled with acetylene, to work in the 1500 nm telecommunications window. We used a HC-PCF with the mode-field diameter compatible with standard single-mode fibers, with the purpose of achieving low-loss splicing and enabling us to work at low pumping powers. This allows to induce a narrow transparency window, which can be spectrally adjusted and dynamically controlled. (c) 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:348-352, 2015

Abstract

Abstract
We have obtained spectral broadening by pumping a nonmicrostructured highly nonlinear fiber with a continuous wave signal from a Raman fiber laser. The experiment was simulated using a generalized Schrodinger equation containing the actual Raman response of the fiber as calculated from the experimental Raman gain. A different input-noise model, that reproduces well the power spectral density of the laser, was used and compared with others previously proposed. (C) 2013 Optical Society of America