Less than 1% quantum defect fiber lasers via ytterbium-doped multicomponent fluorosilicate optical fiber

Two ytterbium-doped fiber lasers exhibiting quantum defects of less than 1% are demonstrated, in which pumping at wavelengths of 976.6 and 981.0 nm yielded lasing at wavelengths of 985.7 and 989.8 nm, respectively. The multicomponent fluorosilicate active optical fiber, fabricated using the molten core method, has spectral characteristics similar to those of fluoride glasses, namely short average emission wavelength and long upper state lifetime. A best-case slope efficiency of 62.1% was obtained, matching the theoretical model very well. With further fiber and laser optimization, slope efficiencies approaching the quantum limit should ultimately be possible. A reduction in the quantum defect may offer significant mitigation of issues associated with fiber heating. As such, this work can serve as a possible direction for future scaling of high-power fiber laser systems.

Highly nonlinear yttrium-aluminosilicate optical fiber with a high intrinsic stimulated Brillouin scattering threshold

Highly nonlinear (high-NA small-mode-area) optical fibers also possessing an intrinsically high stimulated Brillouin scattering threshold are described. More specifically, silica clad, yttrium-aluminosilicate core fibers are shown to exhibit an intrinsically low Brillouin gain coefficient between 0.125 and 0.139×10^-11  m/W and a Brillouin gain linewidth of up to 500 MHz. Losses on the order of 0.7 dB/m were measured, resulting from impurities in the precursor materials. Nonlinear refractive index values are determined to be similar to that of silica, but significant measurement uncertainty is attributed to the need to estimate dispersion curves since their direct measurement could not be made. The interest for highly nonlinear optical fibers with a low intrinsic Brillouin gain coefficient is expected to continue, especially with the growing developments of narrow-linewidth high-energy laser systems.

Brillouin scattering properties of lanthano-aluminosilicate optical fiber

Utilizing measurements on a lanthano-aluminosilicate core optical fiber, the specific effects of lanthana (La₂O₃) on the Brillouin characteristics of silica-based oxide glass optical fibers are described. Lanthana is an interesting species to investigate since it possesses a wide transparency window covering the common fiber laser and telecom system wavelengths. As might be expected, it is found that the properties of lanthana are very similar to those of ytterbia (Yb₂O₃), namely, low acoustic velocity, wide Brillouin spectral width, and a negative photoelastic constant, with the latter two properties affording significant reductions to the Brillouin gain coefficient. However, lanthana possesses thermo-acoustic and strain-acoustic coefficients (acoustic velocity versus temperature or strain, TAC and SAC, respectively) with signs that are opposed to those of ytterbia. The lanthano-aluminosilicate (SAL) fiber utilized in this study is Brillouin-athermal (no dependence of the Brillouin frequency on temperature), but not atensic (is dependent upon the strain), which is believed to be, to the best of our knowledge, the first demonstration of such a glass fiber utilizing a compositional engineering approach.

Brillouin spectroscopy of a novel baria-doped silica glass optical fiber

Presented here for the first time to the best of our knowledge is a detailed Brillouin spectroscopic study of novel, highly-BaO-doped silica glass optical fibers. The fibers were fabricated utilizing a molten-core method and exhibited baria (BaO) concentrations up to 18.4 mole %. Physical characteristics such as mass density, acoustic velocity, visco-elastic damping, and refractive index are determined for the baria component of the bariosilicate system. It is found that, of each of these parameters, only the acoustic velocity is less than that of pure silica. The effect of temperature and strain on the acoustic velocity also is determined by utilizing estimates of the strain- and thermo-optic coefficients. The dependencies are found to have signs opposite to those of silica, thus suggesting both Brillouin-frequency a-thermal and a-tensic binary compositions. Via the estimate of the strain-optic coefficient and data found in the literature, the Pockels' photoelastic constant p(12) is estimated, and both a calculation and measured estimate of the Brillouin gain versus baria content are presented. Such novel fibers incorporating the unique properties of baria could be of great utility for narrow linewidth fiber lasers, high power passive components (such as couplers and combiners), and Brillouin-based sensor systems.

[Septic shock in a patient with the Fournièr gangrene with fatal outcome]

AIM

The authors present a case of a patient with developed Fournièr gangrene and septic shock. Fournièr gangrene belongs to the group of local non-specific infection of soft tissues (NSTI). Its incidence is relatively low, but the infection is extraordinary aggressive with a possible lethal end.

MATERIAL AND METHOD

39 years old patient with 4 days history of Fournier gangrene's development was admitted in irreversible septic shock. The initial APACHE II score was 36. The delay in treatment was an important factor in the further course of illness with lethal end.

RESULTS

Above the mentioned 39 years old patient died because of septic shock. The hemorrhagic cystitis was the original source of infection with further development of Fournièr gangrene according to the pathological record.

CONCLUSION

We often come across all different kinds of stages of sepsis from the MODS to the septic shock for patients with Fournièr gangrene. Causal treatment should be started early. The local surgical excision and wide broad antibiotic administrations are basic treatments in the context of other treatment modalities according to the current patient's needs. The adjuvant hyperbaric oxygen treatment takes place in patients with Fournièr gangrene as well and is beneficial. The following factor even worsens the illness prognosis: delay in diagnostic, higher age, anorectal origin of infection, the amount of organ with dysfunction or failure, diabetes mellitus and significant immunodeficiency.

Sexual experience effects are blocked both by the protein-synthesis inhibitor, cycloheximide, and by the noncompetitive NMDA antagonist, MK-801

Three studies were done to determine the effects of a brief 2-h sexual experience on the maintenance of sexual behavior in male rats; the effects on the experience-based maintenance of sexual behavior of gonadal hormones (study 1), a protein-synthesis inhibitor (study 2), and an N-methyl-D-aspartate receptor blocker (study 3) were determined. Naive male rats were provided with a 2-h sexual experience with sexually receptive hormonally "primed" females or they received no experience. In the first study animals under each of these conditions then underwent castration or sham surgery. In the second study animals under each of the experience conditions received either cycloheximide (CYX) or saline (SAL; 1.5 or 3.0 mg/kg CYX or SAL sc, 10 min after the experience). In study 3 experienced and inexperienced animals received either 0.07 or 0.10 mg/kg MK-801 ip (15 min before the experience). In all studies animals were tested for sexual behavior 3, 6, and 9 days after surgery or injection. These studies showed that the most consistent effect of a 2-h sexual experience was to facilitate the initiation of mounting, especially on the first test; they show, further, that most experience effects were reduced or eliminated if animals were castrated between experience and test, if they received a drug (CYX) at the time of the experience that blocks the synthesis of proteins, or if they received an NMDA receptor antagonist prior to the experience.