25 Gbps direct modulation and 10 km data transmission with 1310 nm waveband wafer fused VCSELs.

Direct modulation at >25 Gbps is achieved with 1310 nm wavelength wafer fused VCSELs by adjusting the strain in the quantum well active region and the cavity photon lifetime. 25 + Gbps large signal modulation with 10-12 BER at 1310 nm across 10 km of standard single mode fiber is demonstrated.

Polarization mode control of long-wavelength VCSELs by intracavity patterning.

Polarization mode control is enhanced in wafer-fused vertical-cavity surface-emitting lasers emitting at 1310 nm wavelength by etching two symmetrically arranged arcs above the gain structure within the laser cavity. The intracavity patterning introduces birefringence and dichroism, which discriminates between the two polarization states of the fundamental transverse modes. We find that the cavity modifications define the polarization angle at threshold with respect to the crystal axes, and increase the gain anisotropy and birefringence on average, leading to an increase in the polarization switching current. Experimental measurements are explained using the spin-flip model of VCSEL polarization dynamics.

8.5 W VECSEL output at 1270 nm with conversion efficiency of 59%.

We report on 1270 nm vertical-external-cavity surface-emitting lasers (VECSELs) with up to 59% conversion efficiency and maximum output power of 8.5 W (pump limited), at 5°C heat sink temperature. These VECSELs comprised wafer-fused gain mirrors in the flip-chip (thin-disk) heat dissipation scheme. The reflected pump light from the gain mirror surface was found to depend considerably on temperature and pump power.

Increasing single mode power of 1.3-µm VCSELs by output coupling optimization.

We report on the single mode emission power enhancement of 1.3-µm VCSELs by adjusting the reflectivity of the top GaAs-based DBR for output coupling optimization using selective removal of Bragg reflector layers. Devices with record single mode power of 6.8-mW at room temperature and 2.8-mW at 80°C, with more than 30 dB single mode suppression ratio, have been obtained.

Optical injection locking of transverse modes in 1.3-µm wavelength coupled-VCSEL arrays.

Optical injection locking of 1.3-µm phase-locked VCSEL arrays defined by patterned tunnel junctions and wafer fusion is investigated experimentally and theoretically. The impact of the overlap between the master laser injection beam and the injected modes is demonstrated and explained with a rate equation model that incorporates the spatial variations.

14XX nm-wavelength electrically-pumped VECSELs fabricated by wafer fusion.

We report on the design, fabrication and characterization of electrically pumped vertical external cavity surface emitting lasers (EP-VECSELs) emitting at 1470 nm. We demonstrate 6.2 mW of CW output power, which represents the highest power value reported so far for EP-VECSELs in the 14XX nm and 15XX nm wavelength bands.

1.38-µm mode-locked Raman fiber laser pumped by semiconductor disk laser.

A mode-locked Raman fiber laser pumped by 1.3 µm semiconductor disk laser is demonstrated. Direct Watt-level core-pumping of the single-mode fiber Raman lasers and amplifiers with low-noise disk lasers is demonstrated to represent a highly practical solution as compared with conventional scheme using pumping by Raman wavelength convertors. Raman laser employing passive mode-locking by nonlinear polarization evolution in normal dispersion regime produces stable pedestal-free 1.97 ps pulses at 1.38 µm. Using semiconductor disk lasers capable of producing high power with diffraction-limited beam allows Raman gain to be obtained at virtually any wavelength of interest owing to spectral versatility of semiconductor gain materials and wafer-fusing technology.

["Needle-to-scalpel"--the benefit of urgent CABG in significant left main coronary artery stenosis]. / "Timpul de la ac la bisturiu": beneficiul interventiei chirurgicale prompte in stenoza de trunchi de coronara stâng.

UNLABELLED: Left main coronary artery (LMCA) stenosis is a relatively infrequent but important cause of symptomatic coronary artery disease. The diagnosis of left main coronary artery disease is made by coronary angiography. Coronary artery bypass grafting is the first-line therapy, the standard treatment for LMCA stenosis, which improves the likelihood of survival, while percutaneous coronary intervention (PCI) is emerging as a possible alternative to surgery. We present the case of a patient with history and symptoms of stable angina pectoris, especially associated with exercise, variable threshold, since four years, and who describes a worsening of symptoms in the last month; the angina had become more frequent, more prolonged and occurred at a lower threshold. At about 20 hours from getting admitted to our hospital, the patient had severe and prolonged rest angina, associated with important changes on ECG, which led to the indication of emergency coronary angiography. This investigation showed severe left main coronary artery stenosis and significant lesions in other important vessels (three-vessel disease), in a patient with normal left ventricular function. The recurrence and the intensity of prolonged angina of our patient have necessitated urgent myocardial revascularization surgery with quadruple coronary-artery bypass grafting. After surgery, the patient was asymptomatic and he was discharged 8 days after in a good clinical state. CONCLUSIONS: The advantage of coronary artery bypass grafting performed as urgent surgery for the treatment of our patient with left main coronary artery stenosis and concomitant acute coronary syndrome, shortly after coronary angiography, was obvious, significantly improved the clinical outcome, without postoperative ischemic complications.

[Vasospastic angina]. / Angina vasospastica. Teste de provocare a spasmului coronarian.

Vasospastic angina is associated with ventricular arrhythmias, acute myocardial infarction and sudden arrhythmic death. The main ischemic mechanism in vasospastic angina is coronary spasm. Because the demonstration of spontaneous coronary spasm is difficult, a number of methods which can provoke spasm in susceptible patients were imagined. The most used clinical methods of diagnostic provocation testing were analyzed.

Long-term outcome of patients with very long stents for treatment of diffuse coronary disease.

OBJECTIVES: The study sought to determine the 6-month clinical outcome of patients who underwent implantation of very long coronary stents to treat diffuse disease and/or long dissections and to compare the findings with those reported in the literature for patients who underwent implantation of multiple short coronary stents. BACKGROUND: New designs of flexible stents enable the implantation of long stents rather than multiple short, older design stents. The initial experience is very promising but the long-term outcome has not been described yet. METHODS: Fifty-seven consecutive patients in whom 67 long stents (>/=30 mm) were successfully deployed were included in this study. Six-month clinical and angiographic follow-up was prospectively collected. Patients with recurrent angina underwent coronary angiography without further testing. Patients who remained asymptomatic at the 6-month follow-up visit underwent positron emission tomographic imaging, and those with results suggestive of ischemia underwent coronary angiography. A combined study end point was defined as death, myocardial infarction, and the need for target vessel revascularization. RESULTS: Only 1 patient (2%) reached a study end point at hospital discharge. An additional 20 patients (total 21 patients [37%]) reached an end point by 6 months. The outcome was not influenced by the clinical presentation (stable or unstable angina) or by the indication for stenting (elective or emergency). Predictors for adverse outcome were multiple stents per narrowing (63% vs 29%, P <. 04), and stents smaller than 3.5 mm (49% vs 22%). Narrowing and stent length were not predictive of a study end point in narrowings that were successfully treated by a single long stent. CONCLUSIONS: Elective stenting provides an effective solution for patients with diffuse coronary disease provided that a single long stent (usually <40 mm) can cover the full length of the narrowing. The results are better when vessels larger than 3 mm are treated. Compared with multiple short stents, implantation of a single long stent is probably at least as effective, and the procedure is quicker and cheaper and thus should be the preferred approach.

New indicator for stent covering area.

A small gap between stent struts is essential to support the vessel wall, prevent elastic recoil, and prevent intimal flaps from prolpasing into the lumen. We defined Gap Index as the ratio of strut width divided by the percent of the vessel wall area covered by the stent metal, and proved mathematically that this index relates inversely to the total length of stent struts (or coil), and directly related to stent cell size. Twenty-four (12 tubular and 12 coil) stents from 17 manufacturers were analyzed. Strut width in the tubular and coil groups was 354.1 +/- 276.0 and 955.9 +/- 553.9 microm, respectively (P < 0.001). The relative metallic surface area (RMS) in the tubular and coil groups for 3 mm stent diameter was 16.0 +/- 4.6 and 10.6 +/- 3.7%, respectively (P < 0.005). Great variations in Gap Index were found amongst different stents, with up to 100-fold. Gap Index in the tubular and coil groups for 3 mm stent diameter was 24.4 +/- 21.7 and 105.8 +/- 97.5 units, respectively (P = 0.001). Thus, coil stents have a smaller relative metallic surface area despite increased strut width. This is the result of reduced total strut length and fewer and larger cells, as represented by a higher Gap Index. This information may be useful for new stents designs.

Initial experience with long coronary stents: the changing practice of coronary angioplasty.

The initial experience with the use of long coronary stents (> 30 mm in length) was analyzed retrospectively. Sixty-seven stents were deployed in 58 narrowings in 57 patients (34 AVE Microstents, 16 Nir stents, four Gianturco-Roubin II stents, and 13 Wallstents). Stents were implanted in 22 patients with unstable angina, 34 patients with stable angina, and one patient during direct angioplasty for acute myocardial infarction. Eighteen additional short stents were implanted to cover the entire length of the lesions so that an average of one and a half stents were deployed per patient. The length of the narrowings before stenting was 40 +/- 20 mm and the length of the stented segments was 45 +/- 20 mm. Stents were deployed for "bailout" in 23 narrowings, to improve suboptimal results of balloon angioplasty in 18 narrowings, and electively in 17 narrowings. Twenty of the 67 long stents were deployed in saphenous vein grafts. The success rate of stent implantation was 100%. One patient had a rupture of a saphenous vein graft after deployment of two long stents, with tamponade treated by emergency surgery. One patient had chest pain 18 hours after stent deployment; by the time he arrived at the catheterization laboratory the pain had subsided and the angiogram revealed a patent artery with normal flow. There were no other major complications during the hospital course and 1-month follow-up. We conclude that long coronary stents can be deployed successfully in native coronary arteries and vein grafts. They are useful for elective implantation and extremely helpful in bailout situations. The immediate results are excellent, but long-term outcome is awaited.

[Myelodysplastic syndromes. A clinico-biological analysis of 27 cases]. / Sindroame mielodisplazice. Analiza clinico-biologica a 27 de cazuri.

A series of 27 patients with myelodysplastic syndrome (MDS) was analysed to determine the clinical and pathologic features, the natural history and the prognostic factors. The clinical features of these patients included the following: mean age 53.77 years; symptoms due to cytopenias 100 per cent; hepatomegaly 44.5 per cent; splenomegaly 11 per cent. Almost all patients with MDS presented anemia; additional cytopenias were present in many patients. The bone marrow was hypocellular in 1/3 of cases. The patients have been classified according to the French-American-British (FAB) Group criteria: there were 11 patients with refractory anemia, 11 patients with refractory anemia with sideroblasts and 5 patients with refractory anemia with excess of blasts. The mean survival was 19 months, 9 patients died: death was due to infection or hemorrhage in 7 cases and to evolution to acute myelogenous leukemia (AML) in 2 cases (10.5%). Thrombocytopenia, the Bournemouth scoring system and FAB classification were independent prognostic factors.