A self-protected colorless WDM-PON with 2.5 Gb/s upstream signal based on RSOA.

In this investigation, we propose and demonstrate a colorless wavelength division multiplexed passive optical network (WDM-PON) at 2.5 Gb/s using reflective semiconductor optical amplifier (RSOA)-based optical networking units (ONUs); together with a self-protected architecture against fiber fault. In the optical line terminal (OLT), we use an array of self-seeding Fabry-Perot laser diodes (FP-LDs) to provide single-longitudinal-mode (SLM) continuous wave (CW) optical sources for the external injection to the RSOA-based ONUs. The self-survivable function for protecting the fiber fault in the distributed fibers and the proposed network performance are investigated and discussed.

Tunable S-band erbium-doped triple-ring laser with single-longitudinal-mode operation.

We propose and demonstrate a tunable and stable single-longitudinal-mode (SLM) erbium fiber laser with a passive triple-ring cavity structure in S-band operation. The proposed laser is fundamentally structured by using three different lengths of ring cavities, which serve as the mode filters. When a mode-restricting intracavity fiber Fabry-Perot tunable filter (FFP-TF) is combined, the proposed resonator can guarantee a tunable and stable SLM laser oscillation. Moreover, the performances of the output power, wavelength stability, tuning range, and side-mode suppression ratio (SMSR) are studied.

Randomization of heavily damaged regions in annealed low energy Ge(+)-implanted (001)Si.

Apparent growth of amorphous layers during low temperature annealing was observed in low energy Ge(+)-implanted (001)Si by high-resolution transmission electron microscopy. The occurrence of abnormal growth is due to the randomization of heavily damaged regions beneath the original amorphous/crystalline interfaces. The randomization process is attributed to the strain, incurred by the presence of a high density of large Ge atoms in the heavily damaged Si substrate, relaxation to lower the free energy of the systems. The randomization upon annealing may be fruitfully applied to minimize the transient enhanced diffusion in shallow junction formation.

Diffractive optical element designed by use of an irregular etching-depth sequence.

In fabricating a diffractive optical element the ratio of the etching depth between the (n - 1)th and the nth mask is usually 1/2. We found that the diffraction efficiency of a diffractive optical element can be improved by as much as 7.8% if the above ratio (1/2) is not kept constant. For achieving this improvement the difference between the desired and the actual diffraction pattern is also used as an objective function for phase quantization.

An ultra-precision XYtheta(Z) piezo-micropositioner. I. Design and analysis.

A novel three degree-of-freedom micropositioner was developed for deep ultraviolet lithography applications. The design of the micropositioner utilizes the monolithic flexural mechanism with built-in multilayer piezoelectric actuators and sensors to achieve translations in the X- and Y-axes and rotation in the theta(Z)-axis. The compact design aims at high resolution, high stiffness, and extremely low crosstalk interference. Parametric analyses of harmonic and forced vibrations are conducted to solve the derived dynamic models for the near optimum geometry of the micropositioner. Furthermore, the error budget analysis is conducted to minimize the effects of the geometric tolerance, material variation, and hysteresis errors.

An ultra-precision XYTheta(Z) piezo-micropositioner. II. Experiment and performance.

For pt I see ibid., vol. 46, no. 4 (July 1999). The performance of an ultra-precision three dimensional micropositioner using the built-in multilayer piezoelectric actuators and sensors is presented. The compact design utilizes the monolithic mechanism to achieve translation in the X- and Y-axes and rotation in the theta(Z) axis with high stiffness and high damping. Hysteresis, nonlinearity, and drift of piezoelectric effects are improved by incorporating the sensors in a feedback control. Experiments demonstrate that the micropositioner is capable of a 10 nm resolution over the travel range of 17.8 mum in the X- and Y-axes and a 0.15 murad resolution over the range of 585 murad in the theta(Z) axis. The crossaxis interferences are within 1.14% of the full range. The results agree well with predictions by theoretical models.

Risk factors for human T-cell lymphotropic virus types I and II (HTLV-I and -II) in blood donors: the Retrovirus Epidemiology Donor Study. NHLBI Retrovirus Epidemiology Donor Study.

In the United States, blood donors have been routinely screened for human T-cell lymphotropic virus (HTLV) since 1988. HTLV-I and -II seropositive blood donors have been identified through confirmatory testing at five participating blood centers and frequency-matched seronegative controls provided information on potential HTLV sociodemographic, parenteral, and sexual risk factors during structured interviews. After adjustment, low educational attainment; accidental needlesticks or cuts; prior blood transfusion; > or = 7 sex partners; and a sex partner from an HTLV-I endemic area were significantly associated with both HTLV-I and -II. Gender did not modify the odds ratios (OR) in the final logistic regression models, despite apparent male-female differences in gender-specific bivariable analysis. Injection drug use (IDU) or having sex with an IDUs were significant risks for HTLV-II, but not for HTLV-I. The OR for donors who had IDU sex partners was 20.6 times higher than those who did not. For IDUs, the OR was increased 10.5 times over nonusers. Abortion was a significant HTLV-II risk factor for women. Our findings indicate that IDU and sex with IDUs are important risk factors for HTLV-II transmission, even among low-risk populations such as blood donors.

Post-renal transplant erythrocytosis.

Erythrocytosis is a relatively common phenomenon following renal transplantation. It is not only associated with some special clinical conditions, but also increases the risk of thromboembolism. We therefore studied the clinical manifestations and possible risk factors of erythrocytosis in our renal-transplant patients. Study of 175 patients showed that erythrocytosis, defined as Hct > or = 50%, was found in 17 patients (9.7%), 14 males and 3 females. Among these 17 patients, 13 received cadaveric grafts and the other 4 living-related grafts. True erythrocytosis, defined as erythrocytosis with elevated red blood cell (RBC) mass, was found in 7 patients. Relative erythrocytosis, defined as erythrocytosis with normal RBC mass, was found in the other 10 patients. Six patients developed acquired renal cysts of the native or graft kidneys during the post transplant period. The incidence of acquired renal cysts in the erythrocytosis group was significantly higher than that in the non-erythrocytosis group. The clinical and demographic characteristics were similar in terms of age, gender, serum albumin, and serum creatinine in the erythrocytosis and non-erythrocytosis groups. The incidences of abnormal liver function, and hypertension were similar between the 2 groups. Seventeen of the 161 patients (10.6%) receiving cyclosporine regimen developed erythrocytosis, but none of the 14 patients receiving non-cyclosporine regimen developed erythrocytosis (p > 0.05). Only one patient with true erythrocytosis had an elevated serum erythropoietin (EPO) level and no thromboembolic complications occurred in the erythrocytosis group. We conclude that: (1) the incidence of erythrocytosis in our transplant patients was 9.7%; (2) a higher incidence of acquired renal cysts was found in the erythrocytosis group; (3) most of the patients with erythrocytosis had a normal serum EPO level; (4) no thromboembolic complications occurred in our patients.