High-power and high-speed semi-insulating BH structure monolithic electroabsorption modulator/DFB laser light source

By the use of a semi-insulating BH structure the authors have obtained a high-performance monolithic electroabsorption modulator/DFB laser light source having a bandwidth of 10.3 GHz and an output power of 17 mW. The chirp was only 0.1 AA under 10 Gbit/s NRZ modulation.<>     

A radioimmunometric assay for urinary alpha 2-macroglobulin

To measure urinary alpha 2-macroglobulin levels, a sensitive radioimmunometric assay was established. The least detectable level of this assay was 225 pg/ml. A linear correlation between alpha 2-macroglobulin levels and serial dilution of urine samples was found. Western blot analysis and study on column chromatography revealed that the molecular weight of alpha 2-macroglobulin in urine was identical to that of serum alpha 2-macroglobulin. The findings suggested that urinary substance detected by the present assay was truly alpha 2-macroglobulin. Timed overnight urine samples from 49 diabetic patients with retinopathy and 20 healthy controls were measured by the present assay. Patients were classified as Albustix-negative and Albustix-positive patients. The highest urinary alpha 2-macroglobulin excretion rates (alpha 2-MER) was found in Albustix-positive patients followed by Albustix-negative patients and the healthy controls. In view of the fact that the stroke radius of alpha 2-macroglobulin (88A) is larger than that of the restrictive pore (56A), the present finding suggests that leakage of alpha 2-macroglobulin in urine may be induced by defect of non-discriminatory pores in the glomerular basement membrane proposed by Deen and colleagues.     

Extremely low threshold current operation in 1.5-μm MQW-DFBlaser diodes with semi-insulating InP current blocking region

Threshold current operation of 1.5 mA was achieved for 1.5-μm multiple-quantum-well distributed feedback (MQW-DFB) laser diodes (LDs) with semi-insulating current blocking layers entirely grown by metalorganic vapor phase epitaxy (MOVPE). Such low-threshold current is attained by reducing leakage current and mirror loss in the laser structure. The required bias current for achieving several gigahertz bandwidth is markedly reduced due to the enhanced differential gain and low threshold current. Due to the reduced lasing delay time in such low threshold LDs, up to 5-GHz zero-bias current modulation, with a clear eye opening, is successfully demonstrated     

Frequency separation locking and synchronization for FDM opticalsources using widely frequency tunable laser diodes

A laser diode (LD) frequency separation locking method (called the reference pulse method) is proposed. This method has advantageous features for frequency division multiplexing (FDM) networks from the viewpoint of frequency separation stability with a strict frequency separation standard, modulation format independence, controllability over a large number of LDs, and frequency synchronization capability. Frequency locking experiments, using four and ten controlled LDs, confirmed that the control system using the method can stabilize frequency spacing for more than 100 LDs. The frequency fluctuation is suppressed to less than 10 MHz. Frequency synchronization, utilizing the reference pulse method, is proposed and demonstrated experimentally for two controlled LD groups, each consisting of three LDs. Frequency discrepancy between two LD groups was only 2.7% of the frequency separation. Required frequency-swept light power and controlled LD power at the detector input for frequency synchronization indicate that more than 50000 LD groups within a 10 km area, each having 100 LDs, can be synchronized simultaneously     

Preferred orientation and interdiffusion in zinc oxide/copper oxide multilayered films

ZnO/CuO and ZnO/ZnO CuO/CuO multilayered films were deposited on Pyrex substrates at <100° C by ion-beam sputtering. The preferred orientation and interdiffusion of these films were examined for films with varying layer repeat lengths (pari thickness). X-ray diffraction analysis showed a preferred ZnO (002) orientation parallel to the surface in annealed ZnO layers of ≈1 to ≈3 nm thickness; no peak was observed for films with a layer repeat length smaller than 1.1 nm. The degree of preferred orientation reduced with increasing layer thickness in ZnO/CuO films and with increasing ZnO CuO thickness in ZnO/ZnO CuO/CuO films. The decay rate of the low-angle X-ray intensity showed that interdiffusivity is largely dependent on the layer repeat length. A smaller layer repeat length gave a larger value of interdiffusivity.     

Advanced Observations of Lightning Induced Voltage on Power Distribution Lines

Waveforms of induced voltage from lightning strokes to a high stack of the power plant have been measured simultaneously with the current waveforms of lighting stroke to the stack since December 1980. This paper shows the lightning stroke current waveforms and the lightning induced voltage waveforms over a 3 year period from December 1981 through March 1984. The combination of polarities for waveforms of lightning induced voltage and lightning stroke current is indicated below: (1) Seven cases of positive induced voltage in response to negative lightning stroke current were observed. (2) Four cases of negative induced voltage in response to positive lightning stroke current were observed. Distribution of lightning induced voltages along the distribution line length was also demonstrated.