High-power etched-facet lasers

We demonstrate, for the first time, laser diodes with anetched facet fabricated by chemically assisted ion beametching, producing 1?7 W pulsed and 470mW CW output power from one facet. The devices were coated and bonded junction-side-up and tested at room temperature. The single 40 ?m stripe, 300 ?m-long devices exhibit 94 mA threshold current and differential quantum efficiencies of 80% pulsed (78% CW).     

A new synthesis of pyrazolo[1,5-d][1,2,4]triazines from pyrazolecarboxylic acid hydrazides and carbonyl compounds. I

Pyrazolo[1,5-d][1,2,4]triazines were synthesized from pyrazolecarboxylic acid hydrazides and carbonyl compounds. Pyrazolecarboxylic acid N-phenylhydrazide (1c) and formaldehyde gave not only the expected 4hn but 5 , respectively. The methyl substituted hydrazides with acetone afforded hydrazones, pyrazolotriazines or 13 depending on the position of the substituents. The reduction of both products yielded pyrazolecarboxylic acid hydrazides.     

Microwave-assisted direct esterification of a cyclic phosphinic acid with phenols

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Detection of Nepsilon-monomethyllysine using high-performance liquid chromatography and high-performance liquid chromatography-mass spectrometry

Nepsilon-Monomethyllysine was identified in the serum, urine, brain, and liver samples of rats treated per os with L-deprenyl. The identification procedure included reaction with Fmoc chloride, clean-up, and analysis using HPLC-UV-MS. Oral administration of (-)-N-14C-methyl-N-propynyl(2-phenyl-1-methyl)ethylammonium hydrochloride L-deprenyl) to rats resulted in transfer of the radiolabelled methyl group to the Nepsilon-amino group of the endogenous lysine. The radiolabelled Nepsilon-monomethyllysine was urinary eliminated together with the other radiolabelled deprenyl metabolites, such as deprenyl-N-oxide and methamphetamine. The presence of Nepsilon-monomethyllysine has also been traced, and its concentrations were compared in the serum, liver and brain of rats subjected to L-deprenyl treatment. Methyl group transfer from the L-deprenyl to endogenous compounds; and the urinary elimination of their products may offer a vital way to eliminate or to decrease the degree of drug transmethylation to the lysine constituents of blood vessels' proteins.     

High power AlGaAs-GaAs visible diode lasers

A high-power room-temperature AlGaAs graded index separately confined heterostructure (GRINSCH) laser emitting in the visible spectral regime (≃715 nm) is reported for the first time. The device is gain-guided and consists of 12 stripes, each 5 μm in width with a centerline separation of 9 μm. This high-power visible laser has been successfully fabricated using a GaAlAs active layer. The epitaxial layer was grown with significantly lower levels of oxygen compared to those grown using standard metalorganic sources. Threshold currents of 310 mA at 10°C were routinely measured on uncoated devices. The uncoated device had a catastrophic optical damage limit of 540 mW and has a slope efficiency as high as 0.48. No degradation in device performance was observed during a 50-hour 150-mW burn-in     

IR, 1H NMR and 13C NMR spectra of isomeric 1-aryl-4-methyl-3- and-5-pyrazolecarboxylic esters

The IR, ¹H and ¹³C NMR spectra of six esters of 1-aryl-4-methyl-3- and 5-pyrazolecarboxylic acids are reported. On the basis of their spectra the 3- or 5-position of the substituent in such structural isomeric pairs can be established without recourse to the spectrum of the other member of the pair. The spectral data also give information on the conformation, which depends on the relative position and size of the hetero ring substituents.     

Temperature stable heat sink metallisation for improved bonding of c.w. stripe lasers

A heat sink metallisation system for use with indium soldering of semiconductor lasers is presented. The system, consisting of the metals InPtNiCu, is found to be temperature stable during a 1700 h storage test in 120°C. S.I.M.S. inspection detects no deterioration of the indium top layer. Ni is found to be an effective barrier for the Cu atoms in the heat sink and Pt provides good wetting of the indium solder, making the system suitable for large scale bonding procedures.     

High bit rate modulation of narrow-stripe proton-implanted GaAs/GaAlAs injection lasers

High bit rate modulation up to 2 Gbit/s of a narrow -stripe (3 ?m) proton-implanted injection laser using resonance oscillation has been achieved. These results indicate that the narrow-stripe laser has possibilities of high bit rate modulation comparable to the broad-stripe laser. To obtain optimum modulation conditions, pulse height distortion was studied for various bias and pulse currents. Optimum was found for a bias current 5% above threshold and a pulse current of 42 mA in a laser with a threshold current of 111 mA.     

Influence of the floating substrate potential on the characteristics of ESFI MOS transistors

A model is proposed to explain the anomalous current-voltage characteristics of ESFI MOS transistors. Due to the floating state the substrate potential of the ESFI transistor is increasing with increasing majority carrier current flowing through the substrate to source. In the region of multiplication by avalanche that effect will get quite pronounced. The change of substrate potential yields a change of the threshold voltage hereby increasing the drain current and resulting a bend in the I_D(U_D) curves. The assumptions of the model have been justified by additional experiments as with illumination of light or increased temperatures. Based on the physical model a computer program was developed to simulate the I_D(U_D) characteristics of ESFI MOS transistors of the enhancement type, resulting good agreement between measured and simulated characteristics.     

一种GaAs/GaAlAs分别限制单量子阱锁相列阵激光器

本文描述一种由MOCVD生长的GaAs/GaAlAs 分别限制单量子阱片子制作的锁相列阵大功率激光器.由十个单横模器件耦合而成的列阵器件,其阈值电流为67mA,线性输出功率大于500mW,微分量子效率达60％.列阵器件由强耦合区和弱耦合区构成,考察了强耦合区的几何结构对耦合模即输出远场分布的影响.