摘要:

Freely propagating THz pulses are detected in electro-optic (eo) crystals by monitoring the phase retardation (PR) of an infrared femtosecond probe pulse. This technique permits the determination of the temporal shape of the THz pulse in the subpicosecond time domain. We present measurements inLiTaO3,LiNbO3, and ZnTe and compare their signal performance as eo crystals with theoretical calculations for the PR signal. ZnTe shows the best performance for eo detection. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119093

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Hydrides on the6H-SiC(0001¯)and (0001) surfaces before and after hydrogen annealing were investigated by infrared attenuated total reflection spectroscopy. The absorption bands ofCH2andCH3were observed from the6H-SiC(0001¯)and (0001) surfaces before hydrogen annealing. After hydrogen annealing, a sharp C–H stretching vibration attributable to a monohydride appeared on the6H-SiC(0001¯)surface, in contrast to a sharp Si–H stretching vibration which can be observed on the6H-SiC(0001)surface. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119094

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The ability of a laser magnetometer to measure the natural remanent magnetization of rocks is experimentally investigated. It is shown that the performance of such a magnetometer permits the rapid measurement of rock magnetizations of less than1 A m−1in a laboratory without the need of any magnetic shielding or cryogenic facilities. Moreover, the laser magnetometer is experimentally shown to be able to measure the distribution of magnetization in spatially inhomogeneous samples. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119095

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We demonstrate that quasi-phase-matched second harmonic generation occurs in annealed proton-exchanged (APE)X-cut MgO 5 mol &percent; dopedLiNbO3(MgO:LN) waveguides supporting a TE-mode guided wave. Formation of a domain inversion was achieved by applying electric fields inX-cut andY-cut MgO:LN. The depth of the formed domain inversion was 1 &mgr;m with a period of 4.75 &mgr;m. Anomalous characteristics of current versus voltage(I–V)of samples having domain inversion formed therein were found to have similar properties to a diode. A blue light having a wavelength of 475 nm and a power of 2.2 mW has been obtained with a normalized second harmonic conversion efficiency of60&percent;/W cm2with uniform grating of 6 mm by using aTi:Al2O3laser as a fundamental wave source. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119096

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We present detailed images of the Rb polarization in a high-pressure optical pumping cell. Images taken at high magnetic field strengths (≈37 G) yield precise information on the relative occupation probability of the hyperfine Zeeman sublevels. Low-field (⩽4 G) images yield very high resolution (less than 1 mm) maps of the spatial distribution of the Rb polarization. For optical pumping in the presence of high-pressure buffer gases, the measured populations of the hyperfine magnetic sublevels are shown to be well described by a spin temperature, even though the Rb–Rb spin exchange rate is much smaller than the rates of optical pumping or electron-randomizing Rb–Xe collisions in the buffer gas. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119097

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Avalanche upconversion is reported forEr3+doped fluoroindate glass pumped at 633.5 nm. Strong frequency upconversion signals and intensity dependent transmittances are observed. The results of the transient and steady-state measurements agree well with the predictions of a rate-equation model which take into account cross-relaxation processes among pairs of erbium ions. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119098

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We report on sound-echo experiments at 70 and 150 GHz using a 3-mm-thick type IIa diamond with a (100) cut. Longitudinal sound was piezoelectrically excited and detected by means of a sputtered ZnO film. The method of linear frequency modulation of a continuous wave was applied. The temperature dependence of sound attenuation could be measured at 70 GHz up to a temperature of 200 K where an attenuation of about 1 dB/mm was observed. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119099

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

As in other plasma devices with a curved magnetic field geometry, an asymmetric density profile is observed in the PLADEPUS, a toroidal plasma source, at the University of Sydney. In this letter, we demonstrate that the asymmetric density profile can be improved by means of a positive bias electric field at the edge of the plasma. With the bias field, the density profile becomes symmetric and broadened, and the plasma density is enhanced. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119100

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

An experimental investigation of the effect of magnetic field on the breakdown voltage characteristics of a multigap pseudospark device, with hydrogen gas, in a hollow anode–cathode, as well as a hollow cathode–anode configuration, is presented. The breakdown pressure at a particular discharge voltage increases with the increase in the applied axial magnetic field, and the magnitude of the increase is more pronounced at lower discharge voltages causing a right shift to the characteristic discharge curve in both the configurations. Application of a transverse magnetic field also resulted in a shift of the characteristic discharge curve towards the right. The observed results are compared and discussed with that found for parallel electrode geometry. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119101

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Large-scale integrated fabrication in a H2containing atmosphere, for example, during the passivation process, can cause serious damage inmetal/Pb(Zr,Ti)O3/metal capacitors (i.e., Pt/PZT/Pt capacitors). To reveal the cause of theH2damage, we investigated the behavior of hysteresis curves and the leakage current of capacitors with a top electrode of Pt, Pd, Au, or Ag. Capacitors with a top electrode of Au or Ag are more resistant to theH2annealing damage than those of Pt or Pd. We found that theH2damage was strongly affected by the catalytic activity and adsorptive properties of the top electrode when exposed toH2. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119102

出版商:AIP    

年代:1997

数据来源: AIP