摘要:

From external electric field dependence of photocurrent spectra of a quantum wellp‐i‐nphotodiode connected to a series resistive load, it is predicted and directly demonstrated that photocurrent bistability is obtained with respect to the variation of the external bias voltage when the device is illuminated by an incident ray in a certain wavelength region. Furthermore, additional self‐consistent interpretation is given with empirical data taken for the system with no series resistor.

ISSN:0003-6951    

DOI:10.1063/1.101782

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The hologram fixing process in a Bi12SiO20crystal arises due to the formation of a complementary grating of positive charges localized in shallow traps. Uniform illumination of the crystal with blue or green light erases the electronic charge pattern but leaves the positive charge grating undisturbed. Due to the smaller mobility lifetime product of holes, this grating decays at room temperature with a time constant that is much longer than that of the electronic grating. We show in this letter that the readout time constant can be further increased considerably by cooling the crystal. Images retrieved from a crystal kept at 0 °C temperature and under continuous illumination for a few hours are presented. The energy levels of the hole trapping sites involved in this process are found to be situated at 0.56 and 1.1 eV above the valence band.

ISSN:0003-6951    

DOI:10.1063/1.102441

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Several combinations of incident polarization and detection schemes suitable for direct detection of transitions in magneto‐optical disk systems are described. One such combination uses a circularly polarized light with a single split detector in the far field. Another scheme uses linear polarization in conjunction with differential detection. In the first scheme the medium must be optimized for Kerr rotation while the second method requires maximum ellipticity.

ISSN:0003-6951    

DOI:10.1063/1.101783

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

For wavelengths near the quantum well absorption edge it is found that fewer quantum wells favor ideal phase modulation in GaAs/AlGaAs waveguide modulators. This is due to the dominance of the linear electro‐optic effect over quantum absorption effects in the separate confinement waveguide. For TE polarization, it is found that the chirp parameter varies from <1 to >10 at −5 V and &lgr;=0.89 &mgr;m in actual devices depending on the number of wells. The data fit estimates from theory. For TM polarization no dependence was observed as expected. For an integrated laser/phase modulator (with different absorption edges) a 4‐well structure may be near optimum to maximize the modulation efficiency and to still have low laser threshold current.

ISSN:0003-6951    

DOI:10.1063/1.101784

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We report the first successful operation of a diode pumped continuous‐wave (cw) thulium‐doped fluorozirconate fiber laser at 2.3 &mgr;m. Output power of 1 mW and slope efficiency of 10% are demonstrated. Saturation effects limiting efficiency are observed and discussed.

ISSN:0003-6951    

DOI:10.1063/1.101785

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A significant improvement in the maximum output power of a 1.3 &mgr;m GaInAsP/InP laser with a semi‐insulating current confinement structure is reported. The improvement has been achieved by interposing ann‐type InP layer between ap‐InP substrate and an Fe‐doped InP layer. A maximum cw output power of 180 mW and a modulation bandwidth of 8.5 GHz have been obtained.

ISSN:0003-6951    

DOI:10.1063/1.101786

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A new technique for increasing the laser penetration efficiency of metals has been developed. By amplitude modulating a free‐running neodymium:yttrium aluminum garnet laser pulse, the depth of the crater was increased and the threshold energy for reliable hole drilling was decreased significantly. It was observed that the effect of chopping was optimal at 8–12 kHz with a 70% duty cycle. We believe that this improvement is due to an increase in the vapor recoil pressure and reduced plasma screening. Possible acoustic resonance effects have also been considered and will be discussed.

ISSN:0003-6951    

DOI:10.1063/1.101787

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The high‐speed performance of InGaAs interdigitated metal‐semiconductor‐metal (M‐S‐M) photodetectors illuminated with 1.55 and 1.3 &mgr;m wavelength radiation is modeled using a two‐dimensional transit time calculation. Excellent agreement is found with the experimental pulse response of detectors with interdigital spacings of 2 and 3 &mgr;m. We study the dependence of the bandwidth on the device dimensions, and also examine the quantum efficiency. The results should aid the design of InGaAs M‐S‐M detectors with the optimum combination of bandwidth and efficiency for a given application.

ISSN:0003-6951    

DOI:10.1063/1.101788

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Using the technique of anodization spectroscopy we have shown that it is possible to directly observe individual atomic planes in high quality Nb/Ta epitaxial multilayers. The signal corresponding to the atomic planes is superimposed on the superlattice structure associated with the different anodization rates of the two metals. The results imply that an upper limit of less than 0.1 nm can be placed on the fundamental resolution of this novel measurement technique. As a test of this measurement we have obtained data from films grown on different orientation substrates, and have shown that the separation of the peaks corresponds to the known lattice spacings in the growth direction. The mechanisms responsible for the very uniform propagation of the anodization front and the consequent ability to observe directly the atomic planes normal to the exposed surface are discussed.

ISSN:0003-6951    

DOI:10.1063/1.101789

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Disordering of ZnSe/ZnS strained‐layer superlattices(SLSs) induced by Si ion implantation and subsequent low‐temperature thermal annealing was confirmed. Si ions were implanted (100 keV, 1×1016ions/cm2) into SLSs (140 A˚ ZnSe‐140 A˚ ZnS, ten periods). By secondary‐ion mass spectrometry analyses, periodic profiles of Se and S were clearly observed just after the ion implantation; however, they disappeared after subsequent thermal annealing (450 °C, 3 h). Photoluminescence measurements showed the peak of ZnSxSe1−xalloyed crystal after thermal annealing. The disordering is mainly induced by the diffusion of defects generated by the ion implantation at the early stage of low‐temperature thermal annealing. This low temperature and planar process will be very useful to the fabrication of II‐VI compound semiconductor optical and electrical devices.

ISSN:0003-6951    

DOI:10.1063/1.101790

出版商:AIP    

年代:1989

数据来源: AIP