摘要:

A spatially resolved cathodoluminescence study of ⟨100⟩ dark line defects (DLDs) of degraded II–VI laser diodes based on a ZnCdSe/ZnMgSSe separate confinement heterostructure has been carried out at temperatures between room temperature and 8 K. Cathodoluminescence line scans were used to measure the change of contrasts between the DLDs and the adjacent material. The contrast decreased with decreasing temperature, which suggests that the nonradiative recombination processes associated with DLDs are thermally activated. Activation energies were found to be about 16 and 6 meV for temperatures above and below 200 K, respectively, which may reflect a transition between free carriers and bound excitons at this temperature. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119261

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The value of electro-optic coefficientr33of an electro-optic (EO) polymer film depends on the polarization density achieved after the electric poling process. In this letter, we report a high temperature liquid contact poling method which provides a poling field as high as 250 V/&mgr;m in LD-3 EO polymer film with less surface damages. Ther33value was measured to be 18 pm/V at 633 nm which is 40°/V higher than the previous reported datum. Such a high poling field and therefore largerr33value are not achievable through either contact poling or corona poling. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118333

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

ErbiumLIII-edge x-ray absorption fine structure (XAFS) and4I13/2excited state lifetime measurements were performed on aluminosilicate, fluorosilicate, and phosphate glasses with varying erbium concentration. The local erbium environment is shown to be unique in each host. In the aluminosilicate, erbium is found to have 6.4 nearest oxygen neighbors at a distance of 2.22 Å and with a Debye–Waller factor of 0.031Å2.Erbium in the fluorosilicate glass was found to be more highly coordinated with 7.5 nearest neighbor anions. Erbium in the phosphate glass is found to have a smaller disorder factor of 0.021Å2when compared with the silicate glasses. No variation of the environment (3 shells) is observed with changes in rare earth concentration, while the excited state lifetime varies from 1.0 to 9.8 ms in the aluminosilicates, suggesting the absence of erbium clustering at XAFS detectable distances. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118334

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The crystal structure of cadmium mercury thiocyanate [CdHg(SCN)4] is determined by means of a four circle diffractometer. The structural features and properties of the crystal are described. Blue-violet light output by frequency doubling of a 809 nm GaAlAs laser diode using a cadmium mercury thiocyanate crystal device that is 3 mm thick at the phase matching angle:&thgr;=47.7°,&Jgr;=0°, is realized at room temperature with input power lower than 200 mW. A 404.5 nm light output power of 1.8 mW is also measured for a 576 mW input power of the GaAlAs laser diode. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118335

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Continuous wavelength tuning of 19.1 nm is reported for vertical-cavity surface-emitting lasers. Stress-matched dielectric mirror stacks are added to the micromachined deformable-membrane top mirror to enhance reflectance, resulting in devices with 6.5&percent; quantum efficiency and threshold current as low as 0.34 mA. The laser operates in single mode near 968 nm with 24 dB mode suppression ratio and tuning voltages are below 18 V. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119264

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We have succeeded in fabricating a pseudo one-dimensional photonic band system in the visible region using two facing gratings. The transmittance spectra of 3600 and 1800 grooves/mm grating pairs were measured. The results, along with calculations of one-dimensional photonic bands, show that a photonic band exists and the band edges are near 530 THz. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118206

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We have calculated the threshold current density of the ZnCdSe/ZnSe quantum well laser as a function of temperature by incorporating many body Coulomb interactions, both the heavy- and light hole subbands, as well as the temperature and energy dependencies of linewidth for laser transition. The effect of finite well width and well depth in the Coulomb interaction is also considered instead of taking strictly two-dimensional Coulomb potential. The calculated values of nominal threshold current density are 1.5 times larger than the values calculated without considering Coulomb interaction, whereas calculations using strictly two-dimensional Coulomb potential show 7&percent; overestimation. Good agreement is obtained between the reported experimental results and the theoretical threshold current densities for aZn0.83Cd0.17Se/ZnSemultiple quantum well laser assuming a value of 0.8 for the internal quantum efficiency. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118336

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We report an improved microcavity design which allows the suppression of the viewing angle dependence of the color emitted by a planar device. This is demonstrated for luminescent conjugated polymer based cavities, for which the wavelength change is reduced from ∼60 to 10 nm at an angle of 60°. We introduce the concept of cavity optical length dispersion and suggest structures for which the wavelength change with viewing angle is reduced to 5 nm at a viewing angle of 60° irrespective of the emissive material. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118207

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We demonstrate the generation of continuous-wave terahertz radiation at frequencies up to 3.5 THz by photomixing in LT-GaAs photoconductors with printed dipole antennas. The expected resonance peak was clearly observed in the radiation spectrum of a 50 &mgr;m dipole antenna, and the radiation property was discussed in terms of the antenna impedance. The spectral bandwidth was greater than the electrical bandwidth of the photoconductor determined by the carrier lifetime of the material. The quality of the resonance, however, was not as high as expected because of the imperfect geometry and ohmic loss of the antenna. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118337

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The bulk crystals of 4-aminobenzophenone were grown from organic solution. The refractive indices and nonlinear-optical coefficientsdeffwere measured and were reported. Blue second harmonic emission with wavelength of 433 and 460 nm was observed as pumped by a laser diode, second-harmonic generation and a conversion efficiency of2.5×10−5was obtained at 866 nm. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118208

出版商:AIP    

年代:1997

数据来源: AIP