摘要:

Use of a thin step etched optical fiber probe in a scanning near-field optical/atomic-force microscope (SNOM/AFM) produced frictional imaging. The probe was fabricated by the etching of an optical fiber to decrease its diameter and sharpen the tip end with a HF solution and by irradiating aCO2laser beam to bend the tip. The spring constant of the thin probe is 100 times smaller than that of a conventional optical fiber probe, which allows the probe to be used as a contact AFM mode and in frictional imaging. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120446

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We present a novel organic crystal, 5-(methylthio)-thiophenecarboxaldehyde-4-nitrophenylhydrazone, with a large effective phase-matchable nonlinear optical coefficient,deff=29±3 pm/V at &lgr;=1318 nm. Single crystals of dimensions up to 25×5×5mm3were grown. The large off-diagonal nonlinear optical coefficients can be explained with the two-dimensional geometry of the chromophores in the crystal lattice. Our crystal is ideally suited for optic parametric oscillation in the wavelength range from 1000 to 2500 nm. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119343

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Photoluminescence (PL) measurements were performed on cubic GaN films grown on GaAs(100) substrates by metalorganic vapor phase epitaxy. The cubic GaN films show a high optical quality that enables us to study the PL spectra in detail. From temperature and excitation intensity dependence, the emission lines at 3.274 and at 3.178 eV were assigned to the excitonic transition and the donor–acceptor pair transition, respectively. We also observed two additional emission lines at 3.088 and 3.056 eV. An excitonic emission at 3.216 eV with full width half maximum value as small as 73 meV was observed at 300 K. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119344

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Third-order nonlinear optical susceptibilities&khgr;(3)oftrans-dihydroxy-1,6,11,16-tetra-(tert.butyl) porphyrazine germanium[t-Bu4PazGe(OH)2]thin films measured by the third-harmonic generation technique are reported for the first time. The&khgr;(3)(−3&ohgr;;&ohgr;,&ohgr;,&ohgr;)value as high as1.3×10−11esu was observed from a dominant three-photon resonance. The&khgr;(3)values of porphyrazine germanium derivative are analogous to metallophthalocyanines and these results imply that axial substitution is beneficial for enhancing third-order optical nonlinearity. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119386

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Triplet state nonlinearity ofC60in toluene is studied using theZ-scan technique with 8 ns, 532 nm pulses from aQ-switched Nd:YAG laser. Compared with theZ-scan results ofC60in toluene and iodine in toluene with proper concentration, the solvent instantaneous nonlinearity and the thermal nonlinearity resulting from theC60intersystem crossing and excited state absorption are estimated. The real part of theC60triplet state molecular polarizability is obtained. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119345

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We present new designs of more efficient terahertz (THz) radiation emitters and detectors enhanced by electric field singularities using sharp and laterally offset electrodes. We compare the performances of the terahertz emission and different polarization properties resulting from these structures. An average THz radiation power of 3 &mgr;W is achieved under 20 mW excitation, calibrated by free space electro-optic sampling. We also study the gap size dependence of the THz radiation, and find an absence of a positive electrode effect in the small gap limit. ©1997 American Institute of Physics. 

ISSN:0003-6951    

DOI:10.1063/1.119346

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We report far-infrared absorption in directly doped self-organized InAs quantum dots. Photoluminescence spectra demonstrate a blue shift in peak intensity for increasing doping in the quantum dots. Far-infrared absorption measurements using a Fourier transform infrared spectrometer show absorption in the range of 13–18 &mgr;m for quantum dots withAl0.15Ga0.85Asand GaAs as the barrier material. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119347

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Scanning microdeformation microscopy is a kind of ac contact force microscopy sensitive to the variations of the local elastic constants of the investigated material. In this letter a new optical interferometer designed for detecting the small displacement of the cantilever is reported. The setup is described and some applications of the laser probe to scanning microdeformation microscopy are demonstrated. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119348

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Optical manipulation of disclinations and defects in liquid crystal films was demonstrated and discussed in terms of mass transfer induced by radiation pressure and of molecular rotation under the optical electric field. Orientation of liquid crystal molecules was controlled by changing the polarization direction of a focused cw laser beam. A disclination line could be deformed by moving the focal spot, just like drawing a bow. A point defect followed the laser beam so that it could be freely transported in the film. When two disclination points were optically manipulated to become fused, the defects disappeared immediately and did not return after switching off the laser. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119349

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A direct mark edge detection scheme for readout in phase-change optical disk systems is described. The medium for edge detetection must be optimized to have a 90° phase difference between the amorphous mark and the crystalline space. Theoretical analysis and numerical simulation have shown that the readout signal using mark edge detection is as good as that using conventional detection of reflectivity for long marks and superior for short marks. Noise level at the output of differential edge detection is lower than that at the output of conventional detection. We also show experimental results that confirm these predictions. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119350

出版商:AIP    

年代:1997

数据来源: AIP