摘要:

We report channel waveguides formed in epitaxialBaTiO3films that were grown on MgO single-crystal substrates using rf magnetron sputtering. In the channel waveguides developed, the lateral confinement of light is achieved via the photoelastic and piezoelectric/electro-optic effects inBaTiO3induced by thin-film stress. Numerical analyses were also carried out on the stress and piezoelectric field distributions in the channel structure, assuming bulk materials properties. The refractive index changes were then calculated taking into account both the photoelastic and electro-optic effects ofBaTiO3.The simulation result suggests that the electro-optic effect (caused by the stress-induced piezoelectric field) accounts for a significant portion (∼10&percent;) of the refractive index change in the channel region. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.122070

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Erbium doping into potassium titanyl phosphate(KTiOPO4or KTP) was performed by pulsed laser deposition. Waveguide laser film in Er-dopedKTiOPO4was formed using bothKTiOPO4and erbium as targets and optically polishedKTiOPO4as a substrate. Rutherford backscattering, photoluminescence spectrometry, x-ray diffraction, and prism coupling method are used to investigate the properties of Er-dopedKTiOPO4.The results show that (1) Er-dopedKTiOPO4emits the characteristic photoluminescence ofEr3+around 1.54 &mgr;m corresponding to transition between the4I13/2and4I15/2manifolds of theEr3+ions inKTiOPO4host. (2) two bright modes in Er-dopedKTiOPO4were observed. This approach may be useful for direct fabrication of thin film waveguide laser for other optoelectrical materials. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.122071

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Lead zirconate titanatePb(ZrxTi1−x)O3(PZT) thin films have been deposited by rf magnetron sputtering on Si substrates from a metallic target of nominal compositionPb1.1(Zr0.4Ti0.6)in a reactive argon/oxygen gas mixture. During plasma deposition,in situoptical emission spectroscopy measurements show clearly a correlation between the evolution of characteristic atomic emission line intensities Zr—386.4 nm, Ti—399.9 nm, Pb—405.8 nm, and O—777.2 nm and the thin-film composition determined by a simultaneous use of Rutherford backscattering spectroscopy and nuclear reaction analysis. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.122072

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The alignment of the highest occupied molecular orbitals (HOMO) at the tris (8-hydroxy quinoline) aluminum(Alq3)/N,N′-di-(3-methylphenyl)-N,N′diphenyl-4,4′-diaminobiphenyl (TPD) heterojunction, used in organic light-emitting diodes (OLED), was determined by growing a TPD layer in several steps on a thickAlq3substrate layer. After each growth step the sample was characterizedin situby x-ray and ultraviolet photoemission spectroscopy. The offset of the HOMO maxima at the interface was determined to be −0.13 eV fromAlq3to TPD. By including the known HOMO–lowest occupied molecular orbital (LUMO) gaps for both molecules into the evaluation, the offset of the LUMO minima was determined to be −0.33 eV fromAlq3to TPD. These values are consistent with previous assumptions that this interface represents a higher barrier for electron injection fromAlq3to TPD than for hole injection from TPD toAlq3.©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.122073

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We report observation of sonoluminescence following irradiation of suspensions of carbon in water with a high power, pulsed laser. The mechanism for generation of a gas bubble is chemical in origin: the heating of the carbon particles by absorption of laser radiation causes the production of high pressureH2and CO through reaction of carbon with the water surrounding the particles. Expansion of the bubble past its equilibrium diameter results in oscillation of the bubble diameter which, several hundred &mgr;s after the initial formation of the bubble, results in emission of optical and acoustic radiation. The effects of laser power, the concentration of carbon in the suspension, dissolved Ar, and temperature on the sonoluminescent intensity are reported. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.122074

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We show that, using the eigenstates of a high-finesse Fabry–Perot cavity, we can measure the small Cotton–Mouton birefringence of gases with a simple tabletop apparatus. It requires only modest magnetic fields(B<1 T)and uses an ultrastable Zerodur high-finesse optical cavity. The method is validated by the measurement of the Cotton–Mouton constant of air and a sensitivity of2.5×10−9 radis obtained for the single pass birefringence. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.122075

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We have investigated light propagation in optical devices by near-field scanning optical microscopy (NSOM) at the telecommunication wavelength of 1.55 &mgr;m. NSOM images obtained on the top of channel waveguides measure the mode profile perpendicular to the propagation direction and show a modulation of intensity along this direction. This modulation demonstrates the periodic variation of the mode size predicted for the propagation in small guides and marks the direction of propagation. We show that NSOM analysis can completely assess complex optical devices with subwavelength resolution: determination of the optical path, variation of the light intensity along this path, and measurement of local radiative losses. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.122076

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The emission spectrum of high quality ZnO epilayers is studied from room temperature up to 550 K. At room temperature and low excitation power a single emission peak is observed which may be identified with the free exciton from its peak energy and dependence on temperature. However, when excitation intensities exceed 400 kW cm−2a sharp peak emerges at lower energy which we attribute to exciton-exciton scattering. At higher excitation intensities (>800 kW cm−2) a second stimulated emission peak emerges at even lower energies: we attribute this peak to be stimulated emission of an electron hole plasma. Similar features are observed for all temperatures up to 550 K. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.122077

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We demonstrate a laser-based adaptive ultrasonic homodyne receiver using dynamic holography in AlGaAs/GaAs photorefractive multiple quantum wells. The dynamic hologram acts as an adaptive beamsplitter that compensates wavefront distortions in the presence of speckle and requires no path-length stabilization. The photorefractive quantum wells have the unique ability to achieve maximum linear homodyne detection regardless of the value of the photorefractive phase shift by tuning the excitonic spectral phase. We achieve a root mean square noise-equivalent surface displacement of6.7×10−7 Å(W/Hz)1/2.©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.122078

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Nominal Ge islands were grown by a molecular beam epitaxy technique on a Si(001) substrate. Island positions and shapes were measured by atomic force microscopy. Two types of islands with different sizes and shapes are present. The Si concentration distribution inside the islands was measured by Raman imaging technique with a 0.4 &mgr;m resolution, and was found to vary between 10&percent; and 30&percent; in large islands and be 10&percent; in smaller islands. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.122079

出版商:AIP    

年代:1998

数据来源: AIP