摘要:

A gallium complex(GaMq2Cl)consisting of two 2-methyl-8-hydroxyquinolines (Mq) and a chlorine was synthesized and used for the fabrication of organic light-emitting diodes (OLEDs). The photoluminescent peak ofGaMq2Clat 492 nm was as strong in intensity as that of tris(8-hydroxyquinolinato)aluminum(Alq3).The OLED usingGaMq2Clas an emitting material showed blue-green luminance of10 490 cd/m2. When it was used as an electron transport material in a rubrene doped cell, an OLED with a high luminance of27 700 cd/m2was obtained. We found thatGaMq2Clalso was useful as a host material. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121448

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Orientational photorefractive Bragg diffraction is observed in high- and low-molar-mass liquid crystal mixtures doped with fullerene(C60).These novel materials are in a nematic phase without phase separating. In the functionalized materials, we observe a high two-beam coupling gain coefficient(&Ggr;=75 cm−1)with a low applied field of 4 V/&mgr;m, low total losses (32 cm−1including scattering, reflection, and absorption), a high diffraction efficiency (9&percent;), and response time of 200 ms. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121230

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Using a linearly chirped optical probe pulse in free-space electro-optic measurements, a temporal wave form of a co-propagating THz field is linearly encoded onto the frequency spectrum of the optical probe pulse, and then decoded by dispersing the probe beam from a grating to a detector array. We achieve acquisition of picosecond THz field pulses without using mechanical time-delay device. We also demonstrate asingle-shotelectro-optic measurement of the temporal wave form of a THz pulse. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121231

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

In laser purification of Ag from an Ag-In alloy based on multistep photoexcitation for ionization, we demonstrated that a time-division collection method employing a high-speed rotation disk is effective in suppressing an impurity level. High purity Ag film of 0.11&percent; In impurity concentration was obtained from a starting Ag-In alloy of 6.08&percent; In. This impurity reduction was much higher than the case without the new method, in which only half reduction was obtained. This work also showed that the contamination is mainly due to neutral atoms that failed to be irradiated by pulsed-mode lasers. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121232

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

This letter describes a thermally-actuated reflection mode asymmetric Fabry–Perot modulator that consists of a thin transparent elastomeric film bounded by partially and highly reflecting metallic mirrors. The thickness of the transparent layer determines the intensity of light reflected from the modulator; changes in its thickness modulate the reflectivity. Electrical current flowing through the highly reflecting mirror provides a source of heat for controlling, by thermal expansion, the thickness of the elastomeric film. Modulators with this design show contrast ratios>15 dBand insertion losses<0.3 dB.©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121233

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Electrical single- and dual-wavelength tuning and three-wavelength operation of an actively mode-locked fiber ring laser generating picosecond pulses were demonstrated by using a cavity with large dispersion. A continuous tuning range up to ∼37 nm of single-wavelength picosecond pulses at ∼1 GHz was achieved by only changing the modulation frequency. Continuous wavelength tuning of dual-wavelength (18.5 nm spacing) 3 GHz picosecond pulses was also demonstrated with a tuning range up to ∼17 nm. The tuning ranges were mainly limited by the gain bandwidth of the Er-doped fiber. Simultaneous generation of three-wavelength picosecond pulses at ∼2 GHz was also demonstrated by further increasing the cavity dispersion. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121263

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Spontaneous emission from dye molecules embedded in periodic dielectric structures was investigated. The structures consist of close-packed arrays of dye-doped polystyrene microspheres. Periodic arrays of polystyrene spheres with a submicrometer diameter were shown to provide a nonoverlapping gap or pseudogap in the visible spectral region. The modification of the spontaneous emission from inside the pseudogap structure was observed as a deep dip in the photoluminescence spectra. The alteration in the emission spectra is explained in terms of the partial suppression of radiation modes due to the periodic dielectric structures. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121234

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Self-focusing by thermal heating because of absorption of a guided light beam in a planar strontium–barium–niobate waveguide is of interest for all-optical data processing. When a guided probe beam intersects the pump beam under a small angle inside the waveguide, the self-focusing effect in conjunction with self-bending because of the photorefractive effect can be used for large angle deflection of the probe beam and for switching with time constants of fractions of milliseconds. Deflection angles of the outcoupled probe light up to 0.23 rad in air and frequencies up to 3 kHz for optical switching are reached in the experiment. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121317

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

In laser ultrasonics a laser is used to excite ultrasonic waves. The intensity profile of the laser on the sample can be used to control the frequency of the ultrasound generated. In this letter we show how the frequency content of Rayleigh (surface acoustic) waves generated with an 82 MHz mode-locked laser can be controlled using computer generated holograms (CGHs). To demonstrate the effectiveness of the frequency control the CGHs used weredefocusedto generate new illumination profiles. The agreement between the actual and predicted amplitudes for these profiles is striking. Using this technique, the intensity output from the CGHs may be considered as a tunable Rayleigh wave source. ©1998 American Institute of Physics. 

ISSN:0003-6951    

DOI:10.1063/1.121235

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Boron nitride nanotubes (BN-NTs) were synthesized by using excimer laser ablation at 1200 °C in different carrier gases. The main characteristic of the BN-NTs produced by this method is that nanotubes are of only one to three atomic layers thick, which could be attributed to the dominance of the axial growth rate over the radial growth rate. The diameter of the BN-NTs ranged from 1.5 to 8 nm. The tips of the BN-NTs are either a flat cap or of polygonal termination, in contrast to the conical ends of carbon nanotubes. The atomic ratio of boron to nitrogen as measured by means of parallel electron energy loss spectroscopy is 0.8, which is within the experimental error of the stoichiometry of hexagonal BN structure. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121236

出版商:AIP    

年代:1998

数据来源: AIP