摘要:

A laser cavity closed via the first-order diffracted light of an intracavity acousto-optic modulator is referred to as a frequency-shifted feedback laser laser. It has been proven that the laser output consists of a chirped frequency comb evenly spaced at a cavity-free spectral range. In this letter a phase correlation between the chirped comb components is discussed. A homodyne experiment with a Mach–Zehnder interferometer was carried out to examine the problem. It was clarified that the comb components are highly correlated in phase. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121438

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Emission on theI2(D′→A′),XeI(B2&Sgr;1/2+→X2&Sgr;1/2+)and XeO(2 3&Pgr;→1 3&Pgr;)bands, peaking in the ultraviolet at 342, 253 and 238 nm, respectively, has been generated on a continuous basis in a microdischarge with a static gas fill. Discharges are produced inKr/I2,Xe/I2,orXe/O2gas mixtures by cylindrical devices 400 &mgr;m in diameter and fabricated in silicon. Rare-gas–halide and –oxide microdischarge lamps are attractive ultraviolet or vacuum ultraviolet sources and XeI, in particular, appears to be a potential replacement for Hg resonance line radiation (253.7 nm). ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121439

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A vertical directional coupler fabricated using wafer fusion is demonstrated with a very short coupling length of 62 &mgr;m. The optical propagation loss introduced by the fused layer is investigated. An excess loss of 1.1 dB/cm at 1.55 &mgr;m was measured for waveguides which incorporate a fused junction near the core region. Fused vertical couplers make it possible to realize three-dimensional waveguide structures and compact switching arrays and they solve some of the topology problems of large switch arrays. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121440

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Electrically pumped light emission was observed from a smectic mesophase of liquid-crystalline oxadiazole; 2,5-hexyloxybiphenyl–hexyloxyphenyl–oxadiazole (HOBP-OXD), which exhibits high electron transport capability. The light-emitting diode consisted of the HOBP-OXD film, a copper phthalocyanine vacuum deposited film as a hole injection layer, and a tris-(8-hydroxyquinoline) aluminum vacuum deposited film as an electron injection layer. The emission was linearly polarized originating from highly oriented molecular textures in the smectic mesophase with a degree of orientational order of 0.32. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121441

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We report electroluminescence degradation studies on tris(8-hydroxyquinoline) aluminum(Alq3)-based organic light emitting devices (OLEDs) with Mg:Ag cathodes in ambient conditions. The nonemissive spots in the OLEDs are studied via optical and fluorescence microscopy and via microscopic infrared spectroscopy. Studies reveal that a majority of the nonemissive spots are caused by the growth ofMg(OH)2sites at theAlq3/Mg:Aginterface, associated with local degradation of theAlq3layer. In addition, the growth of elevated cathode bubbles, which also lead to nonemissive spots, is found to be caused by gas evolution from the galvanic corrosion of the Mg/Ag couple as well as from the electrolysis of absorbed moisture. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121442

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We have employed near-field scanning optical microscopy to investigate the influence of specific microstructural defects on the optical properties of thin InGaN/GaN epilayers and quantum wells. These defects are empty “pinholes” with a hexahedron cone morphology that are nucleated by threading dislocations from the GaN buffer layer. By correlating atomic force microscopy with spatially and spectrally resolved photoluminescence (PL) on a 100 nm spatial scale, we find that the pinholes have no clearly observable effect on the PL efficiency, at least partly due to the strong carrier localization in the InGaN nonrandom alloy. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121085

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We report on the demonstration of the femtosecond nonlinear optical response from a two-dimensional monomolecular layer of squarylium dyeJaggregate at 5 °C. The formation of a monomolecular layer Langmuir film was achieved by spreading squarylium dye modified by two propyl and two hexyl groups at the air–water interface, which resulted in a very strongJband(o.d.=0.3)at 777 nm. The transient absorption spectra in a resonant pump-probe measurement showed a low absorption saturation power(9.7×106 W/cm2)and an ultrafast response (300 fs), which are indicative of exciton delocalization over 18 molecules in thisJaggregate, even at 5 °C. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121086

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We propose and demonstrate a method to obtain polarization-insensitive four-wave mixing in a semiconductor optical amplifier. The method makes use of two pumps with orthogonal polarization placed at the two sides of the signal spectrum. Unlike a previously proposed scheme, a large bandwidth of the signal does not set a lower limit to the degree of polarization insensitivity obtained. Using a commercially available pig-tailed semiconductor optical amplifier, we have obtained less than 0.4 dB of intensity variation of the conjugate field for arbitrary changes of the signal polarization. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121087

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Efficient(∼1&percent;)second harmonic generation, resonantly enhanced near&lgr;=8.6 &mgr;m,has been observed in asymmetric double multi-quantum well structures. We used (i) edge-emitting waveguide geometry where the phase matching was achieved by incorporating a separate multiple quantum well region which modifies (via the Kramers–Kronig relation) the dispersion of light and (ii)45°wedge multi-bounce geometry where the phases of second harmonic waves generated at sequential bounces were synchronized by changing the angle of incidence. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121088

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We propose and demonstrate a novel scheme to reduce the recovery time of optical nonlinearity in a semiconductor laser optical amplifier driven under a loss condition for the signal light pulse. Additional light, which is set at a transparency wavelength in the active layer, promotes stimulated recombination of excess carriers induced by the absorption of the signal light. This scheme excludes any additional carrier transport mechanism and nonradiative recombination and hence generation of heat. The principle of operation is experimentally verified by measuring time-domain transmission variance using a pump–probe method. A drastic reduction of the excess-carrier lifetime to less than 70 ps was confirmed. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121089

出版商:AIP    

年代:1998

数据来源: AIP