摘要:

Oxygenated polymeric fullerene films synthesized in argon plasma show strong photoluminescence in near-infrared and visible region (1.50–2.36 eV) at room temperature excited by a 514.5 nm argon ion laser. After being annealed at different high temperatures, photoluminescence decreased in intensity. The generation and decrease of the photoluminescence were explained in terms of the change of the fullerene C60symmetry. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118983

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A photoconductive sampling technique was developed that is well suited to probing cryogenic devices such as mesoscopic devices. Low-temperature-grown GaAs photoconductive switches were embedded in a coplanar waveguide and illuminated with pigtailed optical fibers. The chip was conduction cooled in a liquid helium cryostat. The fiber-coupled switches were designed to minimize external infrared-radiation loading and to obtain efficient optical to electrical conversion. Measurements at 300, 77, and 4.2 K demonstrate very low thermal loading and a temporal resolution of 4.7 ps—arising from dispersion of the femtosecond pulses(&lgr;=810nm)in the optical fiber. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119011

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Photon tunneling of lasing emission from a dye-doped microspherical particle to an object was investigated by use of a microspectroscopy system combined with a laser manipulation technique. An emission spectrum drastically changed with approaching the lasing microsphere to a glass plate. The intensity ratio between resonant peaks exhibited exponential dependence on the sphere-object distance, whose decay constant agreed with the penetration depth of an evanescent field just outside of the microsphere. The variation in the spectral profile can be explained with the Mie scattering theory. Applicability of the lasing microsphere as a probe of a near-field scanning optical microscope is discussed. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118984

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We have demonstrated stable and efficient 80 W cwTEM00operation(M2=1.1)of a diode-side-pumped Nd:YAG rod laser. The laser has a simple and scalable configuration consisting of a diffusive pumping reflector and a polarization-dependent bifocusing compensation. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118985

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The effect of carrier diffusion on threshold current is studied quantitatively for the oxide-aperturbed 780 nm vertical-cavity surface-emitting lasers (VCSEL) from the measured spontaneous emission. The oxide aperture size of 2–10 &mgr;m is prepared and characterized. The diffusion coefficient of4.6 cm2/sand the nonradiative recombination coefficient of6.8×107/sare obtained using the independence of the nonradiative recombination coefficient on the laser aperture size. The contribution of carrier diffusion loss is 42&percent; of the threshold current for the 2 &mgr;m VCSEL. The relative contribution of the diffusion becomes smaller for the larger devices as is expected. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118986

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We experimentally demonstrate surface-emitting second harmonic generation in a waveguide containing asymmetric coupled GaAs/AlGaAs quantum wells. The nonlinear conversion efficiency is enhanced by reversing the asymmetric well orientation every coherence length, in order to quasiphase match the vertical second harmonic generation process. The measured spectrum of the asymmetric quantum well susceptibility is dominated by an excitonic peak at a pump frequency corresponding to half of the first electron-heavy hole transition energy. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118987

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Bringing an elastomeric phase mask into conformal contact with a layer of photoresist makes it possible to perform photolithography in the near field of the mask. This technique provides an especially simple method for forming features with sizes of 90–100 nm in photoresist: straight lines, curved lines, and posts, on both curved and planar surfaces. It combines experimental convenience, new optical characteristics, and applicability to nonplanar substrates into a new approach to fabrication. Nanowire polarizers for visible light illustrate one application for this technique. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118988

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The polarizations and frequencies of the two eigenstates of a vertical cavity surface emitting laser with an external cavity containing a quarter-wave plate are theoretically and experimentally analyzed. It is shown that the polarizations of these eigenstates are fixed by the neutral axes of the quarter-wave plate. The optical pulses at a frequency equal to a half of the free spectral range of the external cavity, observed through a linear polarizer, are due to beats between the two eigenstates. All these features show that such polarization self-modulated lasers oscillate in a single round trip. ©1997 American Institute of Physics. 

ISSN:0003-6951    

DOI:10.1063/1.118982

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We report white light emission from InGaN/conjugated polymer hybrid light-emitting diodes (LEDs). White light sources (or sources with various colors) are achieved by combining the photoluminescence (PL) from semiconducting (conjugated) polymers with the emission from high efficiency InGaN based LEDs; the InGaN based LED provides the blue component and, simultaneously, serves as the short wavelength pump source for exciting the PL of the polymer film(s). ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118989

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Constant-height scanning is demonstrated to improve near-field microscopy by eliminating artifacts connected with topography scanning, hence, to image the inherent electromagnetic contrast. Microwaves are chosen for this study because the long wavelength eliminates coherence artifacts, owing to a scale separation of wave and image frequencies. Measured amplitude and phase images of conductive films are quantitatively analyzed by considering the longitudinal electric near field. The observed spatial resolution of 200 nm equals the probing tip size and proves that the skin depth &dgr; of the tip material (here, 1600 nm) presents no resolution limit to scanning optical microscopy. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119255

出版商:AIP    

年代:1997

数据来源: AIP