摘要:

The continuous wave (cw) operation of quantum cascade lasers operating at wavelengths in the 7.4–8.6 &mgr;m range is reported. The GaInAs/AlInAs structures, grown by molecular beam epitaxy, are based on a vertical intersubband transition scheme and use a plasmon‐enhanced waveguide geometry to reduce losses and increase the confinement factor. The single mode cw optical power from one facet is 2 mW up to a maximum temperature of 110 K. In pulsed operation, the highest temperature is 210 K and the threshold shows a weak temperature dependence typical of these class of lasers, with aT0=110 K. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116654

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A simple frequency‐dependent ellipsometric technique for measuring the birefringence, the Pockels and Kerr properties of low glass‐transition temperature photorefractive polymers is proposed. The technique is applied to the characterization of highly efficient DMNPAA:PVK:ECZ:TNF photorefractive polymers and the determination of the microscopic properties of the DMNPAA molecule. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116653

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Dielectric constants of CdTe thin films in the presence of a weak pump beam have been measured at room temperature using photoellipsometric technique in the energy range 1.5–5 eV. An anomalous peak is observed in the dielectric spectra of CdTe thin films deposited in oxygen ambient. The peak height depends on the oxygen content in the film and intensity of the pump beam. No peak was observed when the films were deposited under high vacuum (2×10−6Torr) or if the pump beam power was <25 &mgr;W. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116655

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Second‐harmonic generation of blue light by the nonlinear interaction of two counter‐propagating transverse electric‐polarized fundamental fields in a [112]‐oriented (Al,Ga)As/GaAs antiresonant waveguide is demonstrated. Theoretical calculations of the visible output power for given fundamental inputs are shown to agree with experiment. Our results show that GaAs‐based materials may offer another alternative for the development of blue/green light‐emitters. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116656

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Dielectric apertures, formed by oxidation or wet‐etching of high Al content AlGaAs layers in vertical cavity lasers, have recently been used for improved device performance. In this letter an iterative numerical analysis is used to estimate the excess optical losses as the device diameter is reduced. For smaller sizes, where single‐mode devices are possible, the optical scattering losses become significant unless the aperture is tapered to approximate a perfect lens or is thin to approximate a weaker waveguide. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116657

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Quasi‐phase‐matched (QPM) second harmonic generation in a poled polymer waveguide has been realized. A waveguide with a periodic structure was fabricated by conventional photolithography and reactive ion etching. The waveguide with a QPM structure was composed of poled polymer and UV cured epoxy resin. Phase‐matched second harmonic generation was observed, using laser light with a fundamental wavelength 1.48–1.65 &mgr;m. This phase matched condition was dependent on the periodic length. The waveguide had a typical second harmonic generation efficiency of about 4×10−1% W−1 cm−2around a wavelength of 1.55 &mgr;m. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116658

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We show that incoherently coupled soliton pairs are possible in biased photorefractive crystals, under steady‐state conditions. These solitons can propagate in bright‐bright, dark‐dark, as well as in bright‐dark configurations. Such soliton pairs can be established provided that the carrier beams share the same polarization, wavelength, and are mutually incoherent. Relevant examples are provided where the photorefractive crystal is of the strontium barium niobate type. The characteristics and stability properties of these soliton states are also discussed in detail. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116659

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The 80 kJ electrothermal gun facility at Kumamoto University was assembled in order to investigate the phenomena of capillary discharges and to determine parameters of plasmas produced by a high power pulse discharge in the capillary. The behavior of capillary discharges is observed by using an image converter camera in order to make clear the early phenomena of the capillary discharge in different ambient pressures. The behavior of early capillary discharges varies from arc discharge to surface discharges with decreasing ambient pressure. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116660

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Fullerite surface modifications induced by 1064 and 266 nm pulsed laser irradiation have been studied by scanning electron microscopy. The formation of micropatterns with a well‐defined periodicity is reported. The morphology of the periodic nanostructures can be controlled by varying the laser fluence, the angle of incidence, and the wavelength. The different patterns observed for infrared and ultraviolet irradiation suggest that electronic and thermal effects are responsible of the formation of the periodic structures. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116661

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We report nanometer‐sized silicon (Si) crystallites prepared by excimer laser ablation in constant pressure inert gas ambient. Size distribution of the Si ultrafine particles depends on the pressure of inert gas ambients. The relation between the average size and the ambient pressure can be explained by an inertia fluid model. It is verified that the size of the Si ultrafine particles is ∼3 nm and greater in diameter. Furthermore, crystallinity of the nanoscale ultrafine particles is crystalline similar to that of bulk Si. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116662

出版商:AIP    

年代:1996

数据来源: AIP