Volume 92, Issue 6, 15 September 2002
Index of content:
- LASERS, OPTICS, AND OPTOELECTRONICS (PACS 42)
Monomode, nonleaky planar waveguides in a -doped silicate glass produced by silicon ion implantation at low doses92(2002); http://dx.doi.org/10.1063/1.1499204View Description Hide Description
Monomode, nonleaky planar waveguides in a -doped silicate glass were fabricated by 3.0 MeV ion implantation at doses ranging from to at room temperature. The enhancement of the refractive index confined the light propagating in the waveguide without tunneling effects in contrast to the traditional barrier-type waveguide.Annealing at moderate temperatures (about 200 °C) in air was performed, which reduced the propagation loss from 20–30 dB/cm to a minimum of 0.5 dB/cm.
Kinetics and mechanisms of laser-induced decompositions of hydrogenated amorphous carbon films on magnetic hard disks92(2002); http://dx.doi.org/10.1063/1.1500790View Description Hide Description
Laser-induced structural decompositions of hydrogenated amorphouscarbonfilmsdeposited by dc-magnetron sputtering on magnetic hard disks were studied using a microbeam laser (514.5 nm). The laser had varying powers between 3.0 and 0.3 mW at a focused circular spot of 2.5 μm diameter, corresponding to approximate fluence rates between to The effect of laser power on decomposition rate could be expressed by an exponential equation. Based on the relationship between laser power and temperature, relative apparent activation energies for film decompositions were obtained and found to decrease with the increase of film hydrogen content and the elapse time of laser irradiation. All the filmsirradiated with laser powers between 0.75 and 0.3 mW followed the apparent first-order reaction. The reaction order tended to increase at higher laser powers and hydrogen content in the films.
92(2002); http://dx.doi.org/10.1063/1.1481779View Description Hide Description
With plane-wave expansion and the Green function method, the second harmonic generation in a two-dimensional metal photonic band gap(PBG)material is studied theoretically. By appropriately selecting the structural parameters of the PBGmaterial, the wave vectors of the fundamental and the second harmonics can be set at the edges of the PBG. In this case, the second harmonic can be realized efficiently due to metal surface nonlinearity. The discussion can be generalized to three-dimensional systems.
92(2002); http://dx.doi.org/10.1063/1.1499747View Description Hide Description
Near-infrared reflectance spectra of 5 μm thick low-temperature (LT) GaAs films grown by molecular-beam epitaxy at different substrate temperatures on GaAs/AlAs Bragg reflectors (BR’s) have been studied. With decreasing (increasing absorption coefficient of the film), the reflectance of the stop band of the BR decreases monotonously, while the amplitudes of the interference fringes due to the LT-GaAs layer inside the stop band initially increase followed by a decrease for large values. This unusual behavior is explained by a particular optical interference effect of a thick absorbing layer on a strongly reflecting structure. This effect remarkably improves the determination of and enables the detection of As-antisite defects in LT-GaAs films for concentrations as low as where other methods fail.
92(2002); http://dx.doi.org/10.1063/1.1503168View Description Hide Description
This article reports band-edge light emission and detection using silicondiodes. A bulk crystalline siliconlight-emitting diode(LED) demonstrating close to 1% power efficiency at room temperature is combined with a similar diode used as a detector, that collects the light emitted with a high quantum collection efficiency of 33%, to produce a silicon-to-silicon optically coupled system that demonstrates 0.18% coupling quantum efficiency. The siliconLED demonstrates similarly high performance at very low power levels, where it has higher power efficiency than a high efficiency GaAlAs LED.