Volume 99, Issue 7, 01 April 2006
Index of content:
- LASERS, OPTICS, AND OPTOELECTRONICS
99(2006); http://dx.doi.org/10.1063/1.2181310View Description Hide Description
The excess optical attenuation at wavelengths around induced by subamorphous dose ion implantation of silicon-on-insulator rib waveguides has been quantified. Optical attenuation is related to the introduction of lattice defects such as the silicon divacancy. After implantation at a dose of , the attenuation is greater than . Using positron annihilation spectroscopy to determine the vacancy-type defect concentration, it is demonstrated that the absorption component of the excess attenuation can be predicted using a simple analytical expression. Additional losses are suggested to result from a defect induced change in the real part of the refractive index of the siliconwaveguide. A processing strategy for ensuring that the absorption component dominates the excess attenuation is described, and it is shown that selective implantation of a relatively low dose of inert ions is an efficient method for the reduction of optical cross talk in silicon photonic circuits.
99(2006); http://dx.doi.org/10.1063/1.2183407View Description Hide Description
The photoluminescence yield of undoped semiconductors strongly depends on the excitation power and the intensity distribution. The literature does not address this problem in spite of the fact that quoted recombination lifetimes vary at least over an order of magnitude. A simple cylindrical model based on nonlinear recombination and ambipolar carrier diffusion serves to simulate the photoluminescence yield. The radiative and Auger recombination are responsible for the nonlinearity. Using the controlled Gaussian beam distribution of a He–Ne laser to excite the photoluminescence, we experimentally test the predictions of the calculations on a thin GaAs layer embedded in . These observations demonstrate that the concept of a universal lifetime is not valid for undoped materials having residual impurity concentrations well below . The lifetime concept also looses its physical significance in strongly pumped materials, where the injected carrier densities are comparable or larger than the background doping.
Enhancement of the diffusion of oxygen and boron in silicon crystals under irradiation of infrared laser light99(2006); http://dx.doi.org/10.1063/1.2189022View Description Hide Description
Numerical and experimental analyses revealed the enhancement of diffusion of oxygen and boron by laser irradiation. We studied the effect of laser irradiation on the enhancement of diffusion of boron and oxygen including both isotopes of and . The study clarified that the diffusion of the impurities was enhanced by laser irradiation by about 2.5–8 times more than that in the case without laser irradiation in the temperature range from . We confirmed from temperature measurements of the samples that such enhancement was not based on temperature increase caused by laser irradiation but was based on the effect of irradiation of the laser. The effect of frequency of the laser on the diffusion was observed by changing the wavelength of the laser.
99(2006); http://dx.doi.org/10.1063/1.2190072View Description Hide Description
A theoretical model for single-defect one-dimensional magnetic photonic crystals with combined linear and circular birefringences is presented. The model elucidates the polarization response of waveguide magnetophotonic crystals and predicts a spectrally asymmetric transmittance detuning from the Bragg frequency. The key components of the model are (a) the presence of two orthogonal elliptically polarized normal modes propagating at different speeds and (b) resonant transmission of these modes through the photonic crystal. Analytical expressions for the normal mode vector field amplitudes and their transmittance through the photonic crystal are obtained. The model predicts a significant nonreciprocal rotation in the presence of linear birefringence levels that would normally suppress the Faraday rotation in ordinary optical channels. Agreement is found with transfer matrix simulation predictions.