Search

A novel multiwavelength laser diode based on laser cascade feedback is proposed.

A practical method for extracting microwave backscatter for terrain-cover classification is presented in this paper. The test data are multifrequency (P, L, C bands) polarimetric SAR data acquired by JPL over an agricultural area called 'Flevoland.' The terrain covers include forest, water, bare soil, grass, and eight other types of crops. The radar response of crop types to frequency and polarization states were analyzed for classification based on three configurations: 1) multifrequency and single-polarization images; 2) single-frequency and multipolarization images; and 3) multifrequency and multipolarization images. A recently developed dynamic learning neural network was adopted as the classifier. Results show that using partial information, P-band multipolarization images and multiband hh polarization images, have better classification accuracy, while with a full configuration, namely, multiband and multipolarization, gives the best discrimination capability. The overall accuracy using the proposed method can be as high as 95 % with a total of thirteen cover types classified. Further reduction of the data volume by means of correlation analysis was conducted to single out the minimum data channels required. It was found that this method efficiently reduces the data volume while retaining highly acceptable classification accuracy.

A theoretical model of a codirectional grating-assisted vertical coupler filter-fitted tunable semiconductor laser includes internal-reflection factor at gain-coupler junction. A multimode rate equation analysis, coupled with a composite mode-based coupled-mode formulation, enables the study of weakly and strongly coupled filter structures. The impact of filters and internal reflection on longitudinal mode selectivity are examined.

Ideal modes of coupled waveguides are used to construct an improved coupled-mode formulation which accurately predicts grating period and coupling length. The formulation also accounts for radiation loss due to junctions. The prediction of coupling lengths differs drastically from values provided by waveguide-mode formulation, possibly due to changed field profiles.

Optical guided waves in three-dimensional waveguide structures, caused by a full vector beam propagation method, are simulated. The propagation of transverse electric and magnetic fields are derived, taking into account the polarization dependence and coupling caused by the vectorial nature of the electromagnetic fields. The scalar, semi-vector and full-vector simulations of the rib waveguide are conducted.

The modulation instability of orthogonally polarized optical waves copropagating in highly birefringent optical fibers is studied using a couple-mode technique. Two orthogonally polarized beams with four first-order sidebands were analyzed through a couple-mode formulation in the frequency domain. It was found that modulation instability patterns can be accurately and systematically investigated by application of the technique.

Several experimental analyses are conducted to explain the synthesis, as well as the properties of the series of Ge/Si heterostructures with varying Ge thicknesses. The self-assembly process of the heterostructures is shown to get highly suppressed at the low growth temperatures.