Reduced linewidth re-broadening by suppressing longitudinal spatial hole burning in high-power 1.55-/spl mu/m continuous-wave distributed-feedback (CW-DFB) laser diodes

For the first time, the impact of longitudinal photon density distribution and longitudinal carrier density distribution on the spectral linewidth re-broadening effect in single-electrode 1.55-/spl mu/m distributed feedback (DFB) laser diodes (LDs) is investigated experimentally in details. By optimizing the front-to-rear facet power ratio, the nonuniformity of the photon density distribution along the laser cavity is reduced, hence reducing the degree of longitudinal spatial hole burning (SHB). Using this optimized value of front-to-rear facet power ratio, the degree of longitudinal SHB can be further reduced through reduction of the nonuniformity of the longitudinal carrier density distribution by increasing the cavity length. As a result, the local stimulated emission is reduced, hence reducing linewidth re-broadening caused by longitudinal SHB. The outcomes of this analysis is being used fruitfully to design high-power 1.55-/spl mu/m DFB LDs exhibiting very narrow spectral linewidth of approximately 1.3 MHz at an output power of 175 mW under continuous-wave operation.     

Combination of AFM with an objective-type total internal reflection fluorescence microscope (TIRFM) for nanomanipulation of single cells

A new instrument was constructed by combining an objective-type total internal reflection fluorescence microscope with an atomic force microscope (AFM). Our purpose of constructing such an instrument is to detect and confirm the result of cellular level manipulations made with the AFM part through the detection system of the highly sensitive fluorescence microscope part. In this combination, manipulations are now possible from the nanometer to the micrometer scales and the fluorescence detection system is sensitive enough even for localizing single molecules. In this paper, we applied the system as a precise intracellular injector (nanoplanter). Fluorescent beads were first chemically immobilized onto a ZnO whisker that was glued to an AFM tip and were injected into a living BALB/3T3 cell together with the whisker. It was demonstrated that the system could clearly show the result of injection, that is, the presence of a small number of fluorescent beads in the cell.     

Output power leveling of wind turbine Generator for all operating regions by pitch angle control

Wind energy is not constant and windmill output is proportional to the cube of wind speed, which causes the generated power of wind turbine generators (WTGs) to fluctuate. In order to reduce fluctuation, different methods are available to control the pitch angle of blades of windmill. In a previous work, we proposed the pitch angle control using minimum variance control, and output power leveling was achieved. However, it is a controlled output power for only rated wind speed region. This paper presents a control strategy based on average wind speed and standard deviation of wind speed and pitch angle control using a generalized predictive control in all operating regions for a WTG. The simulation results by using actual detailed model for wind power system show the effectiveness of the proposed method.