Abstract: A method for manufacturing a semiconductor laser device includes forming a laminate having a semiconductor layer of a first conductivity type, an active layer and a semiconductor layer of a second conductivity type. The waveguide region is formed to guide light perpendicular to the direction of width by restricting the light from spreading in the direction of width in the active layer, such that the semiconductor laser device has a first waveguide region and a second waveguide region. The first waveguide region is formed to confine light within the limited active layer by means of a difference in the refractive index between the active layer and the regions on both sides of the active layer by limiting the width of the active layer. In forming the second waveguide region, light is confined therein by providing effective difference in refractive index in the active layer.

Abstract: A method for driving a semiconductor memory device includes a memory array having a plurality of memory cells arranged in rows and columns. Each memory cell includes a gate electrode formed on a semiconductor layer via a gate insulating film, a channel region disposed below the gate electrode, a source and a drain as diffusion regions disposed on both sides of the channel region and having a conductive type opposite to that of the channel region, and memory functional units formed on both sides of the gate electrode and having a function of retaining charges. The method includes the steps of: selecting a row line connected to the gate electrode of a memory cell to be selected; grounding a first column line connected to the source of the memory cell to be selected; and applying a first potential to a second column line and a second potential to a third column line at the same time.