Abstract: To provide a Mach-Zehnder (MZ) type semiconductor optical modulation element that can be used as a modulator, which is ultrafast and excellent in electrical stability. A semiconductor optical modulation element of a Mach-Zehnder type that performs modulation of light using a refractive index modulation region where a refractive index of the light guided to an optical waveguide is modulated and an input and output region where multiplexing/demultiplexing of the light split in the refractive index modulation region is performed, characterized in that in the refractive index modulation region of the optical waveguide, an n-type clad layer, an i core layer, and a p-type clad layer are stacked in the order from a top layer on a substrate surface equivalent to a (100) plane of a sphalerite-type seminsulating semiconductor crystal substrate, the n-type clad layer is formed in a ridge shape in an inverted mesa direction, and a capacitancl-oaded electrode is provided on the n-type clad layer.

Abstract: This invention provides a high-frequency line adopting a structure to suppress an impedance variation and occurrence of an excessive power loss in high-frequency wiring having intersection with an optical waveguide. A high-frequency line is a microstrip line which has a basic configuration of stacking a ground electrode, a dielectric layer, and a signal electrode in this order on a SI-InP substrate. In addition, as shown in a transverse sectional view, an optical waveguide core made of InP-based semiconductor intersects with the high-frequency line in a crossing manner. A width of the signal electrode is partially increased in a certain region covering the intersection with the optical waveguide along a propagating direction of the high-frequency line. In the microstrip line, the width of the signal electrode is partially increased from w1 to w2, and characteristic impedance is thus reduced as compared to one with the uniform width w1.

Abstract: To provide a Mach-Zehnder (MZ) type semiconductor optical modulation element that can be used as a modulator, which is ultrafast and excellent in electrical stability. A semiconductor optical modulation element of a Mach-Zehnder type that performs modulation of light using a refractive index modulation region where a refractive index of the light guided to an optical waveguide is modulated and an input and output region where multiplexing/demultiplexing of the light split in the refractive index modulation region is performed, characterized in that in the refractive index modulation region of the optical waveguide, an n-type clad layer, an i core layer, and a p-type clad layer are stacked in the order from a top layer on a substrate surface equivalent to a (100) plane of a sphalerite-type semi-insulating semiconductor crystal substrate, the n-type clad layer is formed in a ridge shape in an inverted mesa direction, and a capacitance-loaded electrode is provided on the n-type clad layer.

Abstract: The invention provides a useful vehicle dispatching system. Server 60 estimates an approximate location of a passenger on the basis of the area code transmitted from server 40. Server 60 transmits a list of landmarks located in the area corresponding to the area code, and the list is thereby provided to the passenger carrying mobile station 10. The passenger selects a desired landmark to which a vehicle should be dispatched. Server 60 determines the location of the landmark by referring to the landmark database; and determines which vehicles 20 are located proximate to the landmark by referring to the vehicle database. Server 60 transmits the information on the determined vehicles 20 to mobile station 10, and the information is thereby provided to the passenger. The passenger selects a desired vehicle 20 to make a telephone call to the driver of vehicle 20. Thus, the passenger may directly talk to the driver.

Abstract: The invention provides a useful vehicle dispatching system. Server 60 estimates an approximate location of a passenger on the basis of the area code transmitted from server 40. Server 60 transmits a list of landmarks located in the area corresponding to the area code, and the list is thereby provided to the passenger carrying mobile station 10. The passenger selects a desired landmark to which a vehicle should be dispatched. Server 60 determines the location of the landmark by referring to the landmark database; and determines which vehicles 20 are located proximate to the landmark by referring to the vehicle database. Server 60 transmits the information on the determined vehicles 20 to mobile station 10, and the information is thereby provided to the passenger. The passenger selects a desired vehicle 20 to make a telephone call to the driver of vehicle 20 of the car 20. Thus, the passenger may directly talk to the driver.