This paper presents the fabrication and characterization of a silicon-based optofluidic device for switching and splitting of a core stream with fluorescent dyes. The dye laser was created in the core, which is excited by a blue wavelength. The streams in the microchannel also form a liquid-core/liquid-cladding wave guiding system. The core is a glycerol solution, while the cladding is formed by two sheath streams of deionized water. The higher refractive index of the glycerol solution keeps the laser light inside the liquid core through total internal reflection. Keeping the flow rate of the core stream constant, splitting and switching was realized by controlling the flow rate ratio between the two sheath streams. The width of the core was controlled by hydrodynamic spreading or by the ratio between the core stream and the sheath streams. The fastest switching speed was about 300 ms, which is limited only by the response time of the pumping system. The wave guiding capability of this system was tested by coupling laser signals in and out of the fluidic system and measuring their intensity. The concepts and devices presented in this paper are suitable for applications with hydrodynamic focusing, sorting and optical detection for feed-back control.