We present the laser system based on developed in-house Yb³⁺ doped silica fiber with a large core with a diameter of 21 µm, dedicated to high power applications. In the laser system, we achieved a maximum output power of 107 W limited by the available pump diode, in 25 m long fiber with high slope efficiency of 65 %. The laser generated at wavelength of 1080 nm and with beam quality of M_x² = 1.43 and M_y² = 1.44.