a fiber ring laser, using erbium-ytterbium co-doped double clad fiber is proposed and demonstrated to produce a medium power multiwavelength fiber laser. the experimental results show that the ring resonator configuration can produce more output power compared to a laser based on bidirectional pumping scheme in fabry-perot resonator configuration. to stabilize the lasing lines we used an unpumped erbium doped fiber as saturable absorber. a sagnac loop interferometer is used as a filter inside the cavity and its effect has been explored. we can produce a maximum four lasing lines which are stable for more than 2 hours when observed through osa with a resolution of 0.05 run. the maximum output power obtained from the laser is more than 100 mw. our best result at room temperature is simultaneous oscillations of two single-mode laser wavelengths with a maximum output power of 60 mw when observed through a scanning fabry-perot spectrum analyzer of resolution 27 mhz.