Four-wave mixing (FWM) phenomenon can be produced by using a different refractive index of the optical fiber in an erbium doped fiber laser system. In our study, we used a 20 meter length of Photonics crystal fiber (PCF) to generate multiwavelength signals. Variable optical attenuator is employed in the setup to study its effect on the output signals. Results show that uniform signals were obtained by using the VOA to suppress other modes of wavelengths which occurred before placing the VOA. New lasing wavelength at 1530.445 nm, 1531.450 nm, 1531.960 and 1532.415 nm were produced uniformly.