The present invention relates to an entire normal dispersion optical fiber laser resonator having a repetition rate of less than 10 MHz which is a mode locked through a saturation absorber and a nonlinear polarization rotation phenomenon, comprising a laser diode which outputs a laser pump light; a wavelength divider which couples the laser pump light outputted in the laser diode inside the resonator; a yitterbium addition optical fiber which amplifies a pulse of the resonator that penetrates the wavelength divider using the coupled pump light; a first wavelength plate (1/4) and a first wavelength plate (1/2) which convert the polarization of a laser light that penetrates the optical fiber; a first polarization light divider which separates the polarization of the laser light that penetrates each of the first wavelength plates; a birefringence determination based optical filter and an interference filter which respectively filters the penetration band of the light that penetrates the first polarization light divider; an optical shielding device which blocks a part of the light in the polarization that penetrates the interference filter; a second wavelength plate (1/2) which converts the polarization of the light that penetrates the optical shielding device; a second polarization light divider which separates the polarization of the laser light that penetrates the second wavelength plate; a second wavelength plate (1/4) which converts the polarization of the light that penetrates the second polarization light divider; a lens which penetrates the light that penetrates the second wavelength plate; a saturation absorber which induces a mode locking of the light that penetrates the lens; a third wavelength plate (1/4) which converts the polarization of the mode locked laser light; and a single mode optical fiber which induces the low repetition rate of the laser light that penetrates the third wavelength plate, wherein the laser light outputted in the laser diode is sequentially penetrated.
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