Optical amplifier using optical fiber

1. An optical amplifier using an optical fiber, the optical amplifier comprising:

a single-mode optical fiber in which a plurality of rare earth elements is doped simultaneously;

first and second optical fiber gratings disposed at opposite sides of the optical fiber, respectively, and totally reflecting light having a wavelength in a specific range;

a pumping light source configured to generate a pumping light to excite rare earth ions in the optical fiber; and

an optical coupler connected to the optical fiber and configured to transmit a light signal generated from a light source and the pumping light generated from the pumping light source to the optical fiber,

wherein

erbium and thulium are doped in the optical fiber,

the light signal has a wavelength in a range from 1,800 nm to 2,100 nm, and

the pumping light has a wavelength in a range from 970 nm to 990 nm.

2. The optical amplifier using the optical fiber of claim 1 , wherein a doping ratio of the erbium to the thulium is set in a range from 1 to 2 to 1 to 10.

3. The optical amplifier using the optical fiber of claims 2 , wherein a doping concentration of the erbium is set to be 1,000 ppm, and a doping concentration of the thulium is set to be in a range from 2,000 ppm to 10,000 ppm.

4. The optical amplifier using the optical fiber of claim 1 , wherein the light totally reflected by the first and the second optical fiber grating has a specific wavelength in a range from 1,550 nm to 1,610 nm.