Fiber-amplifiers with all-fiber optical isolator

1. A fiber-optic device having input and output and comprising:

at least one pump laser source;

at least one first rare-earth doped optical fiber having a material composition enabling amplification of light passing therethrough;

at least one all-fiber optical isolator including a second optical fiber having at least first, second, and third separated from one another sections, the first and third sections of the second optical fiber being associated with Faraday rotation and having respective cores with a first doping concentration of 55% (wt./wt.) to 85% (wt./wt.) of a first rare-earth oxide, and

at least three magnetic cells each having a hollow, said at least three magnetic cells arranged in a sequence such that the same magnetic poles of immediately neighboring cells are facing one another, said first and third sections of the second optical fiber respectively disposed in the hollows of first and third magnetic cells that are separated by a second magnetic cell,

wherein the fiber-optic device is an all-fiber fiber-optic device and a light-path of the fiber-optic device defined between the input and the output is devoid of a free-space region, immediately neighboring fiber-optic elements of the fiber-optic device being fusion-spliced together,

wherein the second optical fiber includes a cladding having a second doping concentration of 55%-85% (wt./wt.) of a second rare-earth oxide,

and

wherein the second rare-earth oxide is selected from the group consisting of Pr2O3, Nd2O3, Pm2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3, La2O3, Ga2O3, Ce2O3, and Lu2O3, and a refractive index of the cladding is lower than a refractive index of the core.

2. A fiber-optic device according to claim 1 , wherein the second optical fiber includes a multicomponent glass optical fiber and the first rare-earth oxide is selected from the group consisting of Pr2O3, Nd2O3, Pm2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3, La2O3, Ga2O3, Ce2O3, and Lu2O3.

3. A fiber-optic device according to claim 1 , adapted to generate a power output characterized by at least one of an average power in excess of 100 W or a peak power in excess of 5 kW.

4. A fiber-optic-device according to claim 1 , adapted to generate a light output having single-mode characteristics or multi-mode spatial characteristics.

5. A fiber-optic device according to claim 1 , structured to generate a light output with polychromatic spectral content.

6. A fiber-optic device according to claim 1 , structured to generate a light output including at least one of a continuous-wave output and a pulsed output.

7. A fiber-optic device according to claim 6 , wherein the light output includes a continuous-wave output and a pulsed output.

8. A fiber-optic device of claim 1 ,

wherein the first section of the second optical fiber, when exposed to a magnetic field flux density, is characterized by a first Faraday rotation angle and a first direction of Faraday rotation,

wherein the third section of the second optical fiber, when exposed to said magnetic field flux density, is characterized by a third Faraday rotation angle and a third direction of Faraday rotation, and

said first direction of Faraday rotation is the same to the third direction of Faraday rotation.

9. A fiber-optic device according to claim 1 , wherein magnetic cells in a pair of immediately neighboring magnetic cells are axially separated from one another.

10. A fiber-optic device of claim 1 , wherein each of the magnetic cells is in physical contact with at least one other of the magnetic cells.

11. A fiber-optic device according to claim 1 , wherein sections of the second optical fiber associated with Faraday rotation and enclosed in different magnetic cells are different with respect to at least one of a corresponding doping material and a corresponding concentration of said doping material.

12. A fiber-optic device according to claim 1 having a first port and a second port, the fiber-optic device further comprising a first optical-fiber-based polarizer defining the first port and a second optical-fiber-based polarizer defining the second port.