Mitigation of photodarkening to achieve laser oscillation and amplification with highly doped fibers
원문보기
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
H01S-003/30
H01S-003/03
출원번호
US-0508550
(2006-08-22)
등록번호
US-7477672
(2009-01-13)
발명자
/ 주소
Sinha,Supriyo
Digonnet,Michel J. F.
Byer,Robert L.
Limpert,Jens
출원인 / 주소
The Board of Trustees of the Leland Stanford Junior University
대리인 / 주소
Lumen Patent Firm
인용정보
피인용 횟수 :
5인용 특허 :
4
초록▼
Photodarkening in active fiber or waveguide devices (e.g. lasers, amplifiers, and incoherent sources such as ASE sources) can be reduced by altering the dopant concentration along the length of the doped fiber. A fiber or waveguide device includes two or more intentionally doped fiber or waveguide
Photodarkening in active fiber or waveguide devices (e.g. lasers, amplifiers, and incoherent sources such as ASE sources) can be reduced by altering the dopant concentration along the length of the doped fiber. A fiber or waveguide device includes two or more intentionally doped fiber or waveguide sections having different concentrations of one or more dopants. The dopants provide optical gain responsive to pump radiation provided to the fiber device by a pump source. A first optical intensity in a first of the fiber or waveguide sections is greater than a second optical intensity in a second of the fiber or waveguide sections. A first dopant concentration in the first fiber or waveguide section is lower than a second dopant concentration in the second fiber or waveguide section. Thus the dopant concentration is reduced in sections of the fiber or waveguide device having a higher optical intensity. The optical intensity can be due to pump radiation and/or signal radiation. Reduced dopant concentration in regions of high optical intensity reduces photodarkening.
대표청구항▼
The invention claimed is: 1. A waveguide gain module comprising: a source of pump radiation; a waveguide configured to receive the pump radiation and to provide optical gain, wherein the waveguide includes two or more intentionally doped waveguide sections disposed in series and having different co
The invention claimed is: 1. A waveguide gain module comprising: a source of pump radiation; a waveguide configured to receive the pump radiation and to provide optical gain, wherein the waveguide includes two or more intentionally doped waveguide sections disposed in series and having different concentrations of one or more dopants; wherein the one or more dopants, responsive to the pump radiation, provide the optical gain; wherein a first optical intensity in the first waveguide section is greater than a second optical intensity in the second waveguide section; and wherein a first doping concentration in the first waveguide section is lower than a second doping concentration in the second waveguide section; wherein each of said intentionally doped waveguide sections has a length less than 10 meters; wherein each of said intentionally doped waveguide sections has a small signal pump absorption greater than 50 dB/m. 2. The waveguide gain module of claim 1, wherein a doping concentration changes continuously between said first and said second waveguide sections. 3. The waveguide gain module of claim 1, wherein said first and said second waveguide sections are spliced together. 4. The waveguide gain module of claim 1, wherein said dopants are selected from the group consisting of Er, Yb, Nd, Tm, Pr, Sm, Ho, and Bi. 5. The waveguide gain module of claim 1, wherein said doped waveguide sections are selected from the group consisting of silica fiber, phosphate fiber, fluoride fiber, chalcogenide fiber, telluride fiber, polarization-maintaining fiber, standard single-mode fiber, large-mode-area fiber, double-clad fiber, holey fiber, integrated-optic waveguides, photonic-bandgap waveguides, circular cross-section waveguides, and rectangular cross-section waveguides. 6. The waveguide gain module of claim 1, further comprising one or more additional sources of additional pump radiation, wherein said waveguide is configured to receive the additional pump radiation, and wherein said one or more dopants, responsive to the additional pump radiation, provide optical gain. 7. The waveguide gain module of claim 1, wherein said first and second optical intensities are substantially intensities of said pump radiation. 8. The waveguide gain module of claim 1, wherein said first and second optical intensities are substantially intensities of signal radiation. 9. The waveguide gain module of claim 1, wherein said first and second optical intensities are combined intensities of said pump radiation and signal radiation. 10. An optical amplifier or an optical source comprising the waveguide gain module of claim 1. 11. The waveguide gain module of claim 1, wherein a dopant concentration profile along said waveguide is selected to optimize a compromise between minimizing photodarkening and maximizing output power. 12. A fiber gain module comprising: a source of pump radiation; a doped fiber configured to receive the pump radiation and to provide optical gain, wherein the doped fiber includes two or more intentionally doped fiber sections disposed in series and having different concentrations of one or more dopants; wherein the one or more dopants, responsive to the pump radiation, provide the optical gain; wherein a first optical intensity in the first fiber section is greater than a second optical intensity in the second fiber section; and wherein a first doping concentration in the first fiber section is lower than a second doping concentration in the second fiber section; wherein each of said intentionally doped fiber sections has a length less than 10 meters; wherein each of said intentionally doped fiber sections has a small signal pump absorption greater than 50 dB/m. 13. An optical source or an optical amplifier comprising the fiber gain module of claim 12. 14. A fiber laser comprising the fiber gain module of claim 12 disposed within a fiber resonator, wherein laser output radiation is emitted from the fiber resonator. 15. The fiber laser of claim 14, wherein said laser output radiation includes radiation having a wavelength in a range from about 1120 nm to about 1200 nm. 16. The fiber laser of claim 14, wherein said fiber laser is either a continuous-wave laser or a pulsed laser. 17. The fiber laser of claim 14, wherein said fiber resonator comprises a standing-wave resonator or a traveling-wave resonator. 18. The fiber laser of claim 14, wherein said fiber resonator comprises a standing-wave resonator, and wherein the standing-wave resonator comprises narrow-band feedback elements having center wavelengths corresponding to a wavelength of said laser output radiation. 19. The fiber laser of claim 18, wherein said narrow-band feedback elements comprise fiber Bragg gratings. 20. The fiber laser of claim 14, further comprising a frequency doubler configured to receive said laser output radiation and to provide second harmonic radiation having twice the frequency of said laser output radiation. 21. The fiber laser of claim 20, wherein said second-harmonic radiation includes radiation having a wavelength in a range from about 560 nm to about 600 nm. 22. The fiber laser of claim 20, wherein said frequency doubler comprises a nonlinear optical waveguide. 23. The fiber laser of claim 20, wherein said frequency doubler comprises a nonlinear optical bulk crystal. 24. The fiber laser of claim 14, further comprising: a power amplifier configured to receive said laser output radiation and to provide amplified radiation having a larger power than said laser output radiation; and a frequency doubler configured to receive said amplified radiation and to provide second-harmonic radiation having twice the frequency of said laser output radiation. 25. A method of providing optical gain in a waveguide, the method comprising: providing pump radiation to a waveguide, wherein the waveguide includes two or more intentionally doped waveguide sections disposed in series having different concentrations of one or more dopants; wherein the one or more dopants, responsive to the pump radiation, provide optical gain; wherein a first optical intensity in a first of the waveguide sections is greater than a second optical intensity in a second of the waveguide sections; and wherein a first doping concentration in the first waveguide section is lower than a second doping concentration in the second waveguide section, wherein each of said intentionally doped waveguide sections has a length less than 10 meters; wherein each of said intentionally doped waveguide sections has a small signal pump absorption greater than 50 dB/m.
Morasse, Bertrand; De Sandro, Jean-Philippe; Gagnon, Eric, Optically active glass and optical fiber with reduced photodarkening and method for reducing photodarkening.
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