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Gratings with longitudinal variations in coupling coefficients: super-efficiency and unidirectionality in distributed feedback Raman fiber lasers

Amirhossein Tehranchi and Raman Kashyap

Article (2020)

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Abstract

We propose a technique to design highly-efficient and -unidirectional DFB Raman fiber lasers based on the engineering of the grating's coupling coefficient including a π-phase shift position in the fiber. For this purpose, first the ideal intra-cavity signal powers for different pump power levels are determined for given fiber lengths. Then, the sum and difference between the counter-propagating wave intensities at each small segment within fiber lengths are calculated resulting in determining the ideal grating's coupling functions for co- and contra-directional-pumping. The steady-state behavior of the laser using realistic parameters is finally simulated for modified coupling functions considering the Kerr nonlinearity. For a 10 W co-directional-pumped, ∼1 m long single-mode super-efficient DFB, a ∼50% increase in the laser efficiency, more than 44 dB reduction in contra-directional lasing power, ∼15 times drop in the peak power of intra-cavity signal and ∼38% decrease in the unused-pump power are found, compared to those in a standard DFB with the same coupling-length product. Although an enhanced nonlinear refractive index due to thermal gradient reduces the output power of such lasers, it is shown that the super-efficient laser presents a better performance than the standard one, under such conditions.

Uncontrolled Keywords

Bragg gratings; Raman lasers; fiber optic

Subjects: 2500 Electrical and electronic engineering > 2500 Electrical and electronic engineering
3100 Physics > 3100 Physics
3100 Physics > 3111 Lasers
3100 Physics > 3112 Photonics
Department: Department of Electrical Engineering
Department of Engineering Physics
Research Center: Other
Funders: CRSNG / NSERC
PolyPublie URL: https://publications.polymtl.ca/9311/
Journal Title: New Journal of Physics (vol. 22, no. 10)
Publisher: IOP Publishing Ltd
DOI: 10.1088/1367-2630/abbc2a
Official URL: https://doi.org/10.1088/1367-2630/abbc2a
Date Deposited: 14 Aug 2023 17:23
Last Modified: 05 Apr 2024 18:41
Cite in APA 7: Tehranchi, A., & Kashyap, R. (2020). Gratings with longitudinal variations in coupling coefficients: super-efficiency and unidirectionality in distributed feedback Raman fiber lasers. New Journal of Physics, 22(10), 103022 (10 pages). https://doi.org/10.1088/1367-2630/abbc2a

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