Open AccessOptically controlled tunable ultra-narrow linewidth fiber laser with Rayleigh backscattering and saturable absorption ring
Author(s) -
Yujia Li,
Ligang Huang,
Lei Gao,
Tianyi Lan,
Yulong Cao,
Iroegbu Paul Ikechukwu,
Leilei Shi,
Yongfeng Liu,
Fuhui Li,
Tao Zhu
Publication year - 2018
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.26.026896
Subject(s) - laser linewidth , materials science , optics , fiber laser , fiber bragg grating , laser , saturable absorption , lasing threshold , optoelectronics , wavelength , physics
We propose an optically controlled tunable ultra-narrow linewidth fiber laser assisted with the mode selection induced by a saturable absorption interference ring and linewidth narrowing of fiber Rayleigh backscattering (RBS). The interference ring serves as an artificial narrow-band filter, which conduces to the laser operating at a single-frequency state. To realize narrower linewidths, additional single-mode fiber is utilized to accumulate a weak RBS feedback. On basis of inherent wavelength universality of this linewidth-narrowing mechanism, an all-optical technique is employed to enable linear and stable tunability of the laser. Cooperating with a micro-fiber Bragg grating covered by graphene, the lasing wavelength is tuned precisely and reversibly with a sensitivity of 12.4 pm/mW and a linear fitting R2 over 0.997 by changing the power of a controlling beam. During a stability test with the controlling pump power fixed, the long-term free-running power fluctuation is less than 0.5%. The Output laser linewidth is compressed to be ~200 Hz, which is also confirmed by the descending frequency noise spectrum.