Open AccessDual-wavelength mode-locked Er-doped fiber laser based on optimizing gain fiber length
Author(s) -
Junkai Shi,
Rongyi Ji,
Yao Li,
Ya Liu,
Weihu Zhou
Publication year - 2017
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.66.134203
Subject(s) - materials science , fiber laser , optics , dispersion shifted fiber , optoelectronics , laser , optical fiber , wavelength , fiber optic sensor , physics
Recently,multi-wavelength pulsed lasers have become a research hotspot due to their versatile applications,such as precision spectroscopy,microwave/terahertz photonics,optical signal processing,and wavelength division multiplexed optical fiber communication systems.As a promising candidate,passively mode-locked fiber laser has the advantages of ultrashort pulse,ultrahigh peak power,compact structure and low-cost.In the existing multi-wavelength passively mode-locked fiber lasers,multi-wavelength mode-locked operation is achieved by adjusting the intracavity modulators to a proper state after laser has worked.It is inconvenient for practical use,so,its application scope is restricted.In this paper,a new method to achieve dual-wavelength mode-locked operation in an erbium-doped fiber laser is proposed. For an erbium-doped fiber,the peaks of both absorption and emission spectra overlap in the 1530 nm-region.So the emission light in the 1530 nm-region will be re-absorbed by the erbium-doped fiber with low pump power or long gain fiber.Utilizing the emission re-absorption effect,the gain spectrum can be modified by different lengths of gain fiber. In the experiment,an all-fiber ring cavity is adopted and a transmission-type semiconductor saturable absorber is used as a modelocker.The cavity consists of 3.2-m-long single mode fiber and an erbium-doped fiber.Gain fibers with different lengths are used in the cavity to reveal the dependence of emission re-absorption on both gain spectrum and mode-locked output spectrum.According to the experimental results,there are two humps in the amplified spontaneous emission spectrum located in the 1530 nm-region and 1560 nm-region,respectively.With the gain fiber length increasing, gain spectrum in the 1530 nm-region is suppressed,and gain intensity in the 1560 nm-region gradually surpasses that in the 1530 nm-region.Based on the experimental results,self-starting dual-wavelength mode-locked operation is achieved with a 31-cm-long gain fiber.The two spectral peaks with close intensity are located at 1532.4 nm and 1552.3 nm, respectively.The maximum output power is 4.8 mW at a repetition rate of 58.01 MHz and a signal-to-noise ratio of 58.2 dB.This self-starting dual-wavelength mode-locked erbium-doped fiber laser is convenient for practical use and can meet the requirements for many potential applications.