关键词: 锁模激光器/
双波长锁模运转/
自启动锁模/
自发辐射放大
English Abstract
Dual-wavelength mode-locked Er-doped fiber laser based on optimizing gain fiber length
Shi Jun-Kai1,Ji Rong-Yi1,
Li Yao1,
Liu Ya1,
Zhou Wei-Hu1,2
1.Laboratory of Laser Measurement Technology, Academy of Opto-Electronics, Chinese Academy of Sciences, Beijing 100094, China;
2.University of Chinese Academy of Sciences, Beijing 101407, China
Fund Project:Project supported by the National Natural Science Foundation of China (Grant No.61475162),the Key Project of Bureau of International Co-operation,Chinese Academy of Sciences (Grant No.181811KYSB20160029),the Key Research Project of Bureau of Frontier Sciences and Education,Chinese Academy of Sciences (Grant No.QYZDY-SSW-JSC008),and the National Key Scientific Instruments and Equipment Development of China (Grant Nos.2011YQ120022,2014YQ090709).Received Date:22 March 2017
Accepted Date:28 April 2017
Published Online:05 July 2017
Abstract: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.
Keywords: mode-locked lasers/
dual-wavelength mode-locking operation/
self-starting mode-locking/
amplified spontaneous emission
