Single Longitudinal Mode Erbium-doped Fiber Research Articles

Compound four-cavity single-longitudinal mode fiber laser

A compound resonant cavity-type single longitudinal mode erbium-doped fiber laser is proposed and verified in this paper. We use a compound four-cavity to expand the longitudinal mode spacing of the laser and a homemade grating F-P filter and a saturable absorber to narrow the gain spectral bandwidth, enabling the laser to operate in a single-frequency state. Through theoretical analysis and experimental verification of the important roles of the main constructed fiber laser parts, the center wavelength of the laser output of 1550.06 nm is obtained, and the optical signal-to-noise ratio is 65 dB. In a 50 minute period, the wavelength fluctuation is exhibited along with the maximum power fluctuation of 0.28 dB. The value of the laser output linewidth is ∼250 Hz, measured by using the delayed self-heterodyne method.

S-band single longitudinal mode erbium-doped fiber laser with narrow linewidth based on passive multiple-subring resonator

A stable S-band single longitudinal mode (SLM) erbium-doped fiber laser (EDFL) with narrow linewidth based on passive multiple-subring resonator (PMSR) has been proposed and experimentally verified. The designed structure of PMSR can effectively expand the equivalent free spectral range and eliminate dense longitudinal modes. In addition, the dual-coupled fiber ring contained therein can form a narrow-band comb filter with good mode selection performance. Incorporating a section of saturable absorber can effectively suppress mode hopping and maintain stable SLM laser oscillation. The proposed S-band EDFL demonstrates that the linewidth is as narrow as 763.427 Hz. An optical signal-to-noise ratio of about 70 dB centered at 1499.770 nm and a wavelength stability of 0.04 nm have been obtained, respectively. This S-band EDFL is promising for the future S-band applications.

Gourd-shaped subring resonator-based single longitudinal mode erbium-doped fiber laser

A gourd-shaped subring resonator (GSR)-based single longitudinal mode erbium-doped fiber laser (EDFL) is proposed and experimentally demonstrated. The GSR can effectively expand the free spectral range of the fiber laser due to the Vernier effect and eliminate the dense longitudinal modes greatly. At the same time, an unpumped erbium-doped fiber serves as a saturable absorber to suppress mode hopping and stabilize frequency effectively. The experimental results show that the linewidth of the produced EDFL is ∼1.84 kHz and the output stability of power variation is nearly 0.02 dB. It can be seen that the EDFL could be exploited in applications where narrow linewidth and high power stability are both required.

A widely tunable fiber ring laser with closed loop control based on high-precision stepper motor

A tunable single-longitudinal mode erbium-doped fiber ring laser based on stepper motor and closed loop control is proposed and demonstrated. The system consists of an erbium-doped fiber (EDF), a tunable fiber Bragg grating (FBG) filter and a wavelength detector. The characteristics of output laser, such as output power, power stability and 3-dB linewidth, are investigated in the operation range of 1 531—1 569 nm. The repeated experimental results of the fiber laser show that the 3-dB linewidth is less than 17 ps, the side-mode suppression ratio (SMSR) is up to 60 dB, the output power is up to 1.37 dBm, and the power variation is less than 0.61 dB.

Photonic generation of microwave signal by beating a dual-wavelength single longitudinal mode erbium-doped fiber ring laser based on the polarization maintaining fiber bragg grating

A single-longitudinal-mode (SLM) dual-wavelength erbium-doped fiber (EDF) ring laser based on one polarization maintaining fiber Bragg grating (PMFBG) is demonstrated.Due to the polarization hole burning enhanced by the PMFBG, the laser can be designed to operate in stable dual-wavelength oscillation with a wavelength spacing of 0.182 nm at room temperature by adjusting a polarization controller. A section of unpumped EDF acting as a saturable absorber and a feedback fiber loop is used to ensure SLM operation in each of the two lasing lines. A microwave signal at 22.807 GHz is obtained by beating the dual-wavelength fiber laser at a photodetector. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:347–351, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27280