Jiayu Huo

Soliton molecules in a fiber laser mode-locked by a graphene-based saturable absorber

We have experimentally investigated a novel kind of soliton molecule in a graphene-based mode-locking fiber laser with anomalous dispersion. The soliton molecule exhibits a stable rectangular profile on the oscilloscope, whereas it shows randomly distributed peaks in the autocorrelation trace, which indicates that the temporal separation of pulses in the molecule is varying all the time. The optical spectrum is modulated with a depth of about 7 dB over the whole profile, induced by the interaction of the intra-molecule solitons. The experimental results demonstrate that solitons in the pulse molecule oscillate randomly in temporal domain and the neighboring molecules are temporally separated by a fundamental cavity repetition rate, which is very different from that of the multi-solitons or bound-state solitons.

Signal recognition of the optical fiber vibration sensor based on two-level feature extraction

To deal with the high false alarm rate in optical fiber Michelson interferometer, a two-level feature extraction algorithm based on threshold-crossing rate and sparse auto-encoders is proposed. The threshold-crossing rate algorithm is used as the first level feature extraction to identify whether vibration occurs. If vibrations occur, the sparse auto-encoders algorithm is applied to extract high dimension features of vibration signals, and then the extraction feature will be sent to a classifier to recognize vibration pattern. Experiment results show that this method can effectively identify five kinds of vibrations and reduce false rate.

Influence of pumping schemes on the characteristics of self-similar pulses in a passively mode-locked fiber laser

Abstract. Self-similar pulses are one of the domestic and international research hotspots in the field of nonlinear fiber optics because it can suppress optical wave breaking at high energies. The influence of pumping schemes on the characteristics of self-similar pulses in a passively mode-locked Yb-doped fiber laser is theoretically investigated. The temporal profile and optical spectrum of self-similar pulses in passively mode-locked fiber lasers of different pumping schemes are obtained in the simulation. This study focuses on analyzing the influence of gain bandwidth of gain fiber on the pulse duration, peak power, and single-pulse energy of self-similar pulses.

Influences of GVD on the characteristics of soliton in a passively mode-locked Er-doped fiber laser

Abstract In this paper, the characteristics of soliton in a passively mode-locked Er-doped fiber laser modeled by a non-distributed model are numerically investigated with the split-step Fourier method. Based on the analysis and model, sech 2 -shaped soliton is obtained by controlling the group velocity dispersion (GVD) and small-signal gain of the gain fiber. The law that the dispersion influences the characteristics of soliton in the mode-locked fiber laser is researched in net-cavity averaged anomalous dispersion regime.

Investigation on gain-clamped characteristics of ring cavity L-band EDFA

A novel gain-clamped Long wavelength band erbium doped fiber amplifier (L-band EDFA) based on ring erbium-doped fiber laser cavity was demonstrated. By using a fiber Bragg grating (FBG) at the output end of the amplifier, a portion of forward conventional band (C-band) amplified spontaneous emission (ASE) was reflected back into the system, this new design provided a good gain clamping and decreased noise effectively. It used 1480nm laser diode (LD) to pump high Er3+ −concentration erbium-doped fiber for higher efficiency and lower noise figure (NF). The gain was clamped at 17.5dB with a variation of 0.3 dB from input signal power of -30dBm to -12dBm for a pump power of 180mW. By adjusting the intra-cavity loss, the gain reached 19.78dB with inputting small signal and NF below 5dB was obtained. At the longer wavelength (1614nm) of L-band 9.2dB gain was obtained.

Study on parameter optimization in a passively mode-locked Erbium-doped fiber laser

Abstract Optical soliton communication is the frontier research topic of optical fiber communication. In this paper, we study optical solitons generated by passively mode-locked Erbium-doped (Er-doped) fiber (EDF) laser. We analyze the variation of nonlinear equilibrium point parameter N of the passively mode-locked EDF laser in the role of group-velocity dispersion (GVD) and small-signal gain, and adjusting system parameter N is as close as to possible to 1. The ground state first-order optical soliton which generated through system parameter optimization of the passively mode-locked EDF laser will improve the efficiency and stability of optical soliton communication system. The research of this paper will have provided the theoretical foundation of parameter optimization in a passively mode-locked EDF laser. And it will be possible for the passively mode-locked fiber laser in optical fiber communication system to be applied from the laboratory stage to the practical application.

Influences of finite gain bandwidth on dissipative solitons in passively mode-locked Er-doped fiber laser

Abstract Dissipative solitons in the passively mode-locked fiber lasers based on the gain medium of erbium-doped (Er-doped) fiber have attracted a lot of interest in recent years. In this paper, we study the influences of finite gain bandwidth on dissipative solitons in passively mode-locked Er-doped fiber laser. We investigate the influences of the finite gain bandwidth on pulse duration, pulse peak power and single pulse energy of dissipative solitons. The results show that gain bandwidth of the gain medium has influence on dissipative soliton characteristics in passively mode-locked Er-doped fiber laser. The research in this paper has important theoretical and practical significance.

Temperature and Strain Characteristic Analysis of Fiber Bragg Grating Sensor

A novel method is proposed to simulate temperature and strain characteristic of fiber Bragg grating (FBG) sensor with OptiGrating software, whose temperature characteristic is investigated experimentally with FBG sensing system based on broadband source one step further, both the simulation and experiment results show that the Bragg wavelength shift is linearly proportional to uniform temperature distribution. The parameters of FBG sensing system based on fiber ring laser have been optimized for good sensing performance, high signal-to-noise ratio (SNR) and powerful multiplexing capacity indicate its effectiveness and reliability in the application of long-haul sensing system.

Fiber grating current array based on tunable fiber laser

A current sensor array which consists of tunable fiber laser, Giant Magnetostrictive Material (GMM) and fiber grating is presented. The long-haul experiment is operated on the basis of current sensor unit about 21km. In general, the results of the design of the system is credible and qualified for the designing demand. And then a current sensor array is composed of four current sensor units in 21km long-haul. The sensing properties of the wavelength divided multiplex (WDM) and time divided multiplex (TDM) is demonstrated. The wavelength resolution of the measurements is 0.002 nm and current resolution is 6.55mA, due to the high sensitivity photo detection system. While the work current go up from 1200mA to2300mA, Sensitivity of the wavelength will be maximum.

Ring-cavity Er/Yb co-doped fiber laser and its mode characteristics

A ring-cavity Er/Yb co-doped fiber laser (EYDFL) was designed and the characteristics was studied in this paper. It used 1064nm Nd:YAG laser as its pump, and the gain medium is a 4.1m-long EYDF. The single longitudinal-mode operation is realized by introducing a fiber Bragg grating (FBG) as narrow wavelength-selective element, and a section of EDF not-pumped as saturable absorber. The fiber laser resonator has been optimized, and the stable laser output with single longitudinal-mode was got. In the simulation and experimental study, the difference of fiber laser output power using output coupler in different coupling ratio has been studied. The optimal coupling ratio testified in experiments was near 80 percents. The effects and influences of saturable absorber on characteristics of output laser mode are analyzed.