Coherent Fiber Laser Research Articles

Statistical properties of partially coherent cw fiber lasers

We perform a detailed quantitative numerical analysis of a partially coherent quasi-cw fiber laser on the example of a high-Q normal dispersion cavity Raman fiber laser. The key role of precise spectral performances of fiber Bragg gratings forming the laser cavity is clarified. It is shown that cross-phase modulation between the pump and Stokes waves does not affect the generation. Amplitudes of different longitudinal modes strongly fluctuate, obeying the Gaussian distribution. As the intensity statistics is noticeably nonexponential, longitudinal modes should be correlated.

Scalability and stability of a coherent fiber laser array using fiber couplers

A coherent fiber laser array using fiber couplers is discussed. The array modes are analyzed and determined using coupled mode theory. A numerical analysis of the phase property for a 19-fiber array is performed and the results show that the array can achieve a quasi-in-phase state. The stability and the scalability of coherent combination are investigated by simulations via changing the fiber grating reflectivity, the pump parameter, and the cavity length. Considering the mutual coupling between fiber lasers and the mismatch among fiber lengths, we trace the relative phases between array elements and further provide the evidence of coherent combining for the 19-fiber array. With the increase in the fiber elements, although the system is required to operate at a lower grating reflectivity for achieving a stable laser output, the output power increases nonlinearly.

位相結合ファイバレーザーの波長ならびに偏波不安定性

位相結合ファイバレーザーの波長ならびに偏波不安定性

SPGD算法在光纤激光相干阵列光束控制中的应用

SPGD算法在光纤激光相干阵列光束控制中的应用

Optimal Truncation of Element Beam in a Coherent Fiber Laser Array

The beam quality of a coherent fiber laser array often suffers from the low fill factor of the Gaussian laser array. One simple and effective approach to improve the fill factor is to truncate the array element properly. An analytical expression for far-field intensity distribution of a truncated coherent fiber laser array is derived. Optimal truncation of the element beam in different coherent fiber laser arrays is obtained by using energy encircled in the far-field central-lobe as the beam quality criterion. By optimal truncation, energy encircled in the central-lobe can be 97% compared with the ideal case. The shift in optimal truncation parameter in the case of phase noise is also analyzed.

Numerical research on self-organized coherent fiber laser arrays with circulating field theory

Self-organized coherent fiber laser arrays of interferometer configuration are researched numerically with circulating field theory. The numerical results agree well with the experimental observations. The self-organization mechanism of the array is verified to be longitudinal mode selection in an interferometer resonator. Influences of the arm length difference and the number of fiber lasers on the performance of the coherent fiber laser array are discussed in detail. It is proved that the random length deviation is the key factor that induces the degradation of the combining efficiency.

Novel intra-cavity self-organization coherent erbium-doped fiber laser

A novel all-fiber self-organization coherent Erbium-doped fiber laser is proposed and demonstrated. The laser system is composed of two independent lasers. When each of the two branch lasers operates independently, the output power is 10. 41mW and 8.69 mW respectively. By adjusting a polarization controller (PC), the two lasers achieve coherent coupling, and the output power is 24.4 mW, which is more than two times that the single laser yields. Furthermore, we bring forward and discuss the factor estimating the effect of coherent combination—coherent coupling factor. The value of growth factor to evaluate the effect of coherent combining is 1.27. The coherent fiber laser has the advantages of simple structure, high efficiency and single frequency, which conduce to coherent coupling easily.