In this paper, an innovation coherent beam combining (CBC) architecture to generate the structured light beams array was proposed and experimented. The simulation and experimental results reveal that the optical vortex beams array (OVBA) with multi-modes can be generated effectively in the far field. The OVBA is composed of multiple sub-OVB in the intensity distribution. Furthermore, the number of OVBs can be modulated by changing the fill factor of the laser array in the near field. In particular, the performance of a OVBA copier was observed, which may deepen the understanding of creating the structured light fields by CBC technique. The experiment results were in excellent agreement with the simulation results. This work could provide valuable and practical reference on generation and manipulation of high power structured light beams
Single trench fiber (STF) is one kind of promising novel fibers. In this paper, we design and fabricate a piece of ytterbium-doped STF. The core diameter of the homemade STF is 30 μm and the cladding diameter is 250 μm. Based on this self-developed STF, we have constructed an all-fiberized fiber amplifier that is operating under a continuous-wave regime at 1070 nm wavelength. The maximum output power of the system reaches 1.5 kW, which, to the best of our knowledge, is the highest output power of STF-based laser systems. The M2 is measured to be 1.65 at 1.36 kW and 1.92 at the highest output power respectively. The slope efficiency of amplification system is 68%. The performance of the system can be further enhanced by optimizing the fiber design and system structure.
All-solid photonic bandgap fiber (AS-PBGF) has been an unrivalled platform for the effective mode area (EMA) scaling of large-mode-area fiber and the selective spectral filtering. Super-large EMA scheme assisted by the multiple resonance mechanism is also achievable while maintaining the robust single-mode (RSM) operation. In the current work, we have proposed aother modified multi-resonant AS-PBGF with some high-index nodes are replaced by the background material. By extending the multi-resonant coupling concept, a specially designed microstructural cladding, with multiresonant cores in the inner layers and leakage channels in the outermost layer, is employed to generate broadband resonance and modal dissipation of high-order-modes (HOMs) under bent configuration. Sufficient confinements on the modal distribution of fundamental mode (FM) are retained by adjusting the arrangement of Ge-doped rods in the microstructure cladding precisely, and the rotational symmetry of the proposed AS-PBGF makes it insensitive to bending direction. The missing Ge-doped rods in each layer are properly designed to stress differential bending loss between FM and HOMs with high loss ratio. Bending loss of FM less than 0.05 dB/m and high loss ratio over 200 times are always available and independent of bending direction. An EMA greater than 900 μm2 and a loss ratio up to ~ 495 can be obtained under the bending radius of 45 cm.
In this study, we design and fabricate a novel type of active fiber——double-tapered double-clad fiber (DT-DCF). Based on this self-developed DT-DCF, we have constructed an all-fiberized fiber amplifier that is operating under a continuous-wave (CW) regime at 1080 nm wavelength. The maximum output power of the system reaches 4 kW, which, to the best of our knowledge, is the highest output power of tapered fiber-based laser systems. The amplifier exhibits near-single-mode beam quality (M2=1.33) at the highest output power with a slope efficiency of 83%. Our result successfully verifies the potential of power scalability of DT-DCF, and the performance of our system can be further enhanced by fiber design optimization.
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