We report the results obtained by using a newly designed 300-µm-core-diameter Yb-doped fiber with a large cladding absorption of 23 dB/m at 976 nm. An average power of 512 W, a maximum pulse energy of 51.2 mJ laser is realized using the 300-µm-core Yb-doped fiber in the main amplifier with a slope efficiency of 72%. The entire laser system adopts an all-fiber construction with pulse control system. These results extend average power and peak power of nanosecond all fiber-based laser, exceeding to the 500 W and 1 MW regime simultaneously for the first time to the best of our knowledge.
We demonstrate the transmission of a 100 MW-peak-power ultrafast laser through a 5-m anti-resonant hollow-core fiber (AR-HCF) with a pumpable armored tube for air exhaust. The AR-HCF consists of a 45-μm-hollow-core and seven untouched capillaries with an attenuation of 0.11 dB/m measured at a wavelength of 1030 nm. We investigate the effect of air-filling and vacuum pumping on transmission efficiency and pulse distortion. The comparison reveals the importance of controlling air concentration in hollow-core fibers (HCFs) for achieving high transmission efficiency and pulse quality. With the suppression of air concentration, the transmission efficiency increases from 61% to 72%, and pulse distortion is effectively controlled. The results demonstrate the potential of AR-HCFs for high-power ultrafast laser delivery systems for various applications. The pumpable armored tube design provides a simple and effective solution to suppress self-phase modulation (SPM) and enable flexible beam delivery.
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