Fig. 1. (a) Measurement scheme of PD loss; (b) structure of high-power MOPA system.

Fig. 2. Absorption spectra before and after 300 min pumping of (a) the pristine N1 fiber and (b) the H2-loaded N1 fiber.

Fig. 3. PD-induced excess loss and fitting curve at 633, 702, 810, and 1041 nm for (a) the pristine N1 fiber and (b) the H2-loaded N1 fiber.

Fig. 4. Time dependence of the output power of the pristine N2 fiber.

Fig. 5. Output power and STD as functions of pump power for the pristine N2 fiber.

Fig. 6. Time-domain signal and frequency-domain signal of the pristine N2 fiber at the initial state.

Fig. 7. Evolution of the MI threshold of the pristine N2 fiber.

Fig. 8. Relative transmittance at 638 nm of the pristine N2 fiber before and after 300 min pumping, and the calculated inversion along the fiber.

Fig. 9. Time dependence of output power in the H2-loaded N2 fiber and the pristine fiber.

Fig. 10. Output power and STD as functions of pump power for the H2-loaded N2 fiber.

Fig. 11. Time-domain signal and frequency-domain signal of the H2-loaded N2 fiber at the initial state.

Fig. 12. Relative transmittance at 638 nm of the pristine N2 fiber and the H2-loaded N2 fiber after 300 min pumping.

Fig. 13. Schematic representation of H2 cracking NBOHC and AlOHC.