High Power Broadband Amplified Spontaneous Emission Source Near 3 m

We report a high power single-end output amplified spontaneous emission (ASE) Ho-doped ZBLAN fiber source near 3 μm. Different from the conventional ASE transitions terminating on ground state where spectra narrowing or essentially unchanging was exhibited at increased pump power, the ASE transition occurred between metastable levels in this case showed distinguished spectrum evolution with increasing pump power, i.e., broadening first then narrowing. In addition, compared with copropagating pumped scheme, better performance was shown under counter-propagating pumped scheme where the broadest spectrum coverage of ~130 nm spanning from ~2845 to ~2975 nm with an full-width at half-maximum (FWHM) bandwidth of ~46 nm and an output power of 43.65 mW was achieved. As further pump power increasing, the reported highest ASE power of 219.76 mW at 3-μm waveband was also achieved at a slope efficiency of 11.11% with a narrowed FWHM bandwidth of ~26 nm and a red-shifted peak wavelength of 2925 nm.