April 2016
Spotlight Summary by James R. Taylor
Versatile and widely tunable mid-infrared erbium doped ZBLAN fiber laser
This simple CW fiber laser using a commercially available erbium doped ZBLAN fiber allows over 450 nm of narrow-line, tunable radiation centered around 3500 nm using a dual wavelength pump technique, providing a spectral brightness of 160 mW/nm, with the authors alluding to power scaling and average output powers well above the 1.45 W demonstrated. With interest in mid-infrared sources ever increasing to meet the diverse application demands in defense, materials processing, spectroscopy and the biomedical arena, a specific target area is the 3-4 μm region where there are strong resonances of the C-H covalent bond, and sources can be used for organic species detection or polymer processing. The dual pumping technique of combining 980 nm laser diode and 1973 nm Tm fiber lasers, previously introduced by the authors, allows relatively efficient (27% slope efficiency) four-level laser operation of the broad 3.5 μm transition in Er:ZBLAN, in a very simple lens coupled linear cavity terminated with a diffraction grating, that permitted tunability from about 3330 nm to 3780 nm, the longest wavelength achieved with a fiber laser operating at room temperature. The authors also postulate that with increased pump power at 1973 nm this range can be extended by about 15%. Simultaneous lasing at 2.8 μm was also demonstrated, although at substantially reduced power levels, while the 2.8 μm transition can lase solely with the simple expedient of turning off the 1973 nm pump. With increased power of the Tm pump to about 6 W, 100 mW laser output under tunable operation at 3550 nm was achieved. However, fiber core damage occurred, but this should be overcome through end-capping which has been demonstrated by others using this laser pump scheme.
With the proposed power scaling and the potential for improved system slope efficiency, this simple laser system provides a powerful tool in this restricted mid-infrared window.
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With the proposed power scaling and the potential for improved system slope efficiency, this simple laser system provides a powerful tool in this restricted mid-infrared window.
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Article Information
Versatile and widely tunable mid-infrared erbium doped ZBLAN fiber laser
Ori Henderson-Sapir, Stuart D. Jackson, and David J. Ottaway
Opt. Lett. 41(7) 1676-1679 (2016) View: Abstract | HTML | PDF