Dual wavelength pumping scheme for directly diode-pumped 75X-nm fiber lasers

• Published in: Journal of lightwave technology 2023-11, Vol.41 (22), p.1-9
• Main Authors: Li, Wensong, Wu, Yulun, Xu, Shihang, Wang, Peng, Chen, Yuan, Piatkowski, Dawid
• Format: Article
• Language: English
• Subjects: Aluminum fluorides; Barium fluorides; blue-diode pumping; deep red lasers; Diodes; Dual wavelength pumping; Fiber lasers; Holmium; holmium lasers; Lanthanum fluorides; Laser excitation; Laser pumping; Laser theory; Laser transitions; Lasers; optical fiber lasers; Pump lasers; Rare earth elements; Semiconductor lasers; Wavelengths
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2023.3297272

For decades, researchers have been interested in developing efficient rare-earth-doped laser sources using dual-wavelength pumping. However, dual-wavelength pumping of rare-earth-doped lasers and amplifiers are currently restricted to pump wavelengths longer than the visible. Extending the use of dual-wavelength pumping for directly diode-pumped rare-earth-doped lasers is of great importance for both academic and practical purposes. We have developed the first blue dual-wavelength pumping of Holmium-doped ZrF 4 -BaF 2 -LaF 3 -AlF 3 -NaF (Ho:ZBLAN) fiber lasers operating at 75X nm. A dual-wavelength pumping method was proposed by pumping two separate wavelengths of 449 and 442 nm into a Ho:ZBLAN fiber to populate the upper laser state 5 F 4 + 5 S 2 and depopulate the lower laser state 5 I 7 , respectively. The influence of the 449 and/or 442 nm pumping schemes on the efficiency and threshold of the 75X nm laser was studied by varying the active fiber length. For dual-wavelength pumping with blue laser diodes, a shorter fiber and a lower 449 nm pump power are favoured. Our approach expands the applicability of dual-wavelength pumping to visible laser systems with energy-level structures consisting of long-lived lower-level bottlenecks.