Thermal Switching of Lasing Regimes in Heavily Doped Er3+ Fiber Lasers

• Published in: ACS photonics 2018-12, Vol.5 (12), p.5038-5046
• Main Authors: Smirnov, Alexander M, Bazakutsa, Alexey P, Chamorovskiy, Yuri K, Nechepurenko, Igor A, Dorofeenko, Alexander V, Butov, Oleg V
• Format: Article
• Language: English
• ISSN: 2330-4022; 2330-4022
• DOI: 10.1021/acsphotonics.8b01298

A pulsed regime of short-cavity, heavily erbium-doped fiber lasers is of high interest for its possible applications in telecommunications and sensorics. Here, we demonstrate and compare these lasers in two configurations, a distributed feedback laser and a classic Fabry–Perot-type laser. We have managed to create lasers that function stably with cavities as small as 50 mm. Pulse properties such as amplitude, frequency, and duration are in a good agreement with our theoretical analysis, which takes into account spontaneous emission. We report the observation of the thermal switching effect, which consists in the pulsing regime changing to CW upon cooling the laser cavities down to liquid nitrogen temperature. We theoretically show that this effect may be explained by weakening of the up-conversion process responsible for the pulsed regime. The slowing of the up-conversion processes is due to the energy mismatch in this process, which is overcome by interaction with phonons. At low temperatures, the number of phonons decreases and pulsing switches off.