Abstract

We experimentally demonstrate a Brillouin fiber laser (BFL) with a low threshold and narrow linewidth at 2 $\mu$ m employing a chalcogenide As $_{2}$ S $_{3}$ fiber as the Brillouin gain fiber. The As $_{2}$ S $_{3}$ fiber exhibits a Brillouin gain coefficient of 1.76 $\times 10^{-9}$ m/W at 2 $\mu$ m, which is two orders of magnitude higher than that of the silica fiber, together with a Brillouin frequency shift of 6.308 GHz and a gain linewidth of 10.2 MHz. By theoretically optimizing the fiber length adopted in the Brillouin ring cavity, a 3-m-long segment of the As $_{2}$ S $_{3}$ fiber is used to realize a BFL with excellent performance in terms of laser power threshold and linewidth. The BFL shows a total cavity loss of 6.18 dB, corresponding to a cavity feedback parameter of 24.1 $\%$ . The lowest laser power threshold of 39 mW and narrowest laser linewidth of $\sim$ 619 Hz so far, to the best of our knowledge, are simultaneously achieved for the BFL at 2 $\mu$ m. These results benefit from not only the extremely high Brillouin gain coefficient and small effective mode field area of the As $_{2}$ S $_{3}$ fiber but also a suitable Brillouin gain fiber length and low cavity loss of the BFL. The relative intensity noise and temporal stability of the BFL are also investigated. Such a low-threshold and sub-kHz-linewidth laser will facilitate the development of practical applications such as gas sensing and coherent LIDAR in the 2 $\mu$ m spectral range.

Low-threshold Brillouin laser at 2  μm based on suspended-core chalcogenide fiber

Kai Hu, Irina V. Kabakova, Thomas F. S. Büttner, Simon Lefrancois, Darren D. Hudson, Sailing He, and Benjamin J. Eggleton
Opt. Lett. 39(16) 4651-4654 (2014)

Linewidth-narrowing and intensity noise reduction of the 2nd order Stokes component of a low threshold Brillouin laser made of Ge₁₀As₂₂Se₆₈ chalcogenide fiber

Kenny Hey Tow, Yohann Léguillon, Schadrac Fresnel, Pascal Besnard, Laurent Brilland, David Méchin, Denis Trégoat, Johann Troles, and Perrine Toupin.
Opt. Express 20(26) B104-B109 (2012)

Microwave photonic filter with a sub-kHz bandwidth based on a double ring Brillouin fiber laser

Linyi Wang, Yi Liu, Yajun You, Wenjun He, Xin Xu, Liuyan Feng, Wenping Geng, and Xiujian Chou
Opt. Lett. 47(16) 4143-4146 (2022)

Stabilized single-frequency sub-kHz linewidth Brillouin fiber laser cavity operating at 1 µm

Moise Deroh, Erwan Lucas, Kamal Hammani, Guy Millot, and Bertrand Kibler
Appl. Opt. 62(30) 8109-8114 (2023)

Narrow linewidth parity-time symmetric Brillouin fiber laser based on a dual-polarization cavity with a single micro-ring resonator

Yi Liu, Linyi Wang, Xin Xu, Kai Jiang, Yajun You, Wenjun He, Xuefeng Han, Jiaxin Hou, and Xiujian Chou
Opt. Express 30(25) 44545-44555 (2022)