Compact single-end pumped Brillouin random fiber laser with enhanced distributed feedback
Yanping Xu, Ping Lü, Xiaoyi Bao
Abstract
A compact sub-kilohertz linewidth Brillouin random fiber laser (BRFL) based on a linear cavity scheme with single-end pumping and enhanced distributed Rayleigh feedback from fiber random gratings (FRGs) is proposed and demonstrated. The improved FRGs with low transmission loss make the single-end pumped linear cavity configuration achievable without sacrificing the lasing capability, which contributes to a more compact setup for easy integration and packaging. The enhanced Rayleigh feedback from the FRG enables a high-efficiency random lasing resonance of the Stokes wave via stimulated Brillouin scattering in the lasing cavity. More importantly, the single-end pumped scheme, unlike the previously reported bi-directionally pumped BRFL, significantly alleviates the lasing instabilities and noises induced by the counter-propagating laser beams through the Brillouin-active medium, thus exhibiting lower lasing noises. Single-longitudinal-mode operation of the proposed random laser is realized with a narrow linewidth of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>∼</mml:mo> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>0.97</mml:mn> </mml:mrow> <mml:mspace width="thickmathspace"/> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">k</mml:mi> <mml:mi mathvariant="normal">H</mml:mi> <mml:mi mathvariant="normal">z</mml:mi> </mml:mrow> </mml:mrow> </mml:math> .