Ultra-narrow linewidth laser across the C-band using polarization-controlled dual-cavity feedback

TY - JOUR

T1 - Ultra-narrow linewidth laser across the C-band using polarization-controlled dual-cavity feedback

AU - Surrow, Jeppe H.

AU - Thomsen, Simon T.

AU - Kumar, Rakesh R.

AU - Far Brusatori, Mónica

AU - Paula Montes, Maria

AU - Palsole, Ahan S.

AU - Hoede, Chris

AU - Klein, Holger N.

AU - Volet, Nicolas

N1 - Publisher Copyright: © 2025 Optica Publishing Group under the terms of the Optica.

PY - 2025/3/6

Y1 - 2025/3/6

N2 - A standard method to reduce the linewidth of semiconductor lasers involves the use of external optical feedback (EOF). However, feedback powers less than 1 % usually trigger coherence collapse (CC), leading to chaotic laser dynamics and linewidth broadening. This paper explores a method to mitigate CC through precise tuning of the feedback polarization depending on the feedback power. We report a semiconductor laser with a sub-100 Hz intrinsic linewidth, achieved via EOF. The laser features a U-shaped cavity with two sampled grating distributed Bragg reflectors (SG-DBRs), enabling broad tunability across a 42 nm wavelength range (1513–1555 nm). By injecting optical feedback into both sides of the laser cavity via an external fiber-based cavity, we reduce the intrinsic linewidth by more than three orders of magnitude, from MHz to sub-kHz across the laser’s tuning range. By dynamically tuning the polarization, we demonstrate sub-100 Hz intrinsic linewidths at feedback powers up to 10 %, marking an improvement over prior studies where CC limited performance.

AB - A standard method to reduce the linewidth of semiconductor lasers involves the use of external optical feedback (EOF). However, feedback powers less than 1 % usually trigger coherence collapse (CC), leading to chaotic laser dynamics and linewidth broadening. This paper explores a method to mitigate CC through precise tuning of the feedback polarization depending on the feedback power. We report a semiconductor laser with a sub-100 Hz intrinsic linewidth, achieved via EOF. The laser features a U-shaped cavity with two sampled grating distributed Bragg reflectors (SG-DBRs), enabling broad tunability across a 42 nm wavelength range (1513–1555 nm). By injecting optical feedback into both sides of the laser cavity via an external fiber-based cavity, we reduce the intrinsic linewidth by more than three orders of magnitude, from MHz to sub-kHz across the laser’s tuning range. By dynamically tuning the polarization, we demonstrate sub-100 Hz intrinsic linewidths at feedback powers up to 10 %, marking an improvement over prior studies where CC limited performance.

U2 - 10.1364/OE.544372

DO - 10.1364/OE.544372

M3 - Journal article

AN - SCOPUS:86000518111

SN - 1094-4087

VL - 33

SP - 11863

EP - 11875

JO - Optics Express

JF - Optics Express

IS - 5

ER -