Narrow–linewidth tunable laser source for long-wavelength optical coherence tomography at 1700 nm Olga Szewczyk,, Zbigniew Łaszczych and Grzegorz Soboń EPJ Web Conf., 309 (2024) 07012 Published online: 31 October 2024 DOI: 10.1051/epjconf/202430907012