Nonring travelling-wave laser

A travelling-wave laser with a linear cavity configuration was proposed and constructed. The travelling-wave operation was ensured by the orthogonality of the polarisation states of the counterpropagating waves in the active medium. A fibre variant was used to achieve lasing in the range 1.559 — 1.564 μm. Wavelength tuning was performed by a fibre polarisation controller. The measured lasing linewidth was less than 15 MHz and the output power was up to 18 mW.