Stress modulation and wavelength tuning of an erbium-doped optical fiber laser

The stress on either the erbium-doped or the normal optical fiber inside a cavity can cause output modulation, wavelength tuning in the gain band, and selection of the transition at 1.53 or 1.56 microm in an erbium-doped optical fiber laser. These phenomena are explained with the birefringence of the optical fiber under stress, the polarization properties of the directional coupler loop, and the condition of the laser oscillation. These phenomena may have some practical use in output power control, wavelength tuning, and sensors.