Drastic emission-spectra changes in a semiconductor laser owing to optical feedback from an optical connector

The time-averaged longitudinal-mode power of a semiconductor laser coupled to a fiber changes drastically when an external force is applied to a multimode fiber terminated with an optical connector. No emission-spectra changes have been observed in the case of a single-mode fiber. This phenomenon is considered to be induced by the wavelength-dependent change of the reflected field speckle intensity coupled into the laser-active region.