The dominant mode of a diode laser with optical feedback from an external reflector has usually been assumed to be the external cavity mode with the lowest threshold gain. However, for weak-to-moderate feedback it was shown experimentally1 and in recent numerical simulations2 that the laser predominantly oscillates in the mode with the lowest linewidth. We present measurements of the mode hopping behavior which show the relative stability of the different modes and demonstrate a drastic increase in stability for increasing feedback. A simple theory is outlined which quantitatively explains the observed behavior.
© 1990 Optical Society of AmericaPDF Article