LONG-TERM STABLE MODE-LOCKING OF A VISIBLE DIODE-LASER WITH PHASE-CONJUGATE FEEDBACK

We present a new method to obtain long-term stable phase-conjugate fee dback (pcf) with a photorefractive crystal for a mode-locked semicondu ctor laser. The phase-conjugate mirror is a barium titanate crystal in a self-pumped internal reflection configuration, and the laser is a v isible, antireflection-coated AlGaInP diode. We describe a new dynamic writing procedure for growth of an index grating in the photorefracti ve crystal that leads to stable pcf and discuss the reasons for this s tability, which is the major advantage of this method over previously reported ones. Using this superior method, we achieve stable mode-lock ed operation of the laser with pulse widths of similar to 30 ps and a timing jitter of less than 2 ps.