OPTICAL COHERENCE IN SEMICONDUCTORS - STRONG EMISSION MEDIATED BY NONDEGENERATE INTERACTIONS

The presence of interactions between carriers in differing states, non degenerate interactions, is experimentally demonstrated to result in s trong, new contributions to the optical coherent response of semicondu ctors. These interactions are manifest in a new, state-selective, two- pulse four-wave-mixing technique as emission from a stale that is exci ted by only one pulse. The emission arises due to interactions with an other state that is excited by both pulses. These interactions are obs erved between the Is exciton and continuum states and also between dis tinct magnetoexciton states. The resulting contributions must be inclu ded to properly understand the coherent response.