<title>External optical feedback phenomena in semiconductor lasers</title>

Abstract

In optical fibre networks, the semiconductor laser source may be subjected to unavoidable optical feedback from fibre pigtails, fibre connectors and other components, unless expensive optical isolators are used. Therefore, a good understanding of external optical feedback phenomena in semiconductor lasers is required. This paper will review these phenomena, including linewidth narrowing and broadening, mode hopping phenomena and the transition to the so-called coherence-collapse regime. In particular, laser designs with high endurance against optical feedback will be discussed. O-8194-1801-3/951$6.OO SPIE Vol. 2450 / 121 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 05/14/2015 Terms of Use: http://spiedl.org/terms SPIE Vol. 24S0 / 123 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 05/14/2015 Terms of Use: http://spiedl.org/terms 555-564, Apr. 1982 [11] K. Kikuchi and T. Okoshi: Simple formula giving spectrum narrowing ratio of semiconductorlaser output obtained by optical feedback;

Toward a Feedback-Insensitive Semiconductor Laser

“…In the absence of any external disturbance the corresponding relaxation oscillation is damped. When the laser is driven by an outside source, sustained relaxation oscillations may be excited as a first step towards further destabilization and line broadening [8]- [13]. Driving forces could for instance be current modulation or the injection of light from another laser, but also EOF.…”