Suppression of some artifacts of modal noise in fiber-optic systems

Abstract

Modal noise, which can cause severe distortion in signals transmitted by fiber optics, is an interference effect that is made more severe by the narrow spectral width of single-mode lasers. The linearity of these devices may be totally obscured after the optical signal has passed through the connectors and fiber lengths of a practical signal system. Dithering the laser's operating point by means of a high-frequency current (>2 GHz) has been found greatly to reduce modal noise.