Optical transmitter

US5550667A · kind A · utility

Assignee

• Alcatel N.V. · NL

Inventors

• Heinz Krimmel · Ditzingen, DE
• Henning Bulow · Kornwestheim, DE
• Rolf Heidemann · Zöblitz, DE
• Jurgen Otterbach · Stuttgart, DE

Key dates

• Filing date: Aug 18, 1993
• Grant date: Aug 27, 1996
• Expiry date: Aug 18, 2013

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04B10/2537
• WIPO field: Telecommunications
• WIPO sector: Electrical engineering

Abstract

A laser (2) of an optical transmitter (1) for the transmission of an analog broadband signal for CATV in particular, can be amplitude-modulated in two different manners with an intelligence signal (N). Direct modulation can lead to an undesired additional frequency modulation. With indirect modulation by means of an optical intensity modulator (3), Brillouin scattering occurs at powers of approximately 10 mW in an optical fiber of the transmission path connected to the optical transmitter (1). Both modulations lead to distortions of the transmitted signal. In order to avoid the disadvantages of both modulations in a technically simple fashion, the carrier emitted from a laser (2) is indirectly modulated with an intelligence signal (N) and the laser (2) also faintly directly modulated with an energy-dispersing signal (V). The faint direct modulation leads to a constant, limited wave length alteration of the optical signal, such that Brillouin scattering is reduced, simultaneously with the avoidance of dispersion distortions.