Equalizer for optical communication systems

US5378937A · kind A · utility

Assignee

• Alcatel N.V. · NL

Inventors

• Rolf Heidemann · Zöblitz, DE
• Heinz Krimmel · Ditzingen, DE
• Bernhard Junginger · Herrenberg, DE

Key dates

• Filing date: Jun 29, 1992
• Grant date: Jan 3, 1995
• Expiry date: Jun 29, 2012

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04B10/25137
• WIPO field: Telecommunications
• WIPO sector: Electrical engineering

Abstract

To compensate for nonlinear signal distortions in analog optical communication transmission systems, caused by laser chirps and the chromatic dispersion of the optical fiber, an equalizer in the form of an LC component is known, whose capacitance is formed by a variable capacitance diode. However, the known equalizer functions only when the capacitance has the proper polarity, which cannot be predicted because of possible polarity inversion during signal transmission. According to the invention, the variable capacitance diode (C.sub.a) has another variable capacitance diode (C.sub.b), with the opposite polarity, connected in parallel, and is equally biased in the high-resistance direction. By adjusting the bias voltage of both capacitances, it can be achieved that one of the two variable capacitance diodes takes over the equalization function, and the other is practically inoperative. Further developments of this solution concern keeping the frequency response constant during adjustment of the equalization, by means of a capacitance connected in parallel to the variable capacitance diodes (C.sub.a, C.sub.b), and the equalization of large bandwidth signals by an LC chain circuit wit…