John J Klima

US Patent:

20090232518, Sep 17, 2009

Filed:

Apr 23, 2009

Appl. No.:

12/428935

Inventors:

John W. Caton - Doylestown PA, US
Joseph Hober - Southampton PA, US
John Klima - Perkasie PA, US
Gustav Witzel - Warminster PA, US

Assignee:

EMCORE CORPORATION - Albuquerque NM

International Classification:

H04B 10/04

US Classification:

398193

Abstract:

An optical transmitter for generating a modulated optical signal to be transmitted over fiber optical link. The transmitter includes: an optical source for producing an optical signal; an optically linearized modulator (OLM) as external modulator for modulating the optical signal produced by the optical source with an information carrying signal. The external modulator includes a first input port for receiving a first DC bias signal, and a second input port for receiving a second DC bias signal. The optical transmitter further includes a pilot tone generator for generating a first pilot signal to be applied to the first input port and a second pilot signal to be applied to the second input port. The first and second pilot signals are capable of producing distortion products in the modulated optical signal. A differential modulation signal is imposed onto either the first pilot signal or the second pilot signal so as to generate a first control signal that alternately adjusts the first DC bias signal and the second DC bias signal in order to minimize the distortion products. The optical transmitter may include a digital based control system that is adapted to reduce composite even and odd order distortions in the OLM.