The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 07, 1998
Filed:
Jan. 16, 1996
John Charles Goodwin, Nepean, CA;
Northern Telecom Limited, Montreal, CA;
Abstract
A method and apparatus for transmitting an analog signal over an optical fiber cable is disclosed. A semiconductor laser provides an optical carrier signal, the laser having the natural linewidth at high power of the same order as the SBS linewidth. The method comprises directly modulating the current of the laser with a dither signal comprising a first component f.sub.C and a second component f.sub.S. Due to the nonlinearity of the 'I-V' characteristic of the laser, a thermal modulation component f.sub.T appears in the active region. This thermal modulation component reshapes the spectrum of the semiconductor laser to increase the threshold of the SBS. As a result, the energy of the signal transmitted over the optical cable may be increased by approximately 16 dB. The first frequency is at least twice the maximum frequency of the analog signal and the second frequency is selected to obtain f.sub.C -f.sub.S =f.sub.T.