Title :
Generation and cancellation of second-order harmonic distortion in analog optical systems by interferometric FM-AM conversion
Author :
Lidgard, Anne ; Olsson, N.A.
Author_Institution :
AT&T Bell Labs., Murray Hill, NJ, USA
fDate :
7/1/1990 12:00:00 AM
Abstract :
The generation of strong harmonic distortion from interferometric FM-AM conversion in analog lightwave systems is demonstrated both theoretically and experimentally. The effect results from the combined effects of wavelength chirping of the laser coupled with the nonlinear transmission characteristics of a dispersive element in the optical beam path. It is shown that reflections as small as 2-10/sup -4/ will result in second-order distortion as large as -65 dBc. The effect can also be used to cancel any laser- or detector-induced harmonic distortion. In one example, the -36 dBc second-order distortion in a distributed-feedback (DFB) laser is improved to better than -70 dBc.<>
Keywords :
amplitude modulation; distributed feedback lasers; frequency modulation; light interferometry; noise; optical communication equipment; optical dispersion; optical harmonic generation; optical links; optical modulation; analog optical systems; detector-induced harmonic distortion; dispersive element; distributed feedback laser; interferometric FM-AM conversion; laser chirping; laser-induced harmonic distortion; lightwave systems; nonlinear transmission characteristics; optical beam path; reflections; second-order distortion; second-order harmonic distortion; wavelength chirping; Chirp; Dispersion; Harmonic distortion; Laser noise; Laser theory; Optical beams; Optical coupling; Optical distortion; Optical harmonic generation; Optical interferometry;
Journal_Title :
Photonics Technology Letters, IEEE
