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Even-order harmonic cancellation and increased RF gain using dual-output mach-zehnder modulator with two wavelength input

Patent image
NRL

A method and system for processing analog optical signals to produce a single RF output free from even-order harmonic distortion. Two analog optical signals of different wavelengths λ1, λ2 are input into a dual-output Mach-Zehnder modulator (MZM), where one wavelength input is high-biased and one wavelength is low-biased. The complementary high- and low-biased wavelengths are output from each arm of the MZM to a multiplexer, which filters out the unwanted high- or low-biased wavelengths from each MZM arm so that both wavelengths are low-biased or high-biased. The signals are passed to a pair of photodiodes, and the photocurrents from the photodiodes are differenced to produce the final RF output. Because of the complementary phase differences between the two low- or high-biased signals generating the photocurrent, all components of the photocurrent except the fundamental and odd-order harmonics cancel each other, resulting in a high-quality RF output free from harmonic distortion.

Inventors: 
Devgan, Preetpaul S.; Urick, Vincent J.; Williams, Keith J.; Diehl, John F.; Sunderman, Christopher E.
Patent Number: 
Technical domain: 
Communications
FIle Date: 
2010-01-15
Grant Date: 
2012-07-17
Grant time: 
914 days
Grant time percentile rank: 
16
Claim count percentile rank: 
4
Citations percentile rank: 
1
'Cited by' percentile rank: 
1
Assignee: 
US NAVY