US 12,463,727 B2
Tunable optical filter in coherent optical transmitters
Michael Hubbard, Nepean (CA); Will Leckie, Ottawa (CA); Victor Aldea, Nepean (CA); and Priyanth Mehta, Nepean (CA)
Assigned to Ciena Corporation, Hanover, MD (US)
Filed by Ciena Corporation, Hanover, MD (US)
Filed on Apr. 4, 2022, as Appl. No. 17/712,263.
Prior Publication US 2023/0318712 A1, Oct. 5, 2023
Int. Cl. H04B 10/50 (2013.01); H04B 10/61 (2013.01); H04B 10/079 (2013.01); H04B 10/2507 (2013.01); H04J 14/02 (2006.01)
CPC H04B 10/5051 (2013.01) [H04B 10/615 (2013.01); H04B 10/616 (2013.01); H04B 10/07955 (2013.01); H04B 10/07957 (2013.01); H04B 10/2507 (2013.01); H04B 10/25073 (2013.01); H04B 10/50 (2013.01); H04J 14/02 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A coherent optical transmitter comprising:
a coherent modulator;
a plurality of tunable optical filters, integrated within the coherent optical transmitter, connected to an output of the coherent modulator, wherein each of the plurality of tunable optical filters has a fixed width and a tunable center frequency and wherein the plurality of tunable optical filters are cascaded and configured such that frequency offsets between their tunable center frequencies to create an effective transfer function having a variable width and center frequency; and
one or more photodetectors configured to monitor the plurality of tunable optical filters, wherein the plurality of tunable optical filters are adaptively controlled such that the variable width and the center frequency is based on signal baud or spectral width of a signal from the output determined based on measurements from the one or more photodetectors, such that the effective transfer function suppresses out-of-band noise and an output of the coherent optical transmitter has corresponding noise pedestals removed prior to any multiplexing.