US 12,323,233 B2
System, apparatus, and architecture for migrating an optical communication network
Xiang Zhou, Sunnyvale, CA (US); Cedric F. Lam, San Jose, CA (US); Ryohei Urata, San Carlos, CA (US); and Hong Liu, Palo Alto, CA (US)
Assigned to Google LLC, Mountain View, CA (US)
Filed by Google LLC, Mountain View, CA (US)
Filed on Mar. 22, 2023, as Appl. No. 18/124,707.
Application 18/124,707 is a continuation of application No. 17/228,098, filed on Apr. 12, 2021, granted, now 11,641,248.
Claims priority of provisional application 63/155,003, filed on Mar. 1, 2021.
Prior Publication US 2023/0224068 A1, Jul. 13, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. H04J 14/06 (2006.01); H04B 10/50 (2013.01); H04B 10/61 (2013.01); H04J 14/02 (2006.01); H04B 10/60 (2013.01)
CPC H04J 14/06 (2013.01) [H04B 10/501 (2013.01); H04B 10/614 (2013.01); H04B 10/6151 (2013.01); H04J 14/0305 (2023.08); H04B 10/50 (2013.01); H04B 10/505 (2013.01); H04B 10/60 (2013.01)] 18 Claims
OG exemplary drawing
 
1. An optical transmission system, comprising:
an optical transmitter configured to generate a four dimensional optical signal, the optical transmitter having:
a laser;
a first Mach-Zehnder modulator optically coupled to the laser;
a second Mach-Zehnder modulator optically coupled to the laser;
a first multiplexer optically coupled directly to the first Mach-Zehnder modulator;
a second multiplexer;
a time delay module optically coupling the second Mach-Zehnder modulator and the second multiplexer; and
a polarization beam combiner coupled to the first and second multiplexers and configured to output an encoded optical signal received from the first and second multiplexers onto an optical fiber; and
a two dimensional coherent optical receiver, comprising:
a polarization beam splitter configured to receive an encoded optical signal and output a first output signal and a second output signal;
a delay unit configured to receive the second output signal and produce a delayed second output signal;
at least one of an optical coupler or a Mach-Zehnder interferometer optically coupled to the polarization beam splitter and the delay unit, the optical coupler or Mach-Zehnder interferometer each having a first input and a second input and a first output, the first input receiving the first output signal and the second input receiving the delayed second output signal, the first output comprising a folded optical signal formed by combining the first output signal and the delayed second output signal, wherein the delayed second output signal is rotated into a polarization space corresponding to the first output signal so that the first output signal and the delayed second output signal are in the same polarization space and wherein the delayed second output signal of the folded optical signal is delayed relative to the first output signal of the folded optical signal; and
a de-multiplexer optically coupled to the at least one of the optical coupler or the Mach-Zehnder interferometer to receive the folded optical signal from the first output of the optical coupler or the Mach-Zehnder interferometer.