US 11,057,114 B2
Optical loopback circuits for transceivers and related methods
Long Chen, Marlboro, NJ (US); and Christopher Doerr, Middleton, NJ (US)
Assigned to Acacia Communications, Inc., Maynard, MA (US)
Filed by Acacia Communications, Inc., Maynard, MA (US)
Filed on Aug. 4, 2016, as Appl. No. 15/228,462.
Prior Publication US 2018/0041282 A1, Feb. 8, 2018
Int. Cl. H04B 10/075 (2013.01); H04B 10/50 (2013.01); H04B 10/40 (2013.01); H04B 10/035 (2013.01)
CPC H04B 10/501 (2013.01) [H04B 10/035 (2013.01); H04B 10/075 (2013.01); H04B 10/40 (2013.01); H04B 10/50 (2013.01); H04B 10/5057 (2013.01)] 15 Claims
OG exemplary drawing
 
1. An apparatus, comprising:
a housing; and
an optical transceiver disposed within the housing, the optical transceiver comprising:
an optical transmitter having output terminals, the optical transmitter being configured to transmit a plurality of symbols through the output terminals, wherein at least one symbol of the plurality of symbols represents a number of bits greater than one;
an optical receiver having an input terminal;
a first optical waveguide and a second optical waveguide; and
an optical loopback circuit coupling a first output terminal of the output terminals of the optical transmitter to the input terminal of the optical receiver, wherein the optical loopback circuit comprises an optical switch,
wherein the first output terminal and a second output terminal of the output terminals are formed using respective output terminals of a Mach-Zehnder optical modulator configured to modulate the plurality of symbols onto an optical signal, and
wherein the first optical waveguide couples the first output terminal of the optical transmitter to the optical switch, and wherein the second optical waveguide couples the second output terminal of the optical transmitter to a fiber output port of the apparatus.