Optical coherent receiver having an optical hybrid configuration with reduced phase error
An optical coherent receiver includes a 90-degree optical hybrid configured to receive an input signal and a reference signal, and mix the input signal with four quadrature states associated with the reference signal to generate four output signals. The 90-degree optical hybrid includes a plurality of 3-dB couplers; and a plurality of optical waveguides, wherein each optical waveguide of the plurality of optical waveguides couples two respective 3-dB couplers of the plurality of 3-dB couplers, and wherein each optical waveguide of the plurality of optical waveguides has a same optical path length. Each optical waveguide of the plurality of optical waveguides is dimensioned according to a figure of merit (FoM) to reduce a phase error.
1 . A device, comprising:
a plurality of inputs configured to receive an input signal and a reference signal;
a plurality of optical components configured to mix the input signal with the reference signal; and
a plurality of optical waveguides,
wherein an optical waveguide of the plurality of optical waveguides couples two respective optical components of the plurality of optical components,
wherein a set of the plurality of optical waveguides have a same optical path length, and
wherein the plurality of optical waveguides are configured to reduce a phase error.
2 . The device of claim 1 , wherein the plurality of optical waveguides are configured based on a figure of merit (FoM) to reduce the phase error.
3 . The device of claim 2 , wherein the FoM is determined based on a variation in an effective refractive index of a waveguide transverse mode of an optical waveguide of the plurality of optical waveguides and a width variation of a width of the optical waveguide.
4 . The device of claim 1 , wherein the plurality of inputs are associated with a 90-degree optical hybrid.
5 . The device of claim 1 , wherein the plurality of optical waveguides accumulate a same phase.
6 . The device of claim 1 , wherein the plurality of optical waveguides comprise one or more bend sections.
7 . The device of claim 6 , wherein the one or more bend sections are configured to reduce the phase error based on a curvature function that is associated with suppressing an excitation of light to a higher order transverse electric (TE) mode.
8 . The device of claim 1 , wherein the plurality of optical waveguides couple a plurality of couplers,
wherein a first coupler of the plurality of couplers is configured to receive the input signal and generate a first pair of output signals, and
wherein a second coupler of the plurality of couplers is configured to receive the reference signal and generate a second pair of output signals.
9 . The device of claim 1 , wherein the plurality of optical waveguides have an average width that is configured such that a waveguide sensitivity to a figure of merit (FoM) is reduced.
10 . The device of claim 1 , wherein the plurality of optical waveguides have an average width that is configured such that a phase error sensitivity is reduced.
11 . The device of claim 1 , wherein the plurality of optical waveguides comprise a ridge and a shoulder that extends laterally from the ridge.
12 . The device of claim 1 , wherein the plurality of optical waveguides comprise at least one tapered portion having a tapered length configured to minimize insertion loss.
13 . An optical device, comprising:
a first input configured to receive an input signal;
a second input configured to receive a reference signal;
a plurality of optical components configured to mix the input signal with the reference signal; and
a plurality of optical waveguides,
wherein an optical waveguide of the plurality of optical waveguides couples two respective optical components of the plurality of optical components,
wherein a set of the plurality of optical waveguides have a same optical path length, and
wherein the plurality of optical waveguides are configured to reduce a phase error.
14 . The optical device of claim 13 , wherein the plurality of optical waveguides comprise one or more bend sections.
15 . The optical device of claim 14 , wherein the one or more bend sections are configured to reduce the phase error based on a curvature function that is associated with suppressing an excitation of light to a higher order transverse electric (TE) mode.
16 . The optical device of claim 13 , wherein the plurality of optical waveguides are configured based on a figure of merit (FoM) to reduce the phase error.
17 . The optical device of claim 16 , wherein the FoM is determined based on a variation in an effective refractive index of a waveguide transverse mode of an optical waveguide of the plurality of optical waveguides and a width variation of a width of the optical waveguide.
18 . The optical device of claim 16 , wherein the FoM is defined by:
FoM
=
dneff
dw
L
,
wherein dneff denotes a variation in an effective refractive index of a waveguide transverse mode of an optical waveguide of the plurality of waveguides, L denotes a total length of the optical waveguide, and dw denotes a width variation of a width of the optical waveguide.
19 . The optical device of claim 13 , wherein the plurality of optical waveguides accumulate a same phase.
20 . The optical device of claim 13 , wherein the plurality of optical waveguides comprise a ridge and a shoulder that extends laterally from the ridge.