U.S. patent application number 15/498274 was filed with the patent office on 2018-11-01 for thermo-optic phase shifter for semiconductor optical waveguide.
The applicant listed for this patent is Cisco Technology, Inc.. Invention is credited to Donald ADAMS, Sean P. ANDERSON.
Application Number | 20180314082 15/498274 |
Document ID | / |
Family ID | 62090062 |
Filed Date | 2018-11-01 |
United States Patent
Application |
20180314082 |
Kind Code |
A1 |
ANDERSON; Sean P. ; et
al. |
November 1, 2018 |
THERMO-OPTIC PHASE SHIFTER FOR SEMICONDUCTOR OPTICAL WAVEGUIDE
Abstract
Embodiments include a method and associated apparatuses for
phase-shifting an optical signal. The method comprises receiving,
at a first end of an optical waveguide formed in a semiconductor
layer and extending along a first axis, an optical signal having a
first phase. The method further comprises transmitting, at a second
end of the optical waveguide opposite the first end, a modified
optical signal having a second phase different than the first
phase. Transmitting a modified optical signal comprises applying a
voltage signal between a first contact region and a second contact
region formed in the semiconductor layer apart from the first axis.
Applying a voltage signal causes an electrical current to be
conducted along a dimension of the optical waveguide. The
electrical current causes resistive heating of the optical
waveguide and a desired phase shift between the first phase and the
second phase.
Inventors: |
ANDERSON; Sean P.;
(Macungie, PA) ; ADAMS; Donald; (Rochester,
NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Cisco Technology, Inc. |
San Jose |
CA |
US |
|
|
Family ID: |
62090062 |
Appl. No.: |
15/498274 |
Filed: |
April 26, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02F 2202/10 20130101;
G02F 1/0147 20130101; G02F 1/2257 20130101; G02F 1/011 20130101;
G02F 2201/12 20130101; G02F 2201/066 20130101 |
International
Class: |
G02F 1/01 20060101
G02F001/01 |
Claims
1. An apparatus comprising: an optical waveguide formed in a
semiconductor layer; a first contact region formed in the
semiconductor layer and intersecting the optical waveguide; and a
first optical transition region that extends between the optical
waveguide and the first contact region, wherein the first contact
region is electrically coupled with the first optical transition
region and configured to conduct electrical current through the
optical waveguide along at least a first dimension of the optical
waveguide to apply resistive heating to the optical waveguide.
2. The apparatus of claim 1, wherein the optical waveguide extends
in the semiconductor layer along a first axis, and wherein the
first contact region extends in the semiconductor layer along a
second axis that is substantially perpendicular to the first
axis.
3. The apparatus of claim 2, wherein the first optical transition
region defines a linear taper between the optical waveguide and the
first contact region.
4. The apparatus of claim 2, wherein the first optical transition
region defines a curved taper between the optical waveguide and the
first contact region.
5. The apparatus of claim 4, wherein the first optical transition
region comprises a first ellipse overlapping the optical waveguide,
wherein the first ellipse has a major axis aligned with the first
axis, and a minor axis aligned with the second axis.
6. The apparatus of claim 5, wherein a ratio of the major axis to
the minor axis is approximately 4:1.
7. The apparatus of claim 1, wherein the first contact region has a
first doping level that is greater than a second doping level of
the optical waveguide.
8. The apparatus of claim 7, wherein the first contact region is
coupled with a first metal contact.
9. The apparatus of claim 1, wherein electrical current is
conducted across a width of the optical waveguide.
10. The apparatus of claim 1, further comprising: a second contact
region formed in the semiconductor layer and intersecting the
optical waveguide; and a second optical transition region that
extends between the optical waveguide and the second contact
region, wherein applying a voltage signal between the first contact
region and the second contact region causes an electrical current
to be conducted along a length of the optical waveguide.
11. The apparatus of claim 10, wherein the length of the optical
waveguide is selected to provide a desired resistance for the
resistive heating.
12. The apparatus of claim 1, further comprising: a substrate
layer; and a dielectric layer having at least partially disposed
between the semiconductor layer and the substrate, wherein the
substrate layer defines a removed region that overlaps with at
least one of the optical waveguide, the first contact region, and
the first optical transition region.
13. An apparatus comprising: an optical waveguide formed in a
semiconductor layer and extending along a first axis, the optical
waveguide having a first doping level; and a first contact region
and a second contact region formed in the semiconductor layer apart
from the first axis, wherein the first contact region and the
second contact region each have a corresponding second doping level
that is greater than the first doping level, wherein an electrical
current is conducted through the optical waveguide along at least a
first dimension of the optical waveguide responsive to a voltage
signal applied between the first contact region and the second
contact region, and wherein resistive heating of the optical
waveguide is provided by the electrical current.
14. The apparatus of claim 13, wherein the optical waveguide
defines a first optical transition region extending away from the
first axis, and wherein the first contact region is electrically
coupled with the first optical transition region.
15. The apparatus of claim 14, wherein the second contact region is
electrically coupled with the first optical transition region.
16. The apparatus of claim 13, wherein each of the first contact
region and the second contact region extends along a respective
second axis that is substantially perpendicular to the first
axis.
17. A method comprising: receiving, at a first end of an optical
waveguide formed in a semiconductor layer and extending along a
first axis, an optical signal having a first phase; and
transmitting, at a second end of the optical waveguide opposite the
first end, a modified optical signal having a second phase
different than the first phase, wherein transmitting a modified
optical signal comprises: applying a voltage signal between a first
contact region and a second contact region formed in the
semiconductor layer apart from the first axis, wherein applying a
voltage signal causes an electrical current to be conducted through
the optical waveguide along at least a first dimension of the
optical waveguide, wherein the electrical current causes resistive
heating of the optical waveguide and a desired phase shift between
the first phase and the second phase.
18. The method of claim 17, wherein the optical waveguide defines a
first optical transition region extending away from the first axis,
and wherein the first contact region is electrically coupled with
the first optical transition region.
19. The method of claim 18, wherein the second contact region is
electrically coupled with the first optical transition region.
20. The method of claim 17, wherein each of the first contact
region and the second contact region extends along a respective
second axis that is substantially perpendicular to the first axis.
Description
TECHNICAL FIELD
[0001] Embodiments presented in this disclosure generally relate to
photonics, and more specifically, a thermo-optic phase shifter
formed in a same semiconductor layer as an optical waveguide.
BACKGROUND
[0002] In photonics circuitry, thermo-optic phase shifters are
often used as optical bias or tuning elements, such as in
modulators or in tunable filters. Generally, an improved efficiency
of thermo-optic phase shifters can be desirable for producing
smaller and/or low-power optical devices, as well as for providing
a greater tuning range within a given power budget.
[0003] One technique for improving the efficiency of a thermo-optic
phase shifter includes placement of a distinct heating element in
close proximity to the optical waveguide, which reduces an amount
of heat that is coupled into other nearby elements, such as a
substrate. However, the close proximity of the heating element
tends to increase an optical insertion loss. Another technique for
improving the efficiency of the thermo-optic phase shifter includes
thermally isolating the heating element and/or optical waveguide
from other elements (e.g., the substrate) using air trenches or
other thermally insulative material(s).
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] So that the manner in which the above-recited features of
the present disclosure can be understood in detail, a more
particular description of the disclosure, briefly summarized above,
may be had by reference to embodiments, some of which are
illustrated in the appended drawings. It is to be noted, however,
that the appended drawings illustrate only typical embodiments of
this disclosure and are therefore not to be considered limiting of
its scope, for the disclosure may admit to other equally effective
embodiments.
[0005] FIG. 1 illustrates an exemplary apparatus for conducting
electrical current along a width of an optical waveguide, according
to one embodiment.
[0006] FIG. 2 illustrates a major axis and a minor axis of an
elliptical optical transition region, according to one
embodiment.
[0007] FIG. 3 illustrates an exemplary optical transition region
defining a linear taper, according to one embodiment.
[0008] FIG. 4 illustrates an exemplary doping profile for a
thermo-optic phase shifter, according to one embodiment.
[0009] FIG. 5 illustrates an exemplary apparatus for conducting
electrical current along a length of an optical waveguide,
according to one embodiment.
[0010] FIG. 6 illustrates a plurality of layers including a
thermo-optic phase shifter in a semiconductor layer, according to
one embodiment.
[0011] FIG. 7 illustrates a plurality of layers having a region
removed from a substrate layer, according to one embodiment.
[0012] FIG. 8 illustrates an exemplary method of phase-shifting an
optical signal, according to one embodiment.
[0013] To facilitate understanding, identical reference numerals
have been used, where possible, to designate identical elements
that are common to the figures. It is contemplated that elements
disclosed in one embodiment may be beneficially utilized on other
embodiments without specific recitation.
DESCRIPTION OF EXAMPLE EMBODIMENTS
Overview
[0014] One embodiment presented in this disclosure is an apparatus
comprising an optical waveguide formed in a semiconductor layer, a
first contact region formed in the semiconductor layer and
intersecting the optical waveguide, and a first optical transition
region that extends between the optical waveguide and the first
contact region. The first contact region is electrically coupled
with the first optical transition region and is configured to
conduct electrical current along a dimension of the optical
waveguide to apply resistive heating to the optical waveguide.
[0015] Another embodiment is an apparatus comprising an optical
waveguide formed in a semiconductor layer and extending along a
first axis, the optical waveguide having a first doping level. The
apparatus further comprises a first contact region and a second
contact region formed in the semiconductor layer apart from the
first axis, wherein the first contact region and the second contact
region each have a corresponding second doping level that is
greater than the first doping level. An electrical current is
conducted along a dimension of the optical waveguide responsive to
a voltage signal applied between the first contact region and the
second contact region, and resistive heating of the optical
waveguide is provided by the electrical current.
[0016] Another embodiment is a method comprising receiving, at a
first end of an optical waveguide formed in a semiconductor layer
and extending along a first axis, an optical signal having a first
phase. The method further comprises transmitting, at a second end
of the optical waveguide opposite the first end, a modified optical
signal having a second phase different than the first phase.
Transmitting a modified optical signal comprises applying a voltage
signal between a first contact region and a second contact region
formed in the semiconductor layer apart from the first axis.
Applying a voltage signal causes an electrical current to be
conducted along a dimension of the optical waveguide, and the
electrical current causes resistive heating of the optical
waveguide and a desired phase shift between the first phase and the
second phase.
Example Embodiments
[0017] Embodiments of the disclosure are generally directed to
implementations of a thermo-optic phase shifter apparatus formed in
a same semiconductor layer as an optical waveguide. In some
embodiments, at least a first contact region is formed in the
semiconductor layer and is configured to conduct electrical current
along a dimension of the optical waveguide to apply resistive
heating to the optical waveguide. The dimension may be a width or a
length of the optical waveguide. In this way, the optical waveguide
itself may be operated as a resistive heating element, such that
the apparatus need not include a separate heating element.
[0018] In some embodiments, the apparatus comprises at least a
first optical transition region that extends between the optical
waveguide and the first contact region. The first optical
transition region has a shape and size that are selected to
mitigate an optical loss that might normally occur due to the
intersection of the first contact region with the optical
waveguide. In some embodiments, the first optical transition region
defines a linear taper between the optical waveguide and the first
contact region. In other embodiments, the first optical transition
region defines a curved taper between the optical waveguide and the
first contact region. For example, the first optical transition
region may be an ellipse that overlaps the optical waveguide, where
a major axis of the ellipse is aligned with a longitudinal axis of
the waveguide, and a minor axis of the ellipse is substantially
perpendicular to the longitudinal axis.
[0019] In some embodiments, the first contact region has a first
doping level that is greater than a second doping level of the
optical waveguide. In one embodiment, the first optical transition
region also has the second doping level. In this way, the optical
waveguide and/or the first optical transition region may have a
greater resistance than in the first contact region, so that the
electrical current tends to concentrate heating at the optical mode
and minimizes heat lost to other portions of the photonics
platform.
[0020] FIG. 1 illustrates an exemplary apparatus 100 for conducting
electrical current along a width of an optical waveguide, according
to one embodiment. In some embodiments, the apparatus 100 is formed
within a single semiconductor layer, such as within a silicon layer
of a silicon-on-insulator (SOI)-based photonics platform comprising
a plurality of optical components. Implementations using suitable
alternate semiconductor material(s) are also possible.
[0021] The apparatus 100 comprises an optical waveguide 105 that
extends in the semiconductor layer along a first axis. As shown,
the first axis corresponds to an X-axis. The apparatus 100 further
comprises a contact region 110 formed in the semiconductor layer
and intersecting the optical waveguide 105. In some embodiments,
the contact region 110 extends in the semiconductor layer along a
second axis. In some embodiments, the second axis is substantially
perpendicular to the first axis. As shown, the second axis
corresponds to a Y-axis. However, in other embodiments, the contact
region 110 may intersect the optical waveguide 105 at other
suitable angles. In some embodiments, the contact region 110
extends to both sides (that is, in the positive Y-direction and in
the negative Y-direction) of the optical waveguide 105. In other
embodiments, the contact region 110 extends only to one side of the
optical waveguide 105. Further, while the extent of the contact
region 110 on the first side of the optical waveguide 105 is
depicted as substantially the same as the extent of the contact
region 110 on the second side of the optical waveguide 105, this is
not a requirement.
[0022] As shown, the contact region 110 is connected with two metal
contacts 120-1, 120-2, although other suitable conductive materials
for the contacts 120-1, 120-2 are possible. The contact 120-1 is
disposed to a first side of the optical waveguide 105 and the
contact 120-2 is disposed to an opposing second side of the optical
waveguide. Through the contacts 120-1, 120-2, the contact region
110 is connected with a voltage source 125 that is configured to
apply a voltage signal v across the optical waveguide 105. The
voltage signal v causes an electrical current 135 to pass between
the contacts 120-1, 120-2 and along a dimension of the optical
waveguide 105. As shown, the dimension of the optical waveguide 105
is a width of the optical waveguide 105 that is substantially
aligned with the Y-axis. Due to thermo-electric properties, the
electrical current 135 causes a heating of the optical waveguide
105, such that the apparatus 100 is configured to receive an
optical signal ("Light in") at the optical waveguide 105 having a
first phase .PHI..sub.1 and transmits a modified optical signal
("Light out") having a second phase .PHI..sub.2 different than the
first phase .PHI..sub.1.
[0023] The apparatus 100 further comprises an optical transition
region 115 that extends between the optical waveguide 105 and the
contact region 110. The optical transition region 115 has a shape
and size that are selected to mitigate an optical loss that might
normally occur due to the intersection of the contact region 110
with the optical waveguide 105. For example, the dimensions of the
optical transition region 115 may be selected based on one or more
of the wavelength of the received first optical signal and the
dimensions of the optical waveguide 105 (e.g., a width of the
optical waveguide 105 in the Y-direction, a thickness of the
semiconductor layer in the Z-direction). One or more taper regions
130 are defined by the optical transition region 115 and extend
between the optical waveguide 105 and the contact region 110.
[0024] In other embodiments, the optical transition region 115
(more specifically, the taper region 130) defines a curved taper
between the optical waveguide 105 and the contact region 110. For
example, and as shown in FIGS. 1 and 2, the optical transition
region 115 may be an ellipse 200 that overlaps the optical
waveguide 105. Other shapes of the optical transition region 115
having a curved taper are also possible, such as circular,
semi-circular, semi-elliptical, and so forth. In some cases, the
ellipse 200 is centered over the intersection of the optical
waveguide 105 and the contact region 110. In some embodiments, a
major axis 205 of the ellipse 200 is aligned with the long axis of
the optical waveguide 105 (as shown, along the X-axis), and a minor
axis 210 of the ellipse 200 is aligned with the long axis of the
contact region 110 (as shown, along the Y-axis and substantially
perpendicular to the long axis of the optical waveguide 105). In
one embodiment, a ratio of the major axis 205 to the minor axis 210
is approximately 4:1. For example, for a major axis 205 of 10
microns (.mu.m), the minor axis 210 is approximately 2.5 .mu.m. The
ratio corresponds to a lowest optical loss of the apparatus
100.
[0025] In some embodiments, the optical transition region 115 (more
specifically, the taper region 130) defines a linear taper between
the optical waveguide 105 and the contact region 110. As shown in
FIG. 3, the optical transition region 115 may be an octagon 305
that overlaps the optical waveguide 105. Other shapes of the
optical transition region 115 having a linear taper are also
possible, such as rectangular, diamond, hexagonal, and so forth.
Further, although curved taper and linear tapers are specifically
discussed herein, the taper region 130 may have any other contour
suitable to reduce optical loss caused by the intersection of the
optical waveguide 105 and the contact region 110.
[0026] In some embodiments, the optical waveguide 105, the contact
region 110, and/or the optical transition region 115 may be
monolithically formed, but this is not a requirement. For example,
the optical waveguide 105, the contact region 110, and the optical
transition region 115 may be etched from a single layer of silicon
or other suitable semiconductor material.
[0027] In some embodiments, a heating concentration of the
apparatus 100 may be controlled by dimensioning and/or doping
different portions of the apparatus 100 differently. For example, a
known etching process may be used to perform a partial etch of the
optical transition region 115 and/or the optical waveguide 105 to
provide a smaller electrical cross section and therefore a
relatively greater resistance than other portion(s) of the contact
region 110. In another example, a known doping process may cause
the optical transition region 115 and/or the optical waveguide 105
to have a relatively lesser doping level and therefore a relatively
greater resistance than the other portion(s) of the contact region
110.
[0028] FIG. 4 illustrates an exemplary doping profile 405 for a
thermo-optic phase shifter, according to one embodiment. More
specifically, diagram 400 illustrates a doping profile 405 relative
to the long axis (as shown, aligned in a Y-dimension) of the
contact region 110.
[0029] In plot 405, the optical transition region 115 and optical
waveguide 105 have a first doping level D1, and the portions 410-1,
410-2 of the contact region 110 that are not overlapping from the
optical transition region 115 have a second doping level D2 that is
greater than doping level D1. In this way, the optical transition
region 115 and the optical waveguide 105 may have a relatively
greater resistance than the portions 410-1, 410-2. When electrical
current flows across the contact region 110, the generated heat has
a greater concentration near the optical waveguide 105 due to the
relatively greater resistance.
[0030] In some embodiments, the optical transition region 115
and/or the optical waveguide 105 may be dimensioned differently
than the portions 410-1, 410-2. For example, the optical transition
region 115 and/or the optical waveguide 105 have a smaller
electrical cross section than the portions 410-1, 410-2, which
provides the optical transition region 115 and/or the optical
waveguide 105 with a relatively greater resistance than the
portions 410-1, 410-2. In one embodiment, the optical transition
region 115 and/or the optical waveguide 105 may be partially etched
to have a shorter height (e.g., in the Z-direction) than the
portions 410-1, 410-2. The different dimensioning may be performed
in addition to, or as an alternative to, the different doping
levels discussed above.
[0031] Further, while the different doping levels and/or heights
have been described as two discrete levels or heights, alternate
embodiments may include more than two discrete levels or heights,
and/or one or more portions having a substantially continuous
transition between different levels or different heights (e.g., a
gradient).
[0032] FIG. 5 illustrates an exemplary apparatus 500 for conducting
electrical current along a length of an optical waveguide,
according to one embodiment. The apparatus 500 may be used in
conjunction with other embodiments described herein. The apparatus
500 comprises the optical waveguide 105, a first contact region
110-1 that intersects the optical waveguide 105 at a first
intersection, and a second contact region 110-2 that intersects the
optical waveguide 105 at a second intersection.
[0033] The contact region 110-1 is connected with a first contact
120-1, and the second contact region 110-2 is connected with a
second contact 120-2. The contact 120-1 is disposed to a first side
of the optical waveguide 105 (in the positive Y-direction) and the
contact 120-2 is also disposed to the first side of the optical
waveguide 105. Alternatively, the contacts 120-1, 120-2 may be
disposed on opposing sides of the optical waveguide 120. The
contact regions 110-1, 110-2 may have substantially the same
material composition, dimensioning, and/or orientation relative to
the optical waveguide 105, but this is not a requirement. For
example, the extent of the contact region 110-1 on the first side
of the optical waveguide 105 is depicted as being substantially the
same as the extent of the contact region 110-2 on the first
side.
[0034] The voltage source 125 is configured to apply a voltage
signal across the optical waveguide 105 though the contact regions
110-1, 110-2. The applied voltage signal causes an electrical
current 135 to pass between the contacts 120-1, 120-2 and along a
dimension of the optical waveguide 105. As shown, the dimension of
the optical waveguide 105 is a length of the optical waveguide 105
that is substantially aligned with the X-axis. Due to
thermo-electric properties, the electrical current 135 causes a
heating of the optical waveguide 105, such that the apparatus 100
is configured to receive an optical signal ("Light in") at the
optical waveguide 105 having a first phase .PHI..sub.1 and
transmits a modified optical signal ("Light out") having a second
phase .PHI..sub.2 different than the first phase .PHI..sub.1.
[0035] The apparatus 500 further comprises a first optical
transition region 115-1 that extends between the optical waveguide
105 and the first contact region 110-1 near the first intersection,
and a second optical transition region 115-2 that extends between
the optical waveguide 105 and the second contact region 110-2 near
the second intersection. As shown, the first optical transition
region 115-1 and the second optical transition region 115-2 extend
beyond the corresponding intersection, e.g., to the negative
Y-direction of the optical waveguide 105.
[0036] The first optical transition region 115-1 and second optical
transition region 115-2 each has a shape and size that are selected
to mitigate an optical loss that might normally occur due to the
intersection of the corresponding contact region 110-1, 110-2 with
the optical waveguide 105. For example, the dimensions of each
optical transition region 115-1, 115-2 may be selected based on one
or more of the wavelength of the received first optical signal and
the dimensions of the optical waveguide 105 (e.g., a width of the
optical waveguide 105 in the Y-direction, a thickness of the
semiconductor layer in the Z-direction). The first optical
transition region 115-1 and the second optical transition region
115-2 each include one or more taper regions.
[0037] Consistent with the discussion above, the optical transition
regions 115-1, 115-2, the optical waveguide 105, and/or the contact
regions 110-1, 110-2 may have relative doping levels and/or
dimensioning to provide relative resistance. In this way, resistive
heat generated by the flow of electrical current 135 may have a
greater concentration near the optical waveguide 105. A length L of
the optical waveguide 105 is defined between the first intersection
and the second intersection. In some embodiments, the length L is
selected such that the optical waveguide 105 presents a desired
resistance R.sub.L between the first contact 110-1 and the second
contact 110-2.
[0038] FIG. 6 illustrates a plurality of layers including a
thermo-optic phase shifter in a semiconductor layer, according to
one embodiment. For example, the photonics platform 600 depicted in
FIG. 6 may be a SOI-based photonics platform. The thermo-optic
phase shifter (e.g., an apparatus 100, 500) may be formed in a
semiconductor layer 615 of the photonics platform, according to
techniques discussed above.
[0039] In photonics platform 600, a dielectric layer 610 is
partially disposed between a substrate layer 605 and the
semiconductor layer 615. In an example SOI-based implementation,
the semiconductor layer 615 may be formed of silicon (Si), the
dielectric layer 610 may be formed of silicon dioxide (SiO.sub.2),
and the substrate layer 605 may be formed of silicon. As shown, the
dielectric layer 610 substantially surrounds the semiconductor
layer 615. However, in other embodiments, the dielectric layer 610
is disposed entirely between the substrate layer 605 and the
semiconductor layer 615.
[0040] In FIG. 7, a photonics platform 700 has a removed region 705
from a substrate layer 605. The removed region 705 is generally
overlapping with at least a portion of the semiconductor layer 615.
In some embodiments, the removed region overlaps with at least one
of an optical waveguide, a contact region, and an optical
transition region formed in the semiconductor layer 615.
[0041] The material of the removed region 705 may be removed using
backside etching techniques that are known in the art. In one
example, a deep reactive ion etching or a wet etching may be
performed from a surface 710 of the substrate layer 605. In another
example, a complementary metal-oxide-semiconductor (CMOS) etching
process or a microelectromechanical systems (MEMS) etching process
may be performed from the surface 710. Whatever backside etching
process is used, in some embodiments the removed region 705 extends
from the surface 710 to an opposing surface 715 of the substrate
layer 605.
[0042] Removing material from the removed region 705 minimizes a
primary thermal radiation path from the thermo-optic phase shifter
(in the semiconductor layer 615) to the substrate layer 605.
Minimizing the thermal radiation path improves the efficiency of
the thermo-optic phase shifter, which in some cases can be an
improvement of up to 10 times.
[0043] FIG. 8 illustrates an exemplary method 800 of phase-shifting
an optical signal, according to one embodiment. Method 800 may be
used in conjunction with other embodiments disclosed herein, such
as the apparatus 100 of FIG. 1 or the apparatus 500 of FIG. 5.
[0044] Method 800 begins at block 805, where an optical signal is
received at a first end of an optical waveguide formed in a
semiconductor layer and extending along a first axis. The first
optical signal has a first phase.
[0045] At block 815, a modified optical signal is transmitted at a
second end of the optical waveguide opposite the first end. The
modified optical signal has a second phase different than the first
phase. In some embodiments, transmitting the modified optical
signal comprises applying a voltage signal between a first contact
region and a second contact region that are formed in the
semiconductor layer apart from the first axis. Applying the voltage
signal conducts electrical current along a dimension of the optical
waveguide to cause resistive heating of the optical waveguide. In
some embodiments, the dimension is a width of the optical
waveguide. In other embodiments, the dimension is a length of the
optical waveguide. Method 800 ends following completion of block
815.
[0046] In the preceding, reference is made to embodiments presented
in this disclosure. However, the scope of the present disclosure is
not limited to specific described embodiments. Instead, any
combination of the described features and elements, whether related
to different embodiments or not, is contemplated to implement and
practice contemplated embodiments. Furthermore, although
embodiments disclosed herein may achieve advantages over other
possible solutions or over the prior art, whether or not a
particular advantage is achieved by a given embodiment is not
limiting of the scope of the present disclosure. Thus, the
preceding aspects, features, embodiments, and advantages are merely
illustrative and are not considered elements or limitations of the
appended claims except where explicitly recited in a claim(s).
[0047] In view of the foregoing, the scope of the present
disclosure is determined by the claims that follow.
* * * * *