CN210375633U - On-chip waveguide loss measuring device - Google Patents
On-chip waveguide loss measuring device Download PDFInfo
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- CN210375633U CN210375633U CN201921373455.2U CN201921373455U CN210375633U CN 210375633 U CN210375633 U CN 210375633U CN 201921373455 U CN201921373455 U CN 201921373455U CN 210375633 U CN210375633 U CN 210375633U
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Abstract
The application provides a waveguide loss measuring device on a silicon substrate. The on-chip waveguide loss measuring device includes: an optical coupler formed in top silicon of a silicon-on-insulator (SOI) substrate; a Fabry-Perot resonant cavity formed in the top silicon, a light incident end of the Fabry-Perot resonant cavity being laterally opposite to a light exit end of the optical coupler; a photodetector formed on the top layer silicon; and a heater formed at a predetermined distance from the Fabry-Perot resonant cavity. By using the on-chip waveguide loss measuring device, the requirement on the alignment precision of the optical fiber and the chip can be effectively reduced, the waveguide loss measuring structure area is reduced, and efficient and quick waveguide loss measurement is realized.
Description
Technical Field
The present application relates to the field of semiconductor technology, and in particular, to a method and an apparatus for measuring waveguide loss on a silicon substrate, and a method for manufacturing the same.
Background
Silicon photonics, which is a new generation technology for optical device development and integration based on silicon and silicon-based substrate materials (e.g., SiGe/Si, SOI, etc.) using existing CMOS processes, combines the characteristics of ultra-large scale, ultra-high precision fabrication of integrated circuit technology with the advantages of photonics technology, ultra-high speed, ultra-low power consumption. Silicon photonics has urgent application requirements in the fields of optical communication and optical interconnection at the present stage, and is a potential technology for realizing on-chip optical interconnection and optical computers in the future.
Although the manufacturing process of the silicon optical chip is compatible with the CMOS process, the packaging and measuring cost of the silicon optical module is difficult to be effectively reduced, which also makes the cost advantage of the silicon optical chip not be fully demonstrated. The transmission loss of a silicon waveguide is one of the important characterizing parameters of a silicon photonics wafer. In the prior art, the waveguide loss is usually measured by a cut-back method.
It should be noted that the above background description is only for the convenience of clear and complete description of the technical solutions of the present application and for the understanding of those skilled in the art. Such solutions are not considered to be known to the person skilled in the art merely because they have been set forth in the background section of the present application.
SUMMERY OF THE UTILITY MODEL
The inventor of the present application finds that when the waveguide loss is measured by using the conventional cut-back method, light needs to be coupled into multiple sections of waveguides with different lengths, and the measurement accuracy is affected by the inconsistency of the performance of the optical fiber/coupler and the inconsistency of the coupling alignment accuracy. In order to realize relatively accurate measurement, waveguide structures with different lengths need to be designed, and a large amount of chip space is occupied; in addition, output light needs to enter an external detector through a coupling structure to measure output power, and measuring errors and cost are further improved.
The embodiment of the application provides an on-chip waveguide loss measuring method, an on-chip waveguide loss measuring device and a manufacturing method thereof, wherein a Fabry-Perot cavity is integrated in the on-chip waveguide loss measuring device, after light enters the Fabry-Perot cavity, a photoelectric detector at the other end of the Fabry-Perot cavity detects output optical signals, a heater adjusts the temperature of the Fabry-Perot cavity, the loss of optical waveguides can be calculated by measuring the output optical signals of the Fabry-Perot cavity at different temperatures, and by using the on-chip waveguide loss measuring device, the requirement on alignment precision of optical fibers and a chip can be effectively reduced, the waveguide loss measuring structure area is reduced, and efficient and rapid waveguide loss measurement is realized.
According to an aspect of an embodiment of the present application, there is provided an on-chip waveguide loss measurement apparatus including:
an optical coupler formed in top silicon of a silicon-on-insulator (SOI) substrate;
a Fabry-Perot resonant cavity formed in the top silicon, a light incident end of the Fabry-Perot resonant cavity being laterally opposite to a light exit end of the optical coupler;
a photodetector formed on the top layer silicon; and
a heater formed at a predetermined distance of the Fabry-Perot resonant cavity.
According to another aspect of the embodiments of the present application, wherein the on-chip waveguide loss measuring device further comprises:
a cover layer covering the optical coupler, the Fabry-Perot resonant cavity, the photodetector, and the heater.
According to another aspect of an embodiment of the present application, wherein the cover layer has an opening, the optical coupler is located below the opening.
According to another aspect of an embodiment of the present application, wherein the optical coupler is an end-face coupler or a grating coupler.
According to another aspect of embodiments herein, wherein the photodetector is a germanium (Ge) detector or a germanium tin (GeSn) detector.
According to another aspect of the embodiments of the present application, there is provided a method for measuring an on-chip waveguide loss by using the apparatus for measuring an on-chip waveguide loss according to any one of the above embodiments, the method comprising:
irradiating light to the optical coupler;
adjusting the bias voltage of the heater, and measuring the photocurrent values output by the photoelectric detector under different bias voltages;
and calculating the loss of the on-chip waveguide according to the power of the photocurrent.
According to another aspect of the embodiments of the present application, there is provided a method of manufacturing an on-chip waveguide loss measurement device, including:
forming an optical coupler in top silicon of a silicon-on-insulator (SOI) substrate;
forming a Fabry-Perot resonant cavity in the top silicon, wherein a light incident end of the Fabry-Perot resonant cavity is transversely opposite to a light emergent end of the optical coupler;
forming a photodetector on the top layer of silicon; and
a heater is formed at a predetermined distance of the Fabry-Perot resonator cavity.
According to another aspect of the embodiments of the present application, wherein the manufacturing method further comprises:
forming a cover layer covering the optical coupler, the Fabry-Perot resonant cavity, the photodetector, and the heater.
According to another aspect of the embodiments of the present application, wherein the method further comprises:
an opening is formed in the cover layer, the optical coupler being located below the opening.
The beneficial effect of this application lies in: the on-chip waveguide loss measuring device is used for measuring waveguide loss, the requirement of alignment precision of optical fibers and chips can be effectively lowered, the structural area of waveguide loss measurement is reduced, and efficient and quick waveguide loss measurement is realized.
Specific embodiments of the present application are disclosed in detail with reference to the following description and drawings, indicating the manner in which the principles of the application may be employed. It should be understood that the embodiments of the present application are not so limited in scope. The embodiments of the application include many variations, modifications and equivalents within the spirit and scope of the appended claims.
Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments, in combination with or instead of the features of the other embodiments.
It should be emphasized that the term "comprises/comprising" when used herein, is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps or components.
Drawings
The accompanying drawings, which are included to provide a further understanding of the embodiments of the application, are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. It is obvious that the drawings in the following description are only some embodiments of the application, and that for a person skilled in the art, other drawings can be derived from them without inventive effort. In the drawings:
fig. 1 is a schematic cross-sectional view of an on-chip waveguide loss measuring device according to embodiment 1 of the present application;
FIG. 2 is a schematic diagram of a method of calculating waveguide loss using the on-chip waveguide loss measurement apparatus 100 of FIG. 1;
fig. 3 is a schematic diagram showing a current value of the photocurrent output from the photodetector 104 as a function of the bias voltage of the heater 105;
fig. 4 is a schematic view of a manufacturing method of an on-chip waveguide loss measuring device according to embodiment 2 of the present application.
Detailed Description
The foregoing and other features of the present application will become apparent from the following description, taken in conjunction with the accompanying drawings. In the description and drawings, particular embodiments of the application are disclosed in detail as being indicative of some of the embodiments in which the principles of the application may be employed, it being understood that the application is not limited to the described embodiments, but, on the contrary, is intended to cover all modifications, variations, and equivalents falling within the scope of the appended claims.
In the description of the embodiments of the present application, for convenience of description, a direction parallel to the surface of the substrate is referred to as "lateral direction", and a direction perpendicular to the surface of the substrate is referred to as "longitudinal direction", wherein "thickness" of each component refers to a dimension of the component in the "longitudinal direction", a direction directed from a buried oxide layer of the substrate toward the top silicon layer in the "longitudinal direction" is referred to as "upper" direction, and a direction opposite to the "upper" direction is referred to as "lower" direction.
Example 1
The embodiment of the application provides an on-chip waveguide loss measuring device.
Fig. 1 is a schematic cross-sectional view of an on-chip waveguide loss measurement device according to embodiment 1 of the present application.
As shown in fig. 1, an on-chip waveguide loss measuring apparatus 1 includes: an optical coupler 102, a Fabry-perot cavity 103, a photodetector 104, and a heater 105.
As shown in fig. 1, an optocoupler 102 is formed in the top silicon 101 of a silicon-on-insulator (SOI) substrate 100; a fabry-perot resonator 103 is formed in the top silicon 101, and a light incident end 1031 of the fabry-perot resonator 103 is laterally opposite to a light emitting end 1022 of the optical coupler; the photodetector 104 is formed on the top silicon 101; the heater 105 is formed at a predetermined distance of the fabry-perot resonator 103.
According to this embodiment, a fabry-perot cavity is integrated in the on-chip waveguide loss 1 measurement apparatus, after light enters the fabry-perot cavity 103 through the optical coupler 102, the photodetector 104 at the other end of the fabry-perot cavity detects an optical signal output from the fabry-perot cavity 103, the heater 105 adjusts the temperature of the fabry-perot cavity, and the loss of the optical waveguide in the top silicon 101 of the silicon-on-insulator (SOI) substrate 100 can be calculated by measuring the output optical signal of the fabry-perot cavity at different temperatures.
In the present embodiment, as shown in fig. 1, a silicon-on-insulator (SOI) substrate 100 may include: a substrate silicon layer 108, a buried oxide layer 106, and a top silicon layer 101. The substrate silicon 108 is made of monocrystalline silicon, the top layer silicon 101 is made of monocrystalline silicon, and the buried oxide layer 106 is made of silicon dioxide.
In this embodiment, the optical coupler 102 may have a light incident end 1021 and a light emitting end 1022. The light incident end 1021 may receive light incident to the optical coupler 102, and the light exit end 1022 may cause the light incident to the optical coupler 102 to exit in a lateral direction.
As shown in fig. 1, the optical coupler 102 may be a grating coupler, i.e., the light-incident end 1021 may be a grating structure that is distributed in the lateral direction, whereby the grating structure may receive light entering the optical coupler in the longitudinal direction. In addition, the present embodiment is not limited to this, and the optical coupler 102 may be an end-face coupler, that is, the light incident end 1021 may be an end-face coupled structure.
In this embodiment, the light incident end 1031 of the fabry-perot resonator 103 may be laterally opposite to the light exit end 1021 of the optical coupler 102, so that light emitted in the lateral direction from the light exit end 1021 of the optical coupler 102 can be incident on the fabry-perot resonator 103. The fabry-perot resonator 103 is fabricated from the top silicon 101. The fabry-perot resonator 103 may have the shape of a waveguide with a length L.
As shown in fig. 1, the photodetector 104 is formed on the top silicon 101, and light emitted from the light emitting end 1032 of the fabry-perot resonator 103 can enter the top silicon 101 opposite to the light emitting end 1032. The top silicon 101 may guide incident light into the photodetector 104, and thus the photodetector 104 may detect light entering the top silicon 101 and output a current signal corresponding to the amount of incident light.
In this embodiment, the photodetector 104 may be a germanium (Ge) detector or a germanium tin (GeSn) detector. In addition, the present embodiment may not be limited thereto, and the photodetector 104 may be another kind of photodetector.
In the present embodiment, the heater 105 may be formed at a predetermined distance from the fabry-perot resonator 103, for example, the heater 105 may be formed above the fabry-perot resonator 103, or laterally. Within the predetermined distance, when the heater 105 is powered on to generate heat, the temperature of the fabry-perot resonator 103 can be changed according to the temperature of the heater 105.
In the present embodiment, the heater 105 may be made of, for example, polysilicon or amorphous silicon, and when current is applied, the heater 105 generates heat.
In the present embodiment, as shown in fig. 1, the on-chip waveguide loss measurement apparatus 100 further includes: a cover layer 107. The cover layer 107 may cover the optical coupler 102, the fabry-perot resonator 103, the photodetector 104, and the heater 105, whereby the cover layer 107 can protect the covered structure. The material of the cap layer 107 may be an insulating material, such as silicon dioxide.
As shown in fig. 1, the cover layer 107 may have an opening 1071, and the optical coupler 102 may be located below the opening 1071. For example, the light incident end 1021 of the optical coupler 102, which is a grating structure, may be located below the opening 1071, whereby light may be incident to the light incident end 1021 through the opening 1071.
Fig. 2 is a schematic diagram of a method of calculating waveguide loss using the on-chip waveguide loss measurement apparatus 100 of fig. 1, as shown in fig. 2, the method including:
In the present embodiment, in step 201, light may be irradiated from the opening 1071 to the light incident end 1021 of the optical coupler 102 through an optical fiber.
In step 202, the bias voltage of the heater 105 is changed, which causes the temperature of the fabry-perot resonator 103 to change, and the current value of the photocurrent output by the photodetector 104 changes periodically.
Fig. 3 is a diagram showing a variation of a current value of the photocurrent output from the photodetector 104 with a bias voltage of the heater 105. In fig. 3, the horizontal axis represents the bias voltage of the heater 105, the vertical axis represents the current value of the photocurrent output from the photodetector 104, and the unit of the horizontal axis and the unit of the vertical axis may be a custom unit (a.u.).
As shown in fig. 3, as the bias voltage of the heater 105 increases, the temperature of the fabry-perot resonator 103 gradually increases, and the current value of the photocurrent output by the photodetector 104 periodically changes, wherein the maximum value of the current value is Pmax, and the minimum value of the current value is Pmin.
In step 203, the loss α of the optical waveguide may be calculated according to the following equation (1):
in the above formula (1), L is the length of the fabry-perot cavity 103; pmax and Pmin are respectively the maximum value and the minimum value of the current value of the photocurrent output by the photodetector 104, and Pmax and Pmin can be obtained from the current signal output by the photodetector 104; r is an end face reflection coefficient of the fabry-perot cavity 103, and R is represented by the following formula (2):
η therein0Is SiO2Refractive index, ηeffIs the effective refractive index of the fabry-perot cavity 103 portion waveguide.
In the present embodiment, the fabry-perot resonator 103 has a waveguide structure in structure, and thus, the loss α of the waveguide of the fabry-perot resonator 103 can be calculated by the above equation (1).
According to this embodiment, a fabry-perot cavity is integrated in the on-chip waveguide loss measurement apparatus, after light enters the fabry-perot cavity 103 through the optical coupler 102, the photodetector 104 at the other end of the fabry-perot cavity detects an optical signal output from the fabry-perot cavity 104, the heater 105 adjusts the temperature of the fabry-perot cavity, and the loss of the optical waveguide in the top silicon 101 of the silicon-on-insulator (SOI) substrate 100 can be calculated by measuring the output optical signal of the fabry-perot cavity at different temperatures.
Example 2
Embodiment 2 provides a method for manufacturing an on-chip waveguide loss measurement device, which is used for manufacturing the on-chip waveguide loss measurement device described in embodiment 1.
Fig. 4 is a schematic diagram of a manufacturing method of the on-chip waveguide loss measuring apparatus of the present embodiment. As shown in fig. 4, in the present embodiment, the manufacturing method may include:
step 404 forms a heater 105 at a predetermined distance from the fabry-perot resonator 103.
As shown in fig. 4, the manufacturing method further includes:
In the present embodiment, the heater 105 may be formed on the lateral side or above the photodetector 104, wherein in the case where the heater 105 is formed above the photodetector 104, the steps 404 and 405 may be implemented by the following steps:
step 501, after step 403, forming a first cover layer covering the optical coupler 102, the fabry-perot resonator 103, and the photodetector 104;
step 502, forming a heater 105 on the surface of the first covering layer; and
step 503, forming a second cover layer covering the heater 105 and the remaining first cover layer exposed from the periphery of the heater 105.
In this embodiment, as shown in fig. 4, the manufacturing method further includes:
step 406 forms an opening 1071 in the cap layer 107, with the optocoupler 102 located below the opening 1071.
According to this embodiment, a fabry-perot cavity is integrated in the on-chip waveguide loss measurement apparatus, after light enters the fabry-perot cavity 103 through the optical coupler 102, the photodetector 104 at the other end of the fabry-perot cavity detects an optical signal output from the fabry-perot cavity 104, the heater 105 adjusts the temperature of the fabry-perot cavity, and the loss of the optical waveguide in the top silicon 101 of the silicon-on-insulator (SOI) substrate 100 can be calculated by measuring the output optical signal of the fabry-perot cavity at different temperatures.
The present application has been described in conjunction with specific embodiments, but it should be understood by those skilled in the art that these descriptions are intended to be illustrative, and not limiting. Various modifications and adaptations of the present application may occur to those skilled in the art based on the spirit and principles of the application and are within the scope of the application.
Claims (5)
1. An on-chip waveguide loss measurement apparatus comprising:
an optical coupler formed in top silicon of a silicon-on-insulator (SOI) substrate;
a Fabry-Perot resonant cavity formed in the top silicon, a light incident end of the Fabry-Perot resonant cavity being laterally opposite to a light exit end of the optical coupler;
a photodetector formed on the top layer silicon; and
a heater formed at a predetermined distance of the Fabry-Perot resonant cavity.
2. The on-chip waveguide loss measurement device of claim 1, further comprising:
a cover layer covering the optical coupler, the Fabry-Perot resonant cavity, the photodetector, and the heater.
3. The on-chip waveguide loss measurement apparatus of claim 2,
the cover layer has an opening, and the optical coupler is located below the opening.
4. The on-chip waveguide loss measurement apparatus of claim 3,
the optical coupler is an end face coupler or a grating coupler.
5. The on-chip waveguide loss measurement apparatus of claim 3,
the photodetector is a germanium (Ge) detector or a germanium tin (GeSn) detector.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117191358A (en) * | 2023-09-21 | 2023-12-08 | 苏州猎奇智能设备有限公司 | Silicon optical chip testing device and testing method thereof |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117191358A (en) * | 2023-09-21 | 2023-12-08 | 苏州猎奇智能设备有限公司 | Silicon optical chip testing device and testing method thereof |
| CN117191358B (en) * | 2023-09-21 | 2024-02-13 | 苏州猎奇智能设备有限公司 | Silicon optical chip testing device and testing method thereof |
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