CN108873182B - Optical switch chip - Google Patents
Optical switch chip Download PDFInfo
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- CN108873182B CN108873182B CN201710335111.1A CN201710335111A CN108873182B CN 108873182 B CN108873182 B CN 108873182B CN 201710335111 A CN201710335111 A CN 201710335111A CN 108873182 B CN108873182 B CN 108873182B
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/35—Optical coupling means having switching means
- G02B6/354—Switching arrangements, i.e. number of input/output ports and interconnection types
Abstract
The application provides an optical switch chip, this optical switch chip includes: the device comprises a first device layer, a second device layer and a first bottom layer. The first device layer is connected with the first bottom layer; the first device layer and the second device layer are distributed with an optical switch matrix, N optical coupling devices and a plurality of electrodes; the first device layer and the second device layer are bonded together through vertical welding of a plurality of electrodes of the first device layer and a plurality of electrodes of the second device layer; the N photo-coupling devices of the first device layer are located at the same position on the first device layer as the N photo-coupling devices of the second device layer are located on the second device layer. This optical switch chip is through being in the same place two device layer bonds that the structure is the same for optic fibre can follow the same position coupling of optical switch chip, and light after the coupling can directly get into the optical switch matrix on two device layers, thereby has avoided longer waveguide to walk line and cross waveguide, can not increase the insertion loss of optical switch chip.
Description
Technical Field
The present application relates to communications technologies, and in particular, to an optical switch chip.
Background
With the development of communication networks, higher requirements are put on the transmission rate and the communication quality of the communication networks. Compared with the traditional communication network, the all-optical switching has the advantages of low energy consumption and large capacity, so that the all-optical switching becomes the development direction of future broadband communication. The optical switch matrix is a key device for realizing important functions such as routing, wavelength selection, optical cross connection and the like in future optical network all-optical switching. An optical switch chip with an optical switch matrix built in is arranged on node equipment of a communication network to realize the function of all-optical switching.
In the prior art, an optical switch chip is coupled to an optical fiber through an edge coupler, a Polarization rotating beam Splitter (PSR) is used to separate a TE mode and a TM mode of the optical fiber and convert the two modes into the TE mode, and after the two modes pass through different single-Polarization optical switch matrices, a Polarization rotating beam Combiner (PRC) is used to combine the two modes, and the two modes are coupled to the optical fiber through the edge coupler.
However, in the optical switch chip in the prior art, the waveguide routing between the edge coupler and the single polarization matrix switch is long, and there is a cross waveguide between the edge coupler and the single polarization matrix switch, which results in an excessively large insertion loss (loss of optical power from the input port to the output port) of the optical switch chip.
Disclosure of Invention
The application provides an optical switch chip for solve the problem that the waveguide between the edge coupler of the optical switch chip and the single polarization matrix switch in the prior art is too long to walk and the optical switch chip insertion loss caused by the existence of crossed waveguides is too large.
The optical switch chip provided by the application comprises: the device comprises a first device layer, a second device layer and a first bottom layer.
Wherein the first device layer is connected with the first bottom layer;
an optical switch matrix, N optical coupling devices and a plurality of electrodes are distributed on the first device layer and the second device layer, wherein N is an integer greater than 1;
the first device layer and the second device layer are bonded together through vertical welding of the electrode of the first device layer and the corresponding electrode of the second device layer;
the N photo-coupling devices of the first device layer are located at the same position on the first device layer as the N photo-coupling devices of the second device layer are located on the second device layer.
This optical switch chip is through being in the same place two device layer bonds that the structure is the same for optic fibre can follow the same position coupling of optical switch chip, and the light after the coupling can directly get into the optical switch matrix on two device layers, thereby has avoided longer waveguide to walk line and cross waveguide, and then can not increase the insertion loss of optical switch chip.
In one possible design, the electrodes of the first device layer are connected to the electrodes of the second device layer in a one-to-one correspondence.
The electrodes of the first device layer 1 and the electrodes of the second device layer 2 are connected in a one-to-one correspondence mode, so that the first device layer and the second device layer can be driven simultaneously through one circuit, and the structural complexity of the optical switch chip is reduced.
In one possible design, the electrodes of the first device layer are connected to the electrodes of the second device layer in a one-to-one correspondence.
In one possible design, the optical switch matrix of the first device layer and the optical switch matrix of the second device layer are both single polarization optical switch matrices.
The optical switch matrixes on the first device layer and the second device layer are set to be single-polarization optical switch matrixes, so that the effect of double-polarization switch matrixes is realized by using the two single-polarization optical switch matrixes, and the structural complexity of the optical switch chip is reduced on the basis of ensuring the functions of the optical switch chip.
In one possible design, the optical coupling device of the first device layer and the optical coupling device of the second device layer are both edge couplers.
In one possible design, the edge coupler of the first device layer and the edge coupler of the second device layer respectively couple two single-polarization optical signals separated by the birefringent crystal;
the birefringent crystal is located outside the optical switch chip and is used for separating two mutually orthogonal optical signals transmitted by the optical fiber into two single-polarization optical signals.
In one possible design, the edge coupler of the first device layer is configured to couple a first single-polarization optical signal transmitted by a polarization-maintaining optical fiber connected to the edge coupler of the first device layer;
the edge coupler of the second device layer is used for coupling a second single-polarization optical signal transmitted by the polarization-maintaining optical fiber connected with the edge coupler of the second device layer.
In one possible design, the optical coupling device of the first device layer and the optical coupling device of the second device layer are both grating couplers;
the grating coupler of the first device layer and the grating coupler of the second device layer are respectively coupled with two single-polarization optical signals.
In one possible design, the optical switch chip further includes: a second bottom layer;
the second bottom layer is connected with the second device layer;
the electrode of the first device layer is connected with a driving circuit through a through hole arranged on the first device layer.
In one possible design, the electrodes of the second device layer are bonded to the driver circuit by vertical soldering.
In one possible design, the electrodes of the second device layer are connected to the driving circuit through metal leads.
Drawings
Fig. 1 is a schematic diagram of a network structure provided in an embodiment of the present application;
FIG. 2(a) is a cross-sectional view of the core layer of a slab waveguide;
FIG. 2(b) is a perspective side view of a slab waveguide;
FIGS. 3(a) and 3(b) are two exemplary crossed waveguides;
fig. 4 is a schematic structural diagram of an optical switch chip provided in the prior art;
fig. 5 is a block diagram of a first embodiment of an optical switch chip provided in the present application;
fig. 6 is a schematic combination diagram of a first embodiment of an optical switch chip provided in the present application;
fig. 7 is a schematic diagram illustrating internal signal processing of an optical switch chip according to the present application;
FIG. 8 is a schematic diagram of a birefringent crystal polarization splitter of the optical switch chip provided herein;
fig. 9 is a schematic diagram of a polarization maintaining optical fiber of an optical switch chip according to the present application transmitting a single-polarization optical signal;
FIG. 10 is a schematic diagram of grating coupling of an optical switch chip provided herein;
FIG. 11 is a schematic diagram of electrical packaging of an optical switch chip including a second bottom layer using a TSV approach;
FIG. 12 is a schematic diagram of an optical switch Chip electrically packaged using Flip Chip;
FIG. 13 is a schematic diagram of electrical packaging of an optical switch chip using a Wire Bonding approach;
FIG. 14 is a schematic diagram of an optical switch chip structure when the birefringent crystal optical coupling and TSV electrical packaging are combined;
FIG. 15 is a schematic diagram of an optical switch Chip structure when the birefringent crystal optical coupling mode is combined with the Flip Chip electrical packaging mode;
FIG. 16 is a schematic diagram of an optical switch chip structure when a birefringent crystal optical coupling mode is combined with a Wire Bonding electrical packaging mode;
fig. 17 is a schematic structural diagram of an optical switch chip when a polarization maintaining fiber optical coupling mode and a TSV package mode are combined;
FIG. 18 is a schematic diagram of an optical switch Chip structure when a polarization maintaining fiber optical coupling mode is combined with a Flip Chip packaging mode;
FIG. 19 is a schematic diagram of an optical switch chip structure when a polarization maintaining fiber optical coupling mode is combined with a Wire Bonding packaging mode;
fig. 20 is a schematic structural diagram of an optical switch chip when the grating coupling manner is combined with the TSV packaging manner;
FIG. 21 is a schematic diagram of an optical switch Chip structure when a grating coupling manner is combined with a Flip Chip packaging manner;
fig. 22 is a schematic structural diagram of an optical switch chip when a grating coupling manner and a Wire Bonding packaging manner are combined.
Detailed Description
The optical switch chip provided by the present application may be applied to a network system shown in fig. 1 (fig. 1 is a schematic diagram of a network structure provided by the embodiment of the present application). As shown in fig. 1, the network system includes a backbone network, a metropolitan area network, a data center, and the like, where each of the networks includes a plurality of nodes, and the optical switch chip provided in the present application may be applied to the nodes for performing optical signal switching. The optical switch chip provided by the present application can be applied to the nodes 1, 2, 3, 4, 5, 6, 7 and 8 in fig. 1. For example, for the node 4, the optical switch chip provided by the present application is applied to the node, so that optical signal exchange between the backbone network and the metropolitan area network can be realized. For the node 8, the optical switch chip provided by the present application is applied to the node, so that optical signal exchange between the data center and the metropolitan area network can be realized. In addition, in each kind of network internal node, the optical switch chip provided by the application can also be applied to perform optical signal switching in the network.
In order to better explain the technical solution of the present application, some terms related to the present application are explained below to facilitate understanding by those skilled in the art.
(1) Waveguide
Waveguides are the most fundamental structure in silicon-based chips for connecting and forming various devices. The waveguide is composed of a core layer composed of a high-refractive-index material, a substrate composed of a low-refractive-index material and a base. Among them, the strip waveguide is a typical waveguide structure.
Fig. 2(a) is a cross-sectional view of a core layer of a strip waveguide, and fig. 2(b) is a perspective side view of the strip waveguide.
(2) Cross waveguide
The chip is provided with a plurality of devices, waveguides connected among the devices may be crossed, when two waveguides are crossed, a crossed waveguide is required to be connected at the crossed position of the two waveguides, and the crossed waveguide is a specific functional device. Fig. 3(a) and 3(b) are two typical crossed waveguides. When the crossed waveguide exists in the chip, the insertion loss of the chip can be increased, and the insertion loss caused by the crossed waveguide can be minimized by optimally designing the structure of the crossed part, for example, the structure shown in fig. 3(a) is that two waveguides are directly crossed, the caused insertion loss is the largest, and the structure shown in fig. 3(b) can reduce the insertion loss by increasing the broadband at the crossed part compared with fig. 3 (a).
However, optimizing the structure of the cross portion can only reduce the insertion loss caused by the cross waveguide, but cannot completely eliminate the insertion loss, so that the insertion loss of the chip is increased as long as the cross waveguide exists in the chip.
(3) Polarization state of optical fiber
Optical fibers are short hand for optical fibers, and are fibers made of glass or plastic, circular in cross-section, that can be used as a light conducting tool. When an optical signal propagates through an optical fiber, the light vector may have a plurality of vibration states in a plane perpendicular to the propagation direction, and the specific vibration mode in the plane is called the polarization state of the light. In the ideal case where the optical fiber is strictly cylindrical and the material is isotropic, the optical signal propagating in the optical fiber can be decomposed into two orthogonal polarization states, which can be referred to as the X-polarization state and the Y-polarization state, respectively. The modes of the two orthogonal polarization states are degenerate, i.e., the mode of the X-direction polarization state does not couple with the mode of the orthogonal Y-direction polarization state.
(4) Polarization maintaining optical fiber
In the ideal situation where the optical fiber is strictly cylindrical and the material is isotropic, the optical signal propagating in the optical fiber can be decomposed into two orthogonal polarization states, and in the actual situation, the optical fiber is not strictly cylindrical or the material has small fluctuations of anisotropy, which will break the degeneracy of the polarization mode, thereby causing the coupling between the two polarization states. Therefore, in actual transmission, even if the optical signal is input into the optical fiber in only the X polarization state, the optical signal in the optical fiber will be changed into a mixed state of the X polarization state and the Y polarization state after being transmitted through a section of optical fiber. Similarly, the signal in the Y polarization state is transmitted and then becomes a mixed state of the X polarization state and the Y polarization state. This is clearly unacceptable for devices that do not allow the change in the polarization state of light, and polarization-maintaining fibers have therefore been proposed to address the problem of the change in the polarization state of light during transmission.
The polarization maintaining fiber is a special fiber which can maintain the polarization state of an incident beam polarized in a certain direction by artificially increasing the birefringence of the fiber in design.
As long as the polarization direction of light incident into the optical fiber is parallel to one axis of the polarization maintaining optical fiber, the polarization state of the light does not change during transmission even if the optical fiber is bent.
If the polarization axis of the incident light forms an included angle with the fast and slow axes of the optical fiber, the polarization state of the incident light is continuously and periodically changed by taking beat length as a period in the transmission process.
(5) Polarization state and TE mode, TM mode
As previously described, an optical signal propagating within an optical fiber may be decomposed into two orthogonal polarization states, which may be referred to as an X-polarization state and a Y-polarization state, respectively. When an optical signal is coupled from an optical fiber to a chip waveguide, the optical signal mode in the waveguide is divided into a Transverse Electric Wave (TE) mode and a Transverse Magnetic Wave (TM) mode. Here, the TE mode means that an electric field component in the electromagnetic wave propagation direction is zero, and the TM mode means that a magnetic field component in the electromagnetic wave propagation direction is zero.
The TE mode is arranged from high to low according to the effective refractive index, and may be divided into a TE zero-order mode (TE0), a TE first-order mode (TE1), a TE second-order mode (TE2), and the TM mode is arranged from high to low according to the effective refractive index, and may be divided into a TM zero-order mode (TM0), a TM first-order mode (TM1), a TM (TM2) second-order mode, and the like. In the following embodiments of the present application, the TE mode refers to TE0, and the TM mode refers to TM0, which will not be described in detail below.
(6) Single-polarization optical switch matrix and double-polarization optical switch matrix
Light coupled into the TE or TM modes in the optical switch chip is routed, wavelength selected, optically cross-connected, etc. through the optical switch matrix. Optical switch matrices can be divided into single polarization optical switch matrices and dual polarization optical switch matrices. A single polarization switch matrix handles primarily one mode of light, while the other mode of light is poorly handled. The dual polarization switch matrix can handle both modes of light.
It is to be understood that the appearances of "a plurality" in the embodiments of the present application mean two or more.
Fig. 4 is a schematic structural diagram of an optical switch chip provided IN the prior art, and as shown IN fig. 4, the optical switch chip is coupled to an optical fiber through edge couplers (IN _ EC1 to IN _ EC8 IN fig. 4), inside the optical switch chip, a PSR is used to separate polarization states corresponding to a TE mode and a TM mode of the optical fiber, and convert the polarization states into the TE mode, light of the two modes respectively passes through different single-polarization optical switch matrices, and then the two modes are combined by a PRC, and then coupled to the optical fiber through the edge couplers (OUT _ EC1 to OUT _ EC8 IN fig. 4).
As can be seen from fig. 4, when two optical signals separated from one PSR are respectively connected to two single-polarization optical switch matrices, a crossed waveguide (where a solid line crosses a dotted line in fig. 4) is generated between the PSR and the optical switch matrices, and the waveguide routing is long, thereby causing an excessive insertion loss of the optical switch chip.
The optical switch chip according to the embodiments of the present application is directed to solving the above-mentioned problems of the prior art.
The following describes the technical solutions of the present application and how to solve the above technical problems with specific examples. The following several specific embodiments may be combined with each other, and details of the same or similar concepts or processes may not be repeated in some embodiments.
Fig. 5 is a block structure diagram of a first embodiment of an optical switch chip provided in the present application, and fig. 6 is a combination schematic diagram of the first embodiment of the optical switch chip provided in the present application, as shown in fig. 5 and fig. 6, the optical switch chip includes a first device layer 1, a second device layer 2, and a first bottom layer 3.
Wherein the first device layer 1 is connected to the first bottom layer 3.
Specifically, the first device layer 1 is bonded to the first underlying layer 3.
An optical switch matrix, N optical coupling devices and a plurality of electrodes are distributed on the first device layer 1 and the second device layer 2, wherein N is an integer larger than 1.
The first device layer 1 and the second device layer 2 are bonded together by vertical welding of electrodes of the first device layer 1 and corresponding electrodes of the second device layer 2.
Alternatively, each electrode on the first device layer 1 may be vertically soldered to its corresponding electrode on the second device layer 2; or, selecting a part of electrodes on the first device layer 1, wherein each electrode in the part of electrodes is vertically welded with a corresponding electrode of the electrode on the second device layer 2; alternatively, a portion of the electrodes on the second device layer 2 is selected, each of which is perpendicularly soldered to its corresponding electrode on the first device layer 1.
The N photo-coupling devices of the first device layer 1 are located at the same position on the first device layer 1 as the N photo-coupling devices of the second device layer 2 are located on the second device layer 2.
The positions of the N optical coupling devices of the first device layer 1 on the first device layer 1 are the same as the positions of the N optical coupling devices of the second device layer 2 on the second device layer 2, specifically, after the first device layer 1 and the second device layer 2 are bonded together, the positions of the N optical coupling devices of the first device layer 1 are the same as the positions of the N optical coupling devices of the second device layer 2. More specifically, the phrase "same position" in this embodiment means that the optical coupling device on the upper device layer can just block the optical coupling device on the lower device layer when the first device layer 1 and the second device layer 2 after bonding are viewed from above.
Specifically, the first underlayer 3 includes a base and a substrate.
Specifically, the first device layer 1 and the second device layer 2 have the same structure, that is, the first device layer 1 and the second device layer 2 have the same number of optical couplers for optical coupling, the same number of electrodes for electrical connection, and the same function and structure of the optical switch matrix.
The first device layer 1 and the second device layer 2 are bonded together by vertically welding a plurality of electrodes of the first device layer 1 and a plurality of electrodes of the second device layer 2, so that the first device layer and the second device layer satisfy axial symmetry, and further, since the N photo-couplers of the first device layer 1 are located at the same positions on the first device layer 1 as the N photo-couplers of the second device layer 2, therefore, the optical coupling regions of the first device layer and the second device layer can be in the same region after bonding, the input optical signal can be coupled into the input side optical coupling device of the first device layer 1 and the input side optical coupling device of the second device layer 2 from the same position of the optical switch chip, the coupled light directly enters the optical switch matrix of the first device layer 1 and the optical switch matrix of the second device layer 2, so that crossed waveguides and longer waveguide routing are avoided. Further, the optical signal entering the optical switch matrix of the first device layer 1 is processed and then enters the output-side optical coupler directly connected to the optical switch matrix, and the optical signal entering the optical switch matrix of the second device layer 2 is processed and then enters the output-side optical coupler directly connected to the optical switch matrix. And the output optical coupler couples the output optical signal to the optical fiber at the output end. That is, the optical switch matrix of the first device layer 1 and the optical switch matrix of the second device layer 2 are directly connected to the output optical coupler, so that the crossed waveguides and the longer waveguide routing are also avoided on the output side.
Alternatively, the electrodes of the first device layer 1 and the second device layer 2 may be vertically soldered by using a Flip-chip bonding (Flip-chip bonding) method, specifically, the upper and lower electrodes of the two device layers are aligned, the electrode metal is exposed on the surface, an Under-Bump-Metallization (UBM) process is performed on the metal surface, and then the solder is filled between the electrodes to solder the upper and lower electrodes.
In this embodiment, two device layers with the same structure are bonded together, so that the optical fiber can be coupled from the same position of the optical switch chip, and the coupled light can directly enter the optical switch matrix of the two device layers, thereby avoiding longer waveguide routing and crossed waveguide, and further not increasing the insertion loss of the optical switch chip.
In another embodiment, optionally, the optical switch matrix on the first device layer 1 and the optical switch matrix on the second device layer 2 are both single polarization optical switch matrices.
Specifically, before light in different polarization states in the optical fiber is coupled with the optical coupling devices of the first device layer 1 and the second device layer 2, light in different polarization states may be separated in a specific manner (for example, using a polarization beam splitter), and the separated light may be coupled with the optical coupling device of the first device layer 1 and the optical coupling device of the second device layer 2 in a TE mode or a TM mode, that is, light entering the optical switch matrix of the first device layer 1 and light entering the second device layer 2 may be light in the same mode, and therefore, the optical switch matrix of the first device layer 1 and the optical switch matrix of the second device layer 2 may be single-polarization optical switch matrices having the same structure to process light in one mode.
In this embodiment, the optical switch matrices on the first device layer 1 and the second device layer 2 are both single-polarization optical switch matrices, so that the effect of a dual-polarization switch matrix is achieved by using two single-polarization optical switch matrices, and the structural complexity of the optical switch chip is reduced on the basis of ensuring the functions of the optical switch chip.
In another embodiment, the electrodes of the first device layer 1 and the electrodes of the second device layer 2 are connected in a one-to-one correspondence.
Specifically, assuming that 3 electrodes of a1, a2 and A3 are arranged on the first device layer 1, three electrodes of B1, B2 and B3 are arranged on the second device layer 2, when the first device layer and the second device layer are vertically welded, the positions of a1 and B1 are the same, the positions of a2 and B2 are the same, and the positions of A3 and B3 are the same, the a1 and B1 can be welded together, the a2 and B2 can be welded together, and the A3 and B3 can be welded together, so that the electrodes of the first device layer 1 and the electrodes of the second device layer 2 are connected in a one-to-one correspondence.
In this embodiment, the electrodes of the first device layer 1 and the electrodes of the second device layer 2 are connected in a one-to-one correspondence manner, so that the first device layer and the second device layer can be driven simultaneously by one circuit, and the structural complexity of the optical switch chip is reduced. The specific implementation will be described in detail in the following examples.
Based on the optical switch chip described in the above embodiments, fig. 7 is a schematic diagram of internal signal processing of the optical switch chip according to the present application, as shown in fig. 7, an input optical signal is coupled from the same portion of the optical switch chip to the input-side optical coupling device of the first device layer 1 and the input-side optical coupling device of the second device layer 2 (fig. 7 is described from a top view, the first device layer is covered by the second device layer, but the processing process of the internal optical signal is the same as that of the second device layer), and then enters the optical switch matrix of the first device layer 1 and the optical switch matrix of the second device layer 2, respectively, and the optical signal processed by the optical switch matrix of the first device layer 1 is output to the output-side optical coupling device, the optical signal processed by the optical switch matrix of the second device layer 2 is output to the output side optical coupling device, the optical signals of the output side optical coupling device of the first device layer 1 and the output side optical coupling device of the second device layer 2 are recombined and output.
The following describes an optical coupling method and an electrical packaging method of the optical switch chip according to the present application.
The optical switch chip according to the present application may specifically use the following three optical coupling methods:
(1) optical coupling through birefringent crystals
In this mode, the edge coupler of the first device layer 1 and the edge coupler of the second device layer 2 respectively couple two single-polarization optical signals separated by the birefringent crystal, the birefringent crystal is located outside the optical switch chip, and the birefringent crystal is used for separating two mutually orthogonal optical signals transmitted by the optical fiber into two single-polarization optical signals.
Specifically, in this method, a birefringent crystal is used at the input side of the optical switch chip, and light in different polarization states in the optical fiber is spatially separated by using the birefringent effect of the birefringent crystal, and two separated single-polarization optical signals are respectively coupled with the edge coupler on the first chip layer 1 and the edge coupler on the second chip layer 2, and then respectively enter the optical switch matrix of the first chip layer 1 and the optical switch matrix of the second chip layer 2 for processing. At the output side of the optical switch chip, two single-polarization optical signals processed by the optical switch matrix are respectively connected with the edge coupler on the first chip layer 1 and the edge coupler on the second chip layer 2, and the two single-polarization optical signals are coupled into the optical fiber through the birefringent crystal of the output part. Therefore, the optical signals of two orthogonal polarization states in the input optical fiber are respectively processed by the two optical switch matrixes and then merged into the output optical fiber for output.
Specifically, taking the birefringent crystal at the input side as an example, the thickness, structure, material, and angle between the birefringent crystal and the optical fiber may be adjusted according to the actual distance between the first device layer 1 and the second device layer 2 in the optical switch chip, so that two single-polarization optical signals separated by the birefringent crystal may be coupled with the edge coupler of the first device layer 1 and the edge coupler of the second device layer 2, respectively, and thus longer waveguide routing and cross waveguide are avoided. The arrangement of the birefringent crystal at the output side is similar to that at the input side, and is not described in detail.
It should be noted that specific parameter values of the thickness, structure, material and angle of the birefringent crystal with respect to the optical fiber may be obtained through experiments and the like based on the distance between the first chip layer 1 and the second chip layer 2, which is not specifically limited in this application.
Fig. 8 is a schematic partial view of a birefringent crystal of the optical switch chip provided by the present application, as shown in fig. 8, light entering the birefringent crystal from an optical fiber passes through the birefringent crystal, and becomes two single-polarized light signals spatially separated from each other, and the two single-polarized light signals are coupled with an edge coupler on the first chip layer 1 and an edge coupler on the second chip layer 2, respectively.
Alternatively, as described above, the optical switch matrix of the first device layer 1 and the optical switch matrix of the second device layer 2 may be single polarization switch matrices with the same structure, for example, both the two optical switch matrices process light in the TE mode, and therefore, in this embodiment, two single polarization optical signals separated by the birefringent crystal may be coupled to light in the TE mode with both the edge coupler of the first device layer 1 and the edge coupler of the second device layer 2, and then processed by the single polarization optical switch matrices with the same structure.
(2) Optical coupling via polarization maintaining fiber
In this manner, optionally, the light transmitted in the optical fiber may be divided and polarized by using an optical fiber polarization dividing device (e.g., an optical fiber splitter) outside the optical switch chip, and after the division and polarization division, the light may be coupled with the edge coupler of the first device layer 1 and the edge coupler of the second device layer 2 through polarization maintaining optical fibers, respectively.
Specifically, two single-polarization optical signals are output after the optical fiber polarization splitter splits the polarization and are transmitted through the polarization maintaining optical fibers, one polarization maintaining optical fiber is connected with the side coupler of the first device layer 1, and the other polarization maintaining optical fiber is connected with the side coupler of the second device layer 2. Accordingly, the edge coupler of the first device layer 1 is configured to couple a first single-polarized optical signal transmitted by the polarization maintaining fiber connected to the edge coupler of the first device layer 1, and the edge coupler of the second device layer 2 is configured to couple a second single-polarized optical signal transmitted by the polarization maintaining fiber connected to the edge coupler of the second device layer 2.
Fig. 9 is a schematic diagram of a polarization maintaining optical fiber of an optical switch chip provided in the present application for transmitting a single-polarization optical signal, and as shown in fig. 9, two single-polarization optical signals output from an optical fiber polarization splitter (not shown) are respectively transmitted through a polarization maintaining optical fiber 1 and a polarization maintaining optical fiber 2, where the polarization maintaining optical fiber 1 outputs a first single-polarization optical signal and the polarization maintaining optical fiber 2 outputs a second single-polarization optical signal.
(3) Optical coupling by grating coupler
In this manner, the optical coupling device of the first device layer and the optical coupling device of the second device layer are both grating couplers. The grating coupler of the first device layer and the grating coupler of the second device layer are respectively coupled with two single-polarization optical signals.
Specifically, the grating coupler of the first device layer and the grating coupler of the second device layer may be specifically designed, and a corresponding grating period and an etching depth are selected according to a distance between the first device layer and the second device layer, so that light in different polarization states in the optical fiber is respectively coupled into the first device layer and the second device layer. The grating coupler is connected with the optical switch matrix, and the coupled single-polarization optical signal is transmitted to the optical switch matrix for processing.
It should be noted that, in the implementation process of this embodiment, the substrate corresponding to the grating region on the device layer closer to the optical fiber needs to be removed, and the substrate may be selectively removed or retained according to the actual grating design, and in addition, the substrate and the substrate in other regions on the device layer closer to the optical fiber may be selectively removed or retained.
Fig. 10 is a schematic diagram illustrating grating coupling of an optical switch chip provided in the present application, and as shown in fig. 10, an optical signal transmitted from an optical fiber is coupled with a grating on the first device layer 1 and a grating on the second device layer 2, respectively.
The electrical packaging of the optical switch chip of the present application is described below.
The optical switch chip related to the present application can specifically use the following three electrical packaging modes:
(1) electrical packaging using Through Silicon Via (TSV) approach
In accordance with this embodiment, the optical switch chip according to the present invention further includes a second base layer 4, and fig. 11 is a schematic view of electrically packaging the optical switch chip including the second base layer by using the TSV method, where as shown in fig. 11, the second base layer 4 is connected to the second device layer 2, and the electrode of the first device layer 1 is connected to the driving circuit through a through hole provided in the first base layer. The driving circuit may be a driving circuit located outside the optical switch chip and supplying power to the optical switch chip. In a specific implementation, a through hole may be formed from one side of the optical switch chip (the side corresponding to the first device layer 1 in fig. 11), and all electrodes may be connected to the TSV interposer and then connected to the driving circuit. Each electrode simultaneously connects corresponding devices on the first device layer 1 and the second device layer 2, and simultaneously drives the first device layer 1 and the second device layer 2.
(2) Electrical packaging using Flip Chip approach
Fig. 12 is a schematic diagram of electrical packaging of the optical switch Chip using Flip Chip method, as shown in fig. 12, an interposer is disposed on the second device layer 2 (i.e. the device layer without the bottom layer connected thereto), and the electrodes of the second device layer 2 are connected to the interposer using Flip Chip method, and then connected to the driving circuit. So that the second device layer 2 is bonded to the driving circuit by vertical soldering.
Alternatively, the driving Circuit may be a Printed Circuit Board (PCB) driving Board.
(3) Electrical packaging using Wire Bonding
Fig. 13 is a schematic diagram of electrical packaging of the optical switch chip by using Wire Bonding, and as shown in fig. 13, the electrodes of the second device layer 2 (i.e., the device layer without the bottom layer connected thereto) are connected to the driving circuit one by using metal wires. Alternatively, the electrodes of the second device layer 2 may be connected to the ceramic transition shell one by using metal leads, and then the ceramic transition shell is connected to the PCB driving board, so as to connect the second device layer to the driving circuit.
In the above description, three optical coupling manners and three electrical packaging manners of the optical switch chip related to the present application are introduced, and in a specific implementation process, the three optical coupling manners and the three electrical packaging manners may be arbitrarily combined to implement the optical switch chip related to the present application. The specific combination mode is as follows:
(1) the optical coupling mode is birefringent crystal optical coupling mode, and the electric packaging mode is TSV packaging mode
Fig. 14 is a schematic structural diagram of an optical switch chip when the optical coupling manner of the birefringent crystal is combined with the TSV electrical package manner, and as shown in fig. 14, the birefringent crystal located outside the optical switch chip receives an optical signal transmitted by an optical fiber and splits the optical signal into two single-polarization optical signals, and the two single-polarization optical signals are respectively coupled with optical coupling devices of an upper device layer and a lower device layer, so as to complete optical coupling of the optical switch chip. And in the optical switch chip, the electrodes on the first device layer are connected to the intermediate layer one by one in a TSV mode and then connected to the driving circuit, so that power supply to the optical switch chip is completed.
(2) The optical coupling mode is birefringent crystal optical coupling mode, and the electric packaging mode is Flip Chip packaging mode
Fig. 15 is a schematic structural diagram of an optical switch Chip when a birefringent crystal optical coupling mode and a Flip Chip electrical packaging mode are combined, and as shown in fig. 15, a birefringent crystal located outside the optical switch Chip receives an optical signal transmitted by an optical fiber and separates the optical signal into two single-polarization optical signals, and the two single-polarization optical signals are respectively coupled with optical coupling devices of an upper device layer and a lower device layer, so that optical coupling of the optical switch Chip is completed. And vertically welding the second device layer 2 with the intermediate layer and the PCB inside the optical switch chip, so that the second device layer 2 is bonded with the PCB together, thereby completing the power supply of the optical switch chip.
(3) The optical coupling mode is birefringent crystal optical coupling mode, and the electric packaging mode is Wire Bonding packaging mode
Fig. 16 is a schematic structural diagram of an optical switch chip when a birefringent crystal optical coupling mode and a Wire Bonding electrical packaging mode are combined, and as shown in fig. 16, a birefringent crystal located outside the optical switch chip receives an optical signal transmitted by an optical fiber and separates the optical signal into two single-polarized optical signals, and the two single-polarized optical signals are respectively coupled with edge couplers of an upper device layer and a lower device layer, so as to complete optical coupling of the optical switch chip. In the optical switch chip, the electrodes of the second device layer 2 are connected with a ceramic transfer shell (or other types of transfer devices) one by using metal leads, and the ceramic transfer shell is connected with a PCB (printed circuit board) driving board.
It should be noted that, for the sake of simplicity, fig. 15 only shows a portion of the electrodes connected to the ceramic transition housing, and in practice, all the electrodes need to be connected to the ceramic transition housing.
(4) The optical coupling mode is a polarization maintaining optical fiber optical coupling mode, and the electric packaging mode is a TSV packaging mode
Fig. 17 is a schematic structural diagram of an optical switch chip when the polarization maintaining fiber optical coupling mode is combined with the TSV package mode, and as shown in fig. 17, two polarization maintaining fibers are disposed outside the optical switch chip to transmit two single-polarization optical signals, respectively, and the single-polarization optical signals output from the polarization maintaining fibers are coupled with the edge couplers of the upper and lower device layers, respectively, so as to complete optical coupling of the optical switch chip. And in the optical switch chip, the electrodes on the first device layer are connected to the intermediate layer one by one in a TSV mode and then connected to the driving circuit, so that power supply to the optical switch chip is completed.
(5) The optical coupling mode is polarization maintaining optical fiber optical coupling mode, and the electrical packaging mode is Flip Chip packaging mode
Fig. 18 is a schematic structural diagram of an optical switch Chip when the polarization maintaining fiber optical coupling mode is combined with the Flip Chip packaging mode, and as shown in fig. 18, two polarization maintaining fibers are arranged outside the optical switch Chip to transmit two single-polarization optical signals respectively, and the single-polarization optical signals output from the polarization maintaining fibers are coupled with side couplers of an upper device layer and a lower device layer respectively, so as to complete optical coupling of the optical switch Chip. And vertically welding the second device layer 2 with the intermediate layer and the PCB inside the optical switch chip, so that the second device layer 2 is bonded with the PCB together, thereby completing the power supply of the optical switch chip.
(6) The optical coupling mode is a polarization maintaining optical fiber optical coupling mode, and the electric packaging mode is a Wire Bonding packaging mode
Fig. 19 is a schematic structural diagram of an optical switch chip when a polarization maintaining fiber optical coupling mode and a Wire Bonding packaging mode are combined, and as shown in fig. 19, two polarization maintaining fibers are arranged outside the optical switch chip to respectively transmit two single-polarization optical signals, and the single-polarization optical signals output from the polarization maintaining fibers are respectively coupled with edge couplers of an upper device layer and a lower device layer, so that optical coupling of the optical switch chip is completed. In the optical switch chip, the electrodes of the second device layer 2 are connected with a ceramic transfer shell (or other types of transfer devices) one by using metal leads, and the ceramic transfer shell is connected with a PCB (printed circuit board) driving board.
It should be noted that, for the sake of simplicity, only a portion of the electrodes are shown in fig. 18 to be connected to the ceramic transition housing, and in practice, all the electrodes need to be connected to the ceramic transition housing.
(7) The optical coupling mode is a grating coupling mode, and the electric packaging mode is a TSV packaging mode
Fig. 20 is a schematic structural diagram of an optical switch chip when the grating coupling method and the TSV packaging method are combined, and as shown in fig. 20, two polarization states of light output from an optical fiber are respectively coupled to a grating coupler of the first device layer 1 and a grating coupler of the second device layer 2, so that optical coupling to the optical switch chip is completed. And in the optical switch chip, the electrodes on the first device layer are connected to the intermediate layer one by one in a TSV mode and then connected to the driving circuit, so that power supply to the optical switch chip is completed.
(8) The optical coupling mode is a grating coupling mode, and the electric packaging mode is a Flip Chip packaging mode
Fig. 21 is a schematic structural diagram of an optical switch Chip when the grating coupling method and Flip Chip packaging method are combined, and as shown in fig. 21, light in two polarization states output from an optical fiber is respectively coupled to a grating coupler of the first device layer 1 and a grating coupler of the second device layer 2, so that optical coupling to the optical switch Chip is completed. And vertically welding the second device layer 2 with the intermediate layer and the PCB inside the optical switch chip, so that the second device layer 2 is bonded with the PCB together, thereby completing the power supply of the optical switch chip.
(9) The optical coupling mode is a grating coupling mode, and the electric packaging mode is a Wire Bonding packaging mode
Fig. 22 is a schematic structural diagram of an optical switch chip when the grating coupling mode and the Wire Bonding packaging mode are combined, and as shown in fig. 22, light in two polarization states output from an optical fiber is respectively coupled to a grating coupler of the first device layer 1 and a grating coupler of the second device layer 2, so that optical coupling to the optical switch chip is completed. In the optical switch chip, the electrodes of the second device layer 2 are connected with a ceramic transfer shell (or other types of transfer devices) one by using metal leads, and the ceramic transfer shell is connected with a PCB (printed circuit board) driving board.
It should be noted that, for the sake of simplicity, only a portion of the electrodes are shown in fig. 22 to be connected to the ceramic transition housing, and in practice, all the electrodes need to be connected to the ceramic transition housing.
The above description is provided for the purpose of illustration and not for the purpose of limitation, and any modifications, equivalents, improvements, etc. made within the spirit and principles of the present application should be included within the scope of the present application.
Claims (10)
1. An optical switch chip, comprising: a first device layer, a second device layer and a first bottom layer;
the first device layer is connected with the first bottom layer;
an optical switch matrix, N optical coupling devices and a plurality of electrodes are distributed on the first device layer and the second device layer, wherein N is an integer greater than 1; in the first device layer and the second device layer, the functions and the structures of the optical switch matrixes are the same, the number of the optical couplers is the same, and the number of the electrodes is the same;
the first device layer and the second device layer are bonded together through vertical welding of the electrode of the first device layer and the corresponding electrode of the second device layer;
the N photo-coupling devices of the first device layer are located at the same position on the first device layer as the N photo-coupling devices of the second device layer are located on the second device layer.
2. The optical switch chip of claim 1, wherein the electrodes of the first device layer are connected to the electrodes of the second device layer in a one-to-one correspondence.
3. The optical switch chip of claim 2, wherein the optical switch matrix of the first device layer and the optical switch matrix of the second device layer are both single polarization optical switch matrices.
4. The optical switch chip of claim 1, wherein the optical coupling device of the first device layer and the optical coupling device of the second device layer are both edge couplers.
5. The optical switch chip of claim 4,
the edge coupler of the first device layer and the edge coupler of the second device layer are respectively coupled with two single-polarization optical signals separated by the birefringent crystal;
the birefringent crystal is located outside the optical switch chip and is used for separating two mutually orthogonal optical signals transmitted by the optical fiber into two single-polarization optical signals.
6. The optical switch chip of claim 4,
the edge coupler of the first device layer is used for coupling a first single-polarization optical signal transmitted by a polarization-maintaining optical fiber connected with the edge coupler of the first device layer;
the edge coupler of the second device layer is used for coupling a second single-polarization optical signal transmitted by the polarization-maintaining optical fiber connected with the edge coupler of the second device layer.
7. The optical switch chip of claim 1, wherein the optical coupling device of the first device layer and the optical coupling device of the second device layer are both grating couplers;
the grating coupler of the first device layer and the grating coupler of the second device layer are respectively coupled with two single-polarization optical signals.
8. The optical switch chip according to any of claims 2-7, further comprising: a second bottom layer;
the second bottom layer is connected with the second device layer;
the electrode of the first device layer is connected with a driving circuit through a through hole arranged on the first device layer.
9. The optical switch chip according to any of claims 2 to 7,
and the electrode of the second device layer is bonded with the driving circuit through vertical welding.
10. The optical switch chip according to any of claims 2-7, wherein the electrodes of the second device layer are connected to the driving circuit through metal wires.
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| US5943464A (en) * | 1997-02-07 | 1999-08-24 | Khodja; Salah | Nonlinear optical device including poled waveguide and associated fabrication methods |
| CN2571076Y (en) * | 2002-09-13 | 2003-09-03 | 中国科学院上海微系统与信息技术研究所 | Two-dimensional optical switch matrix made by piezoelectric driver |
| JP2006084501A (en) * | 2004-09-14 | 2006-03-30 | Fujitsu Ltd | Optical module |
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