INTEGRATED OPTICAL TRANSCEIVER APPARATUS AND OPTICAL LINE TERMINAL

An integrated optical transceiver apparatus and an OLT are provided. A first splitter and a second splitter are integrated into a PLC structure of the apparatus. The first splitter is configured to output signal light of a first wavelength and signal light of a second wavelength, and output signal light of a third wavelength and signal light of a fourth wavelength. The second splitter is configured to separate the signal light of the third wavelength and the signal light of the fourth wavelength, output the signal light of the third wavelength, and output the signal light of the fourth wavelength. A first optical detector and a second optical detector are disposed on the PLC structure, where the first optical detector and the second optical detector are configured to convert, into electrical signals, the signal light output by the second splitter and the signal light output by the second splitter.

TECHNICAL FIELD

This disclosure relates to the field of optical communications technologies, and in particular, to an integrated optical transceiver apparatus and an optical line terminal.

BACKGROUND

An optical transceiver apparatus is an important component in an optical communications system, and is used to implement sending and receiving of signal light. To simplify a packaging process of the optical transceiver apparatus, a plurality of devices in the optical transceiver apparatus may be integrated.

In a related technology, the integrated optical transceiver apparatus includes an optical device and an electrical device. The optical device includes a bidirectional splitter, and the electrical device includes an optical detector. The bidirectional splitter is used to output signal light of a first wavelength from a laser to an optical fiber, to implement sending of the signal light, and output signal light of a second wavelength from the optical fiber to the optical detector, so that the optical detector converts the received signal light into an electrical signal, to implement receiving of the signal light. The bidirectional splitter is integrated into a planar lightwave circuit (PLC) structure, and the optical detector is fixed on the planar lightwave circuit structure.

Signal light sent by the optical transceiver apparatus and signal light received by the optical transceiver each have a single wavelength, which cannot meet development requirements of an optical communications network.

SUMMARY

This disclosure provides an integrated optical transceiver apparatus and an optical line terminal, so as to implement sending of dual-wavelength signal light and receiving of dual-wavelength signal light. The technical solutions are as follows.

According to one aspect, an integrated optical transceiver apparatus is provided. The integrated optical transceiver apparatus includes a PLC structure and an electrical device. An optical device is integrated in the PLC structure, and the optical device includes a first splitter and a second splitter. An electrical device is disposed on the PLC structure, and the electrical device includes a first optical detector and a second optical detector.

The first splitter has a first end, a second end, and a third end. The first splitter is configured to output, from the second end of the first splitter to an optical fiber, signal light of a first wavelength and signal light of a second wavelength that are received by the first end of the first splitter, so as to implement sending of the signal light of the first wavelength and the signal light of the second wavelength.

The first splitter is further configured to output, from the third end of the first splitter, signal light of a third wavelength and signal light of a fourth wavelength that are received by the second end of the first splitter from the optical fiber. The second splitter has a first end, a second end, and a third end. The first end of the second splitter is connected to the third end of the first splitter. The second splitter is configured to separate the signal light of the third wavelength and the signal light of the fourth wavelength that are output from the third end of the first splitter, output the signal light of the third wavelength from the second end of the second splitter, and output the signal light of the fourth wavelength from the third end of the second splitter. The first optical detector is configured to convert, into an electrical signal, the signal light of the third wavelength that is output by the second end of the second splitter, and the second optical detector is configured to convert, into an electrical signal, the signal light of the fourth wavelength that is output by the third end of the second splitter, so as to implement receiving the signal light of the third wavelength and the signal light of the fourth wavelength.

It can be learned that the signal light sent by the integrated optical transceiver apparatus provided in this embodiment of this disclosure is dual-wavelength signal light, and the received signal light is also dual-wavelength signal light. Signal light of different wavelengths can carry more information, thereby improving capacity of an optical communications system and adapting to development requirements of an optical communications network. In addition, in this embodiment of this disclosure, during assembly of the optical transceiver apparatus, the electrical device only needs to be attached to the PLC structure because the optical device is integrated into the PLC structure, thereby simplifying an assembly process. In addition, the optical device and the electrical device that implement bidirectional transmission of dual-wavelength signal light are integrated into one PLC structure, so that a size of the optical transceiver apparatus is relatively small.

In this embodiment of this disclosure, the integrated optical transceiver apparatus is also referred to as a PLC chip. The first splitter has a bidirectional demultiplexing function, and is also referred to as a bidirectional (BiDi) splitter. The second splitter is also referred to as a wavelength division multiplexer (WDM).

Optionally, the first splitter is a directional coupler (DC), a Mach-Zehnder interferometer (MZI), or an arrayed waveguide grating (AWG). Bidirectional demultiplexing of dual wavelengths is implemented by using a single optical device, achieving a simple structure and high integration.

Optionally, the second splitter is an MZI or an AWG.

Optionally, the optical device further includes a spotsize converter (SSC). The SSC is connected to the second end of the first splitter, and is configured to couple, to the optical fiber, the signal light of the first wavelength and the signal light of the second wavelength that are output by the second end of the first splitter, and couple, to the second end of the first splitter, the signal light of the third wavelength and the signal light of the fourth wavelength that are output by the optical fiber. Efficiency of coupling between the integrated optical transceiver apparatus and the optical fiber can be improved by using the SSC.

In a possible embodiment, the SSC is a grating waveguide SSC. The grating waveguide SSC includes a tapered waveguide and a grating array. The tapered waveguide and the grating array are sequentially arranged in a direction away from the second end of the first splitter. The tapered waveguide is configured to perform spotsize conversion in a first direction. The grating array is configured to perform spotsize conversion in a second direction, to couple, to the optical fiber, the signal light of the first wavelength and the second wavelength and that is output by the second end of the first splitter, and couple, to the second end of the first splitter, the signal light of the third wavelength and the fourth wavelength that are output by the optical fiber, where the first direction is perpendicular to the second direction. The grating waveguide SSC can convert spot sizes simultaneously in the first direction and the second direction that are perpendicular to each other. Because the optical fiber is of a three-dimensional structure, a spot size and a shape obtained through the conversion of the spot sizes simultaneously in the first direction and the second direction that are perpendicular to each other better match a cross section of the optical fiber. This helps further improve efficiency of coupling between the integrated optical transceiver apparatus and the optical fiber.

In another possible embodiment, the SSC is a waveguide SSC, and the waveguide SSC is a tapered waveguide. A small end of the tapered waveguide is an input end, the input end is connected to an optical fiber in the PLC structure, a large end of the tapered waveguide is an output end, and the output end is coupled to an end surface of the optical fiber, so as to couple, to the optical fiber, the signal light of the first wavelength and the second wavelength that are output by the second end of the first splitter, and couple, to the second end of the first splitter, the signal light of the third wavelength and the fourth wavelength that are output by the optical fiber. The SSC formed by the tapered waveguide has a simple structure and is easy to manufacture.

The planar lightwave circuit structure has a top surface, a bottom surface, and a side surface, where the top surface is opposite to the bottom surface, the side surface is connected to the top surface and the bottom surface, and the side surface surrounds the top surface.

In a possible embodiment, the first optical detector and the second optical detector are located on the top surface, the end surface of the optical fiber is opposite to the side surface, and the planar lightwave circuit structure further has a first reflective surface and a second reflective surface. The first reflective surface is configured to reflect, to the first optical detector, the signal light of the third wavelength that is output by the second end of the second splitter. The second reflective surface is configured to reflect, to the second optical detector, the signal light of the fourth wavelength that is output by the third end of the second splitter. The PLC structure using a silicon dioxide platform facilitates coupling to an optical fiber and has low costs. In addition, the PLC structure is insensitive to polarization, helping improve light transmission efficiency. In addition, the electrical device is disposed on the top surface of the PLC structure, and the electrical device only needs to be attached to the top surface. This is easy to implement, and further helps reduce a size of the integrated optical transceiver apparatus in a direction parallel to the top surface of the PLC structure.

In another possible embodiment, the first optical detector and the second optical detector are located on the side surface, and the end surface of the optical fiber is opposite to the side surface. The electrical device is disposed on the side surface of the PLC structure, helping reduce a height of the integrated optical transceiver apparatus in a direction perpendicular to the top surface of the PLC structure.

In a possible embodiment, the PLC structure is a PLC structure based on a silicon dioxide platform with a low refractive index difference. The PLC structure based on the silicon dioxide platform with the low refractive index difference includes a first silicon dioxide layer, a second silicon dioxide layer, and a third silicon dioxide layer that are sequentially stacked. A refractive index of the second silicon dioxide layer is greater than a refractive index of the first silicon dioxide layer, the refractive index of the second silicon dioxide layer is greater than a refractive index of the third silicon dioxide layer, and the optical device is integrated into the second silicon dioxide layer.

In another possible embodiment, the PLC structure is based on a silicon-on-insulator (silicon on insulator, SOI) platform. For example, the PLC structure based on the SOI platform includes a silicon substrate, a semiconductor insulation layer, and a silicon layer, and the insulation layer and the silicon layer are sequentially stacked on the silicon substrate. The optical device is integrated into the silicon layer. For example, the insulation layer of the semiconductor is a silicon dioxide layer.

Optionally, the electrical component further includes two transimpedance amplifiers (TIA). One of the two TIAs is connected to the first optical detector, and the other of the two TIAs is connected to the second optical detector. The TIAs are configured to perform low-noise amplification of a received electrical signal with a specific strength, so as to increase a ratio of an optical signal to noise.

Optionally, both the first optical detector and the second optical detector are avalanche photodiodes (APD) or positive-intrinsic-negative (PIN) photodiodes (PD).

In some examples, the integrated optical transceiver apparatus further includes a light source, and the light source is configured to provide the signal light of the first wavelength and the signal light of the second wavelength. The light source is also integrated into the PLC structure. For example, an output end of the light source is attached to a side surface of the PLC structure, to further improve an integration degree of the optical transceiver apparatus.

Optionally, the light source includes a first laser, a second laser, and an optical multiplexer. The first laser is configured to transmit the signal light of the first wavelength, the second laser is configured to transmit the signal light of the second wavelength, and the optical multiplexer is configured to combine the signal light of the first wavelength and the signal light of the second wavelength into one signal and output the signal to the first end of the first splitter. During implementation, all components in the light source are first assembled together, and then are attached to the PLC structure, so that the light source and the PLC structure are integrated together.

Optionally, the first wavelength belongs to a long-wavelength band, the second wavelength belongs to a short-wavelength band, and the third wavelength and the fourth wavelength belong to an original band.

In another aspect, an optical line terminal (OLT) is provided, where the OLT includes a plurality of optical modules, and any optical module includes any one of the integrated optical transceiver apparatuses described above.

REFERENCE NUMERALS

1: light source;2: optical fiber;10: PLC structure;10a: top surface;10b: bottom surface;10c: side surface;101: first silicon dioxide layer;102: second silicon dioxide layer;103: third silicon dioxide layer;11: first splitter;11a: first end of the first splitter;11b: second end of the first splitter;11c: third end of the first splitter; and11d: fourth end of the first splitter;111. DC;112. MZI;113. AWG;12: second splitter;12a: first end of the second splitter;12b: second end of the second splitter;12c: third end of the second splitter;121: AWG;122: MZI;13: SSC;131: tapered waveguide;132: grating array;132a: strip structure;133b: filling structure;141: first waveguide;142: second waveguide;143: third waveguide;144: fourth waveguide;145: fifth waveguide;144a: first reflective surface;145a: second reflective surface;21a: first optical detector;21b: second optical detector; and22: TIA.

DESCRIPTION OF EMBODIMENTS

FIG.1is a schematic diagram of a structure of an integrated optical transceiver apparatus according to an embodiment of this disclosure. As shown inFIG.1, the integrated optical transceiver apparatus includes a PLC structure10and an electrical device.

An optical device is integrated in the PLC structure10, and the optical device includes a first splitter11and a second splitter12. The first splitter11has a first end11a, a second end11b, and a third end11c. The first splitter11is configured to output, from the second end11bof the first splitter11to an optical fiber2, signal light of a first wavelength and a second wavelength that are received by the first end11aof the first splitter11, and output, from the third end11cof the first splitter11, signal light of a third wavelength and signal light of a fourth wavelength that are received by the second end11bof the first splitter11from the optical fiber2. The second splitter12has a first end12a, a second end12b, and a third end12c. The first end12aof the second splitter12is connected to the third end11cof the first splitter11. The second splitter12is configured to separate the signal light of the third wavelength and the signal light of the fourth wavelength that are output from the third end11cof the first splitter11, output the signal light of the third wavelength from the second end12bof the second splitter12, and output the signal light of the fourth wavelength from the third end12cof the second splitter12.

The electrical device is located on the PLC structure10, and the electrical device includes a first optical detector21aand a second optical detector21b. The first optical detector21ais configured to convert, into an electrical signal, the signal light of the third wavelength that is output by the second end12bof the second splitter12. The second optical detector21bis configured to convert, into an electrical signal, the signal light of the fourth wavelength that is output by the third end12cof the second splitter12.

Optionally, the first splitter11is a DC, an MZI, or an AWG. Optionally, the second splitter12is an MZI or an AWG. Optionally, both the first optical detector21aand the second optical detector21bare APDs or PIN-type PDs.

Optionally, the optical device further includes an SSC13. The SSC13is connected to the second end11bof the first splitter11. The SSC13is configured to couple, to the optical fiber2, the signal light of the first wavelength and the signal light of the second wavelength that are output by the second end11bof the first splitter11, and couple, to the second end11bof the first splitter11, the signal light of the third wavelength and the signal light of the fourth wavelength that are output by the optical fiber2. Optionally, the SSC13is any one of the following: a grating waveguide SSC or a waveguide SSC.

In a possible embodiment, the PLC structure10is based on a silicon dioxide platform. The PLC structure based on the silicon dioxide platform includes a first silicon dioxide layer, a second silicon dioxide layer, and a third silicon dioxide layer that are sequentially stacked. A refractive index of the second silicon dioxide layer is greater than a refractive index of the first silicon dioxide layer, and the refractive index of the second silicon dioxide layer is greater than a refractive index of the third silicon dioxide layer. The optical device is integrated into the second silicon dioxide layer. The PLC structure using a silicon dioxide platform facilitates coupling to an optical fiber and has low costs. In addition, the PLC structure is insensitive to polarization, helping improve light transmission efficiency.

For example, in the PLC structure based on the silicon dioxide platform, the second silicon dioxide layer is used as a core layer, the first silicon dioxide layer and the third silicon dioxide layer are used as cladding layers, and a refractive index difference between the core layer and a cladding layer is set according to a requirement, for example, to be within 3%, which means that a ratio of the refractive index difference between the core layer and the cladding layer to the refractive index of the cladding layer is less than 3%.

In another possible embodiment, the PLC structure10is based on an SOI platform. For example, the PLC structure based on the SOI platform includes a silicon substrate, an insulation layer, and a silicon layer, and the insulation layer and the silicon layer are sequentially stacked on the silicon substrate. The optical device is integrated into the silicon layer. For example, the insulation layer is a silicon dioxide layer.

It should be noted that a material used for the PLC structure is not limited in this disclosure. In addition to the silicon dioxide platform and the SOI platform, another platform may be used for embodiment.

Optionally, the electrical device further includes two TIAs22. One of the two TIAs22is connected to the first optical detector21a, and the other of the two TIAs22is connected to the second optical detector21b. The TIA22is configured to perform low-noise amplification with a specific intensity on an electrical signal that is output by a corresponding optical detector, so as to improve a ratio of an optical signal to noise.

It should be noted that in this embodiment of this disclosure, any combination of a type of the first splitter, a type of the second splitter, and a type of the SSC falls within the protection scope of this disclosure. This is not limited in this disclosure.

FIG.2is a schematic diagram of a working principle of the integrated optical transceiver apparatus shown inFIG.1. As shown inFIG.2, signal light of a first wavelength λ1 and a second wavelength λ2 that are emitted by a light source1are transmitted to the first splitter11, and are output to the optical fiber2by using the first splitter11. The optical fiber2outputs signal light of a third wavelength λ3 and signal light of a fourth wavelength λ4 to the first splitter11. The first splitter11outputs the signal light of the third wavelength λ3 and the signal light of the fourth wavelength λ4 to the second splitter12. The second splitter12separates the signal light of the third wavelength λ3 from the signal light of the fourth wavelength λ4, and outputs the signal light of the third wavelength λ3 to the first optical detector21aand the signal light of the fourth wavelength λ4 to the second optical detector21b.

Optionally, the first wavelength λ1 belongs to a long wavelength (L) band, the second wavelength λ2 belongs to a short wavelength (S) band, and the third wavelength λ3 and the fourth wavelength belong to an original (0) band. In the field of optical communications, the L band is from 1565 nm to 1625 nm, the S band is from 1460 nm to 1530 nm, and the 0 band is from 1260 nm to 1360 nm. Therefore, in this embodiment of this disclosure, multi-band signal light transmission can be implemented.

For example, the first wavelength λ1 is 1577 nm, the second wavelength λ2 is 1490 nm, the third wavelength λ3 is 1270 nm, and the fourth wavelength λ4 is 1310 nm. The first wavelength λ1 and the third wavelength λ3 are service wavelengths of a 10-gigabit-capable passive optical network (XGPON) system, and the second wavelength λ2 and the fourth wavelength λ4 are service wavelengths of a gigabit-capable passive optical network (GPON) system. Therefore, this can adapt to a development requirement of an optical communications network.

FIG.3is a schematic diagram of a top view of a structure of another integrated optical transceiver apparatus according to an embodiment of this disclosure. As shown inFIG.3, the integrated optical transceiver apparatus includes a PLC structure10, and an optical device is integrated in the PLC structure10. The optical device includes a first splitter11and a second splitter12.

The first splitter11is a DC111, and the DC111is a four-port device. Therefore, the first splitter11has a first end11a, a second end11b, a third end11c, and a fourth end11d.

The first end11aof the first splitter11is connected to one end of a first waveguide141, and the other end of the first waveguide141extends to a side surface of the PLC structure10, to be coupled to a light source. The first waveguide141can transfer signal light of a first wavelength and signal light of a second wavelength that are from the light source to the first end11aof the first splitter11.

The second end11bof the first splitter11is connected to one end of a second waveguide142, and the other end of the second waveguide142is coupled to an optical fiber2. The second waveguide142can transfer signal light of a third wavelength and signal light of a fourth wavelength that are from an optical fiber3to the second end11bof the first splitter11.

The third end11cof the first splitter11is connected to one end of a third waveguide143, and the other end of the third waveguide143is connected to a first end12aof the second splitter12. The third waveguide143can transfer the optical signal that is output by the third end11cof the first splitter11to the first end12aof the second splitter12.

The fourth end11dof the first splitter11is vacant, and is not connected to another optical device.

FIG.4is a schematic diagram of a structure of a DC. With reference toFIG.4, the DC111includes two branches: a first branch111aand a second branch111b. Two ends of the first branch111aare a first end11aand a second end11bof a first splitter11, and two ends of the second branch111bare a third end11cand a fourth end11dof the first splitter11. The middle of the first branch111aand the middle of the second branch111bare coupled to each other.

As shown in part (a) ofFIG.4, signal light of a first wavelength and signal light of a second wavelength enter the first branch111afrom the first end11aof the first splitter11, are coupled from the middle of the first branch111ato the second branch111b, are transmitted along the middle of the second branch111b, are coupled from the second branch111bto the first branch111a, continue to be transmitted along the first branch111a, and are finally output from the second end11bof the first splitter11.

As shown in part (b) ofFIG.4, signal light of a third wavelength and signal light of a fourth wavelength enter the first branch111afrom the second end11bof the first splitter11, are coupled from the middle of the first branch111ato the second branch111b, are then transmitted along the second branch111b, and finally are output from the third end11cof the first splitter11.

It should be noted that the coupling process of the signal light shown inFIG.4is merely an example. In some embodiments, the signal light may be coupled between the first branch111aand the second branch111bfor a plurality of times. A quantity of coupling times is not limited in this embodiment of this disclosure, provided that it can be ensured that the signal light of the first wavelength and the signal light of the second wavelength enter the first branch111afrom the first end11aof the first splitter11and are finally output from the second end11bof the first splitter11, and provided that it can be ensured that the signal light of the third wavelength and the signal light of the fourth wavelength enter the first branch111afrom the second end11bof the first splitter11, and are finally output from the third end11cof the first splitter11.

During implementation, parameters such as lengths and a spacing of branches of the DC111are designed, so that signal light that is in a first band and that is input from the first end11aof the first splitter11to the DC111can be coupled from the first branch111ato the second branch111b, then coupled from the second branch111bto the first branch111a, and output from the second end11bof the first splitter11. In addition, signal light that is in the second band and that is input from the second end11bof the first splitter11to the DC111can be coupled from the first branch111ato the second branch111band output from the third end11cof the first splitter11. In this way, both the signal light of the first wavelength and the signal light of the second wavelength that are in the first band can be input from the first end11aof the first splitter11and output from the second end11bof the first splitter11, and both the signal light of the third wavelength and the signal light of the fourth wavelength that are in the second band can be input from the second end11bof the first splitter11and output from the third end11cof the first splitter11. Therefore, a bidirectional demultiplexing function is implemented by using the DC111.

Herein, both the first band and the second band belong to continuous wavelength ranges, the first band includes an L band and an S band, the second band is an O band, and there is no intersection between a first bandwidth and a second bandwidth.

For example, in the embodiment shown inFIG.3, the second splitter12is an AWG121. When the third wavelength and the fourth wavelength belong to the O band, a length of each waveguide and a spacing between waveguides in arrayed waveguides of the AWG are designed, so that the AWG121can implement low-crosstalk demultiplexing on the signal light of the third wavelength and the signal light of the fourth wavelength.

FIG.5is a schematic diagram of a structure of an AWG. As shown inFIG.5, the AWG121includes at least one input waveguide121a, a first planar waveguide121b, a plurality of output waveguides121c, a second planar waveguide121d, and an arrayed waveguide121e. The plurality of input waveguides121aare connected to the first planar waveguide121b, the plurality of output waveguides121care connected to the second planar waveguide121d, and the arrayed waveguide121eis connected between the first planar waveguide121band the second planar waveguide121d. The arrayed waveguide121eis a group of waveguides having an equal length difference, and there is an equal length difference between any two adjacent waveguides in the arrayed waveguide121e.

It should be noted that the black block-shaped areas inFIG.5are formed due to an excessive density of the arrayed waveguide121e, and do not represent another structure.

After signal light including a plurality of wavelengths is input from any input waveguide121ato the first planar waveguide121b, the first planar waveguide121ballocates, based on a basically average optical power, the signal light including the plurality of wavelengths to each waveguide in the arrayed waveguide121e. Because lengths of a plurality of waveguides in the arrayed waveguide121eare different, phase delays generated when signal light of different wavelengths arrives at the second planar waveguide121dthrough the arrayed waveguide121eare also different, and the signal light of the different wavelengths is converged in the second planar waveguide121d. Based on the optical interference principle, the signal light of the different wavelengths is focused at different positions. Ports of the plurality of output waveguides121care located at focus positions corresponding to the signal light of the different wavelengths, so that the plurality of output waveguides121ccan output the signal light of corresponding wavelengths, and different output waveguides121ccorrespond to signal light of different wavelengths. Through this process, the AWG121can implement a function of demultiplexing signal light of different wavelengths.

In this embodiment of this disclosure, the first end12aof the second splitter12is one of the plurality of input waveguides121a, and the second end12band the third end12cof the second splitter12are both output waveguides121c. The first end12aof the second splitter12is connected to the third end11cof the first splitter11by using the third waveguide143. Therefore, the first end12aof the second splitter12receives the signal light of the third wavelength and the signal light of the fourth wavelength that are output from the third end11cof the first splitter11. After separating the signal light of the third wavelength and the signal light of the fourth wavelength, the second splitter12outputs the signal light of the third wavelength from the second end12bof the second splitter12, and outputs the signal light of the fourth wavelength from the third end12cof the second splitter12.

As shown inFIG.3, the integrated transceiver further includes an electrical device. The electrical device includes the first optical detector21aand the second optical detector21b. The second end12bof the second splitter12is connected to one end of a fourth waveguide144, the other end of the fourth waveguide144is coupled to the first optical detector21a, and the fourth waveguide144can couple the signal light of the third wavelength to the first optical detector21a. The third end12cof the second splitter12is connected to one end of a fifth waveguide145, the other end of the fifth waveguide145is coupled to the second optical detector21b, and the fifth waveguide145can couple the signal light of the fourth wavelength to the second optical detector21b.

Refer toFIG.3again. The optical device10further includes an SSC13. The other end of the second waveguide142is connected to the SSC13, and is coupled to the optical fiber2by using the SSC13. Efficient coupling between the second waveguide142and the optical fiber2can be implemented by using the SSC13. As shown inFIG.3, the SSC13is a grating waveguide SSC.

FIG.6is a schematic diagram of an enlarged structure of a grating waveguide SSC. As shown inFIG.6, the grating waveguide SSC includes a tapered waveguide131and a grating array132. The tapered waveguide131is configured to perform spotsize conversion in a first direction X, the grating array132is configured to perform spotsize conversion in a second direction Y, and the first direction X is perpendicular to the second direction Y. In this embodiment of this disclosure, the first direction X is parallel to a propagation plane of signal light, and the second direction Y is perpendicular to the propagation plane of the signal light. The propagation plane of the signal light is a plane on which the foregoing waveguides (for example, the first waveguide141to the fourth waveguide144) and the SSC13are located.

The tapered waveguide131includes a small end and a large end. The small end is connected to the second waveguide142, and the large end is disposed closer to the optical fiber2than the small end. A size of the tapered waveguide changes, so that a spotsize size gradually increases from the small end to the large end along an extension direction of the tapered waveguide, thereby implementing spotsize conversion in the first direction X.

The grating array132is located between the large end and the optical fiber2, and includes a plurality of strip structures132adisposed in parallel and filling structures132bfilled between the strip structures132a. The strip structures132aand the second waveguide142are on a same layer and are formed by using a same material. A refractive index of the filling structure132bis different from a refractive index of the strip structures132a. For example, a length of each strip structure132ais equal to a length of a side edge of the large end of the tapered waveguide131. The signal light is transferred to the grating array132, and when the signal light is propagated along the grating array132, a binding capability of the grating array132to the signal light gradually decreases, so that a spotsize size increases in the second direction Y, thereby implementing spotsize conversion in the second direction Y.

A size and a shape of the spotsize obtained through the conversion of the spotsize size in both the first direction X and the second direction Y that are perpendicular to each other better match a cross section of an optical fiber, helping further improve coupling efficiency between the second waveguide and the optical fiber.

FIG.7is a schematic diagram of a side view of a structure of the integrated optical transceiver apparatus shown inFIG.3. Optionally, as shown inFIG.7, a PLC structure10includes a first silicon dioxide layer101, a second silicon dioxide layer102, and a third silicon dioxide layer103that are sequentially stacked. A refractive index of the second silicon dioxide layer102is greater than a refractive index of the first silicon dioxide layer101, the refractive index of the second silicon dioxide layer102is greater than a refractive index of the third silicon dioxide layer103, and the optical device10is integrated into the second silicon dioxide layer102.

The PLC structure10has a top surface10a, a bottom surface10b, and a side surface10c. The top surface10ais opposite to the bottom surface10b, the side surface10cis connected between the top surface10aand the bottom surface10b, and the side surface10csurrounds the top surface10a. The optical device20is located on the top surface10aof the PLC structure10. An electrical device is disposed on the top surface of the PLC structure, and the electrical device only needs to be attached to the top surface. This is easy to implement, and further helps reduce a size of the integrated optical transceiver apparatus in a direction parallel to the top surface of the PLC structure. The top surface is an outer surface of the first silicon dioxide layer or the third silicon dioxide layer in each stacking direction of the PLC structure.

As shown inFIG.7, an end surface of the optical fiber2is located on the side surface10c. The first optical detector21aand the second optical detector are located on the top surface10a. For example, the first optical detector21aand the second optical detector are mounted on the top surface10aof the PLC structure10in an inverted manner. The PLC structure10further has a first reflective surface144aand a second reflective surface145a. The first reflective surface144ais configured to reflect, to the first optical detector21a, the signal light of the third wavelength that is output by the second end12bof the second splitter12, and the second reflective surface145ais configured to reflect, to the second optical detector21b, the signal light of the fourth wavelength that is output by the third end12cof the second splitter12.

In this embodiment of this disclosure, the first reflective surface144ais an end surface that is of the fourth waveguide144and that is far away from the second splitter12, and the second reflective surface145ais an end surface that is of the fifth waveguide145and that is far away from the second splitter12.

For example, an included angle between the top surface10aand the first reflective surface144aand the included angle between the top surface10aand the second reflective surface145ameet the following relationship:

θ1 is the included angle, and θ0 is the total reflection angle. For example, the included angle is 38 to 42 degrees.

In this embodiment, a propagation direction of the signal light of the third wavelength in the fourth waveguide144is parallel to the top surface10aof the PLC structure10. Therefore, an incident angle of the signal light of the third wavelength on the first reflective surface144ais equal to the difference between 90 and θ1. When the incident angle is greater than or equal to the total reflection angle, the signal light of the third wavelength is totally reflected on the first reflective surface144a.

In this embodiment, a part of a side edge that is of the bottom surface10band that is connected to the side surface10cof the PLC structure10is cut off, and end surfaces of the fourth waveguide144and the fifth waveguide145are polished, so that end surfaces of one end of the fourth waveguide144and the fifth waveguide145that are away from the second splitter12are oblique, and an included angle between the end surfaces and the top surface10ais less than the total reflection angle. In this way, the first reflective surface144aand the second reflective surface145acan be obtained, and there is no need to add another reflection structure to the PLC structure10, making the structure simple.

FIG.8is a schematic diagram of an optical path obtained after signal light of a third wavelength is reflected by a first reflective surface. As shown inFIG.8, after the signal light of the third wavelength is reflected by a first reflective surface144a, the signal light passes through a third silicon dioxide layer103, and is coupled to a window of a first optical detector21a.

A propagation path and a principle of signal light of a fourth wavelength reflected on a second reflective surface are the same as those of the signal light of the third wavelength, and details are not described herein again.

With reference toFIG.3andFIG.7, the integrated optical transceiver apparatus further includes two TIAs22. One TIA22is connected to the first optical detector21a, and the other TIA22is connected to the second optical detector21b. The TIA22is also located on the top surface10aof the PLC structure10. For example, the TIA22is mounted on the top surface10aof the PLC structure10in an inverted manner.

FIG.9is a top-view schematic diagram of a structure of another integrated optical transceiver apparatus according to an embodiment of this disclosure. As shown inFIG.9, a difference from the integrated optical transceiver apparatus shown inFIG.3lies in that, in the integrated optical transceiver apparatus shown inFIG.9, an MZI112is used as a first splitter11, an MZI122is used as a second splitter12, and a tapered waveguide (namely, a waveguide SSC) is used as an SSC13.

FIG.10is a schematic diagram of a structure of an MZI. As shown inFIG.10, the MZI122includes a first coupler122a, a second coupler122b, and two arms122cconnected between the first coupler122aand the second coupler122b, where lengths of the two arms122care unequal. The first end12aof the second splitter12is connected to the first coupler122a, and the signal light of the third wavelength and the signal light of the fourth wavelength that are received from the first end12aof the second splitter12are evenly distributed to the two arms122cthrough the first coupler122a. Because lengths of the two arms122care not equal, a phase difference is generated when the signal light transmitted by the two arms122carrives at the second coupler122b.

Both the second end12band the third end12cof the second splitter12are connected to the second coupler122b. At the second end12bof the second splitter12, the signal light of the third wavelength meets a constructive interference condition, the optical signal light of the fourth wavelength meets a destructive interference condition, and the second end12bof the second splitter12outputs the signal light of the third wavelength. However, at the third end12cof the second splitter12, the signal light of the fourth wavelength meets the constructive interference condition, the optical signal light of the third wavelength meets the destructive interference condition, and the third end12cof the second splitter12outputs the signal light of the fourth wavelength.

However, for the MZI112used as the first splitter11, a structure and a principle are the same as those of the MZI122, and a difference lies in that parameters such as lengths and a spacing of the two arms are different, so that the MZI112can output, from the second end11bof the first splitter11, signal light that is in a first band and that is input from the first end11aof the first splitter11to the MZI112, and output, from the third end11cof the first splitter11, signal light that is in a second band and that is input from the second end11bof the first splitter11to the MZI112. In this way, a bidirectional demultiplexing function is implemented by using the MZI112.

Herein, both the first band and the second band include continuous wavelength ranges, the first band includes an L band and an S band, the second band is an O band, and there is no intersection between a first bandwidth and a second bandwidth.

In the integrated optical transceiver apparatus shown inFIG.9, the second end12bof the second splitter12is coupled to an optical fiber2by using a tapered waveguide. A small end of the tapered waveguide is connected to a second waveguide142, and a large end of the tapered waveguide is coupled to an end surface of the optical fiber2. The SSC formed by the tapered waveguide has a simple structure and is easy to manufacture.

FIG.11is a schematic diagram of a side view of a structure of the integrated optical transceiver apparatus shown inFIG.9. In the structure shown inFIG.11, similar to the integrated optical transceiver apparatus shown inFIG.3andFIG.7, an end surface that is of a waveguide connected to the second end12bof the second splitter12and that is far away from the second end12bof the second splitter12is a first reflective surface144a, and an end surface that is of a waveguide connected to the third end12cof the second splitter12and that is far away from the third end12cof the second splitter12is a second reflective surface145a.

FIG.12is a schematic diagram of a top view of a structure of another integrated optical transceiver apparatus according to an embodiment of this disclosure. As shown inFIG.12, a difference from the integrated optical transceiver apparatus shown inFIG.3lies in that, in the integrated optical transceiver apparatus shown inFIG.12, an AWG113is used as a first splitter11.

When the AWG113is used as the first splitter, a structure and a principle of the AWG113are similar to those of the AWG121shown inFIG.5. Parameters such as lengths and a spacing of waveguides in an arrayed waveguide are designed, so that after being input into the AWG113from a first end11aof the first splitter11, signal light in a first band passes through a first planar waveguide and the arrayed waveguide, and is output, based on an interference principle of light, from a second end11bof the first splitter11connected to a second planar waveguide, and after being input into the AWG113from the second end11bof the first splitter11, signal light in a second band passes through a second planar waveguide and the arrayed waveguide, and is output, based on the interference principle of light, from a third end11cof the first splitter11, so as to implement a bidirectional demultiplexing function by using the AWG113.

Herein, both the first band and the second band belong to continuous wavelength ranges, the first band includes an L band and an S band, the second band is an O band, and there is no intersection between a first bandwidth and a second bandwidth.

FIG.13is a schematic diagram of a side view of a structure of the integrated optical transceiver apparatus shown inFIG.12. As shown inFIG.13, an electrical device is located on a side surface10cof a PLC structure10. For example, a first optical detector21a, a second optical detector21b, and a TIA22are fastened on a same substrate, and the first optical detector21aand the second optical detector21bare attached to the side surface10cof the PLC structure10by using a substrate, so as to integrate the electrical device and the PLC structure10.

For example, the PLC structure10is a cuboid, and an optical fiber2and the electrical device are respectively located on two opposite side surfaces10cof the cuboid. One end of a fourth waveguide144and one end of a fifth waveguide145are located on the side surface10c, light of a third wavelength is directly emitted from an end surface of the fourth waveguide144to the first optical detector21a, and light of a fourth wavelength is directly emitted from an end surface of the fifth waveguide145to the second optical detector21b.

Alternatively, in another embodiment, the optical fiber2and the electrical device are located on two adjacent side surfaces of the cuboid, or the optical fiber2and the electrical device are located on a same side surface of the cuboid.

In some examples, signal light of a first wavelength and signal light of a second wavelength are provided by a light source outside the integrated optical transceiver apparatus. In other examples, the signal light of the first wavelength and the signal light of the second wavelength are provided by a light source inside the integrated optical transceiver apparatus. In this case, the integrated optical transceiver apparatus provided in this embodiment of this disclosure further includes a light source. The light source is configured to provide the signal light of the first wavelength and the signal light of the second wavelength. The light source is disposed on the PLC structure.

Optionally, the light source includes a first laser, a second laser, and an optical multiplexer. The first laser is configured to transmit the signal light of the first wavelength, the second laser is configured to transmit the signal light of the second wavelength, and the optical multiplexer is configured to combine the signal light of the first wavelength and the signal light of the second wavelength into one signal and output the signal to the first end of the first splitter.

Optionally, the light source is adhered to the side surface10cof the PLC structure10, so as to be integrated on the PLC structure10.

For example, the first laser and the second laser are semiconductor lasers. The optical multiplexer includes but is not limited to a PLC-type optical multiplexer, provided that the signal light transmitted by the first laser and the second laser can be combined into one signal and provided to the first end of the first splitter.

It should be noted that, in some examples, the integrated optical transceiver apparatus provided in this embodiment of this disclosure is further configured to send and receive signal light of a plurality of wavelengths. For example, the first splitter is further configured to output, from the second end of the first splitter, the signal light of the fifth wavelength that is received from the first end of the first splitter to the optical fiber, and output, from a third end of the first splitter, the signal light of the fifth wavelength that is from the optical fiber and that is received from the second end of the first splitter together with the signal light of the first wavelength and the signal light of the second wavelength. The second splitter is further configured to: separate the signal light of the fifth wavelength that is output from the third end of the first splitter from the signal light of the third wavelength and the fourth wavelength, and output the signal light of the fifth wavelength from a fourth end of the splitter. The electrical device further includes a third optical detector located on the PLC structure. The third optical detector receives the signal light of the fifth wavelength that is output from the fourth end of the splitter, and converts the received signal light of the fifth wavelength into an electrical signal.

In this case, the second splitter is implemented through an AWG, or is implemented through two cascaded MZIs.

An embodiment of this disclosure further provides an OLT. The OLT includes a plurality of optical modules, and any optical module includes the foregoing integrated optical transceiver apparatus. For example, the plurality of optical modules are inserted into a same card.

An embodiment of this disclosure further provides a passive optical network (passive optical network, PON) system.FIG.14is a schematic diagram of a structure of a PON system according to an embodiment of this disclosure. As shown inFIG.14, the PON system includes an OLT, an ODN, and ONUS. The OLT is connected to a plurality of ONUS through the ODN.

For an upper-layer network, the OLT is configured to implement uplink access of the PON network. For the ONUS, the OLT is configured to implement functions such as control, management, and ranging. The signal light of the first wavelength and the signal light of the second wavelength are downstream signal light, namely, signal light sent by the OLT to the ONUS, and the signal light of the third wavelength and the signal light of the fourth wavelength are upstream signal light, namely, signal light sent by the ONUS to the OLT.

Unless otherwise defined, the technical terms or scientific terms used herein should have general meanings understood by a person of ordinary skill in the art of this disclosure. The words “first”, “second”, “third”, and the like used in the specification and claims of this patent application do not indicate any order, quantity, or significance, but are merely used to distinguish between different components. Likewise, “a/an”, “one”, or the like is not intended to indicate a quantity limitation either, but is intended to indicate existing at least one. “Include”, “contain”, or the like indicates that the elements or objects before “include” or “include” cover the elements or objects listed after “include” or “contain” and their equivalents, and other elements or objects are not excluded. “Connection”, “link” or the like is not limited to a physical or mechanical connection, but may include an electrical connection, whether directly or indirectly. “Up”, “down”, “left”, “right”, “top”, “bottom”, and the like are only used to indicate a relative location relationship, and when an absolute location of a described object changes, the relative location relationship may also change accordingly.

The foregoing descriptions are merely embodiments of this disclosure, but are not intended to limit this disclosure. Any modification, equivalent replacement, or improvement made without departing from the principle of this disclosure should fall within the protection scope of this disclosure.