CN107360481B

CN107360481B - Optical module and optical line terminal

Info

Publication number: CN107360481B
Application number: CN201710677577.XA
Authority: CN
Inventors: 郑睿; 刘恭志
Original assignee: Suzhou Yirui Optoelectronics Technology Co ltd
Current assignee: Suzhou Yirui Optoelectronics Technology Co ltd
Priority date: 2017-08-09
Filing date: 2017-08-09
Publication date: 2023-04-07
Anticipated expiration: 2037-08-09
Also published as: CN107360481A

Abstract

The application provides an optical subassembly and optical line terminal, this optical subassembly includes: the device comprises a transmitting unit, a wavelength division multiplexing device, a first receiver, a second receiver, a lens element and an optical fiber interface; the emitting unit is used for emitting light rays containing a first wavelength and a second wavelength; the lens element is used for coupling light rays containing the first wavelength and the second wavelength to the optical fiber interface and carrying out beam conversion on uplink signals of the third wavelength and the fourth wavelength; the method can be compatible with the GPON and the NG-PON at the same time, and simultaneously takes account of two corresponding ONUs in the network, thereby being beneficial to smooth upgrade from the GPON system to the NG-PON system.

Description

Optical module and optical line terminal

Technical Field

The present application relates to the field of optical fiber communications, and in particular, to an optical module and an optical line terminal.

Background

The improvement of the transmission rate of the access Network needs to upgrade a Gigabit-Capable Passive Optical Network (GPON) Network to a Next Generation Passive Optical Network (NG-PON), and because they use different transmission wavelengths, a GPON and an NG-PON exist in the access Network structure at the same time during the transition period of system upgrade. The current solution is to add optical wavelength multiplexing and demultiplexing devices in the optical link, which increases the complexity of the system and is not conducive to smooth upgrade of the whole system.

At present, an external multiplexer scheme can be adopted when GPON is upgraded to NG-PON. According to the scheme, the NG-PON line card, the external wave combiner, the jump fiber and other supporting equipment are required to be added, the construction cost is high, the system construction and wiring are complex, and the management and maintenance are difficult. Another solution is to adopt a COMBO passive Optical network (COMBO-PON) mode, which is characterized in that a module of an Optical Line Terminal (OLT) is compatible with network signals of GPON and NG-PON simultaneously. Therefore, the existing network equipment and the optical fiber distribution network are borrowed, the network upgrading can be realized only by replacing the line card at the OLT end without newly adding matched equipment.

At present, an Optical component of an OLT is only a single-path transmitting and receiving structure, because wavelengths used by a GPON and an NG-PON are different, the OLT based on the existing Optical component can only singly meet communication requirements of the GPON or the NG-PON, and cannot give consideration to two Optical Network Units (ONUs) existing in a Network. If a new network structure is built in an external wavelength division multiplexer mode, the quantity ratio of GPON and NG-PON modules at an OLT end cannot be changed at will, so that the network building mode is not flexible enough, and the further upgrading is not facilitated.

Disclosure of Invention

In view of this, embodiments of the present application provide an optical component and an optical line terminal, so as to solve the technical problem that an optical component of an OLT is not compatible with a GPON and an NG-PON in the prior art, so that a network upgrade complexity is high and a cost is high.

In one aspect of an embodiment of the present application, there is provided a light assembly including: the device comprises a transmitting unit, a wavelength division multiplexing device, a first receiver, a second receiver, a lens element and an optical fiber interface; the wavelength division multiplexing device, the lens element and the optical fiber interface are sequentially arranged in the light emergent direction of the emission unit; the emitting unit is used for emitting light rays containing a first wavelength and a second wavelength; the lens element is used for coupling light rays containing the first wavelength and the second wavelength to the optical fiber interface and carrying out beam conversion on uplink signals of the third wavelength and the fourth wavelength;

the wavelength division multiplexing device realizes full transmission relative to the light with the first wavelength and the second wavelength, realizes light splitting relative to the light with the third wavelength and the fourth wavelength, and respectively couples the light with the third wavelength and the light with the fourth wavelength to the first receiver and the second receiver.

Preferably, the wavelength division multiplexing device is an interference thin film type beam splitting device including a plurality of optical filters.

In one embodiment, the interference thin film type beam splitting device includes a first filter and a second filter; the first optical filter realizes total reflection on the light with the third wavelength, couples the light with the third wavelength to the first receiver, realizes total transmission on the light with the fourth wavelength, and transmits the light with the fourth wavelength to the second optical filter; the second optical filter realizes total reflection on the light with the fourth wavelength and couples the light with the fourth wavelength to the second receiver.

Preferably, the light incident direction of the first receiver is perpendicular to the optical axis of the optical component, and the interference thin film type beam splitting device further comprises a third optical filter; the third optical filter totally reflects the light of the third wavelength totally reflected by the first optical filter again, so as to be coupled to the first receiver.

In one embodiment, the interference thin film type beam splitting device includes a first filter, a second filter, a third filter, and a fourth filter; the first optical filter realizes total reflection on the light rays with the third wavelength and the fourth wavelength; the second optical filter is calibrated in the total reflection direction of the first optical filter, the inclination angle of the second optical filter relative to the optical axis can enable the second optical filter to realize total reflection on the light with the third wavelength and to enable the light with the third wavelength to be totally reflected back to the first optical filter and to realize the second total reflection on the first optical filter, the second optical filter realizes the total transmission on the light with the fourth wavelength and couples the light with the fourth wavelength to the second receiver; the third optical filter is calibrated in the second total reflection direction of the first optical filter, and the inclination angle of the third optical filter relative to the optical axis can enable the third optical filter to realize total reflection on the light with the third wavelength; the fourth optical filter is calibrated in the total reflection direction of the third optical filter, realizes total transmission on the light with the third wavelength, and couples the light with the third wavelength to the first receiver.

In one embodiment, the interference thin film type beam splitting device includes a first filter, a second filter, a third filter, and a fourth filter; the first optical filter realizes total reflection on the light rays with the third wavelength and the fourth wavelength; the second optical filter is calibrated in the total reflection direction of the first optical filter, and the inclination angle of the second optical filter relative to the optical axis can enable the second optical filter to realize total reflection on the light rays with the third wavelength and the fourth wavelength; the third optical filter is calibrated in the total reflection direction of the second optical filter, the inclination angle of the third optical filter relative to the optical axis can realize total reflection on the third wavelength and total transmission on the fourth wavelength, and the light ray of the fourth wavelength is coupled to the second receiver; the fourth optical filter is calibrated in the total reflection direction of the third optical filter, realizes total transmission on the light with the third wavelength, and couples the light with the third wavelength to the first receiver.

In one embodiment, the transmitting unit includes: the optical filter comprises a first laser, a second laser, a fifth optical filter and an isolator; the first laser is used for emitting light rays with a first wavelength, and the second laser is used for emitting light rays with a second wavelength; the fifth optical filter realizes full transmission on the light with the first wavelength and total reflection on the light with the second wavelength, couples the light with the first wavelength and the light with the second wavelength to the same direction, and outputs the light from the emission unit after being isolated by the isolator.

Preferably, the first laser, the second laser, the first receiver and the second receiver are packaged by a TO-CAN (TO-CAN) package.

Preferably, the light emitting direction of the second laser is perpendicular to the optical axis of the optical assembly, and the included angle between the fourth optical filter and the optical axis is 45 °.

In one embodiment, the transmitting unit includes: the device comprises a first light emitting chip, a second light emitting chip, a first lens, a second lens, a total reflection prism group and an isolator; the first lens and the second lens are respectively arranged in the light emergent directions of the first light emitting chip and the second light emitting chip and are used for respectively converting emergent light of the first light emitting chip and the second light emitting chip into light rays, respectively enabling the light rays to enter the total reflection prism group to be coupled into a bundle of light rays, and outputting the bundle of light rays from the emitting unit after being isolated by the isolator.

Preferably, the package of the transmitting unit is a BOX package, and the packages of the first receiver and the second receiver are TO-CAN packages.

In one embodiment, the first wavelength of light is a downstream signal of a NG-PON, the second wavelength of light is a downstream signal of a GPON, the third wavelength of light is an upstream signal of a NG-PON, and the fourth wavelength of light is an upstream signal of a GPON.

Preferably, the optical fiber interface is a single-fiber bidirectional interface.

In another aspect of the embodiments of the present application, an Optical Line Terminal (OLT) is provided, which includes any one of the optical components in the above embodiments.

The beneficial effects of the embodiment of the application include: the optical component and the optical line terminal provided by the embodiment of the application can be compatible with a GPON and an NG-PON at the same time, and simultaneously take account of two corresponding ONUs in a network, thereby being beneficial to smooth upgrade from the GPON system to the NG-PON system, reducing the number of OLTs in the optical network and increasing the flexibility of the deployment of the COMBO-PON system.

Drawings

The above and other objects, features and advantages of the present application will become more apparent from the following description of embodiments thereof with reference to the accompanying drawings, in which:

FIG. 1 is a schematic diagram of an optical assembly provided by an embodiment of the present application;

FIG. 2 is a schematic diagram of an optical assembly provided by an embodiment of the present application;

FIG. 3 is a schematic diagram of an optical assembly provided by an embodiment of the present application;

FIG. 4 is a schematic diagram of an optical assembly provided by an embodiment of the present application;

FIG. 5 is a schematic diagram of an optical assembly provided by an embodiment of the present application;

FIG. 6 is a schematic diagram of an optical assembly provided by an embodiment of the present application;

FIG. 7 is an engineering schematic of an optical assembly according to an embodiment of the present application;

FIG. 8 is a schematic diagram of a light assembly provided by an embodiment of the present application;

FIG. 9 is an engineering schematic of an optical assembly according to an embodiment of the present application;

fig. 10 is a schematic diagram of a COMBO PON system according to an embodiment of the present application.

Detailed Description

The present application is described below based on examples, but the present application is not limited to only these examples. In the following detailed description of the present application, some specific details are set forth in detail. It will be apparent to one skilled in the art that the present application may be practiced without these specific details. Well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the present application.

Further, those of ordinary skill in the art will appreciate that the drawings provided herein are for illustrative purposes and are not necessarily drawn to scale.

Meanwhile, it should be understood that, in the following description, a "circuit" refers to a conductive loop constituted by at least one element or sub-circuit through electrical or electromagnetic connection. When an element or circuit is referred to as being "connected to" another element or element/circuit is referred to as being "connected between" two nodes, it may be directly coupled or connected to the other element or intervening elements may be present, and the connection between the elements may be physical, logical, or a combination thereof. In contrast, when an element is referred to as being "directly coupled" or "directly connected" to another element, it is intended that there are no intervening elements present.

Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is, what is meant is "including, but not limited to".

In the description of the present application, it is to be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. In addition, in the description of the present application, "a plurality" means two or more unless otherwise specified.

The optical component and the OLT provided by the embodiment of the application integrate the transmitting device and the receiving device applied to the GPON and the NG-PON together, simultaneously comprise two paths of transmitting signals with different wavelengths and two paths of receiving signals with different wavelengths, and are respectively used as the downlink signals and the uplink signals of the GPON and the NG-PON, so that the optical component and the OLT comprising the optical component can be compatible with the GPON and the NG-PON simultaneously, can be applied to the scene of the COMBO-PON and are convenient for upgrading and maintaining the network.

Fig. 1 is a light assembly provided in an embodiment of the present application, including: a transmitting unit 1, a wavelength division multiplexing device 2, a first receiver 3, a second receiver 4, a lens element 5 and an optical fiber interface 6. The wavelength division multiplexing device 2, the lens element 5, and the optical fiber interface 6 are sequentially disposed in the light exit direction of the emission unit 1. The emitting unit 1 is used for emitting light containing a first wavelength and a second wavelength; the lens element 5 is used for coupling light including the first wavelength and the second wavelength to the optical fiber interface 6 and for performing beam conversion on a received signal including the third wavelength and the fourth wavelength of the optical fiber interface 6.

The wavelength division multiplexing device 2 achieves full transmission with respect to the light of the first wavelength and the second wavelength, and achieves light splitting with respect to the light of the third wavelength and the fourth wavelength, and couples the light of the third wavelength and the light of the fourth wavelength to the first receiver 3 and the second receiver 4, respectively. The interference film type beam splitting device comprises a plurality of optical filters, and the inclination angles of the optical filters relative to the optical axis can be the same or different, so that total reflection or total transmission of light rays with different wavelengths can be realized respectively, and the beam splitting effect of the light is achieved.

When the optical component emits an optical signal, the emitting unit 1 emits light including a first wavelength and a second wavelength and is incident on the wavelength division multiplexing device 2, and the light passes through the wavelength division multiplexing device 2 to realize total transmission and is incident on the lens element 5. The lens element 5 is perpendicular to the optical axis of the optical assembly and centered on the optical axis, and its side facing the emission unit 1 is a convex lens surface capable of coupling light rays containing the first wavelength and the second wavelength to the optical fiber interface 6.

When the optical module receives an optical signal, the received signal at the optical fiber interface 6 includes a third wavelength and a fourth wavelength, and the optical beam is converted by the lens element 5 and enters the wavelength division multiplexing device 2. The wavelength division multiplexing device 2 separates the light of the third wavelength and the light of the fourth wavelength, and couples the separated light to corresponding different receivers (i.e., the first receiver 3 and the second receiver 4).

The optical component simultaneously comprises two paths of transmitting signals (a first wavelength and a second wavelength) with different wavelengths and two paths of receiving signals (a third wavelength and a fourth wavelength) with different wavelengths, so that the optical component can be respectively used as a downlink signal and an uplink signal of a GPON and an NG-PON and applied to a scene of a COMBO-PON. For example, the first wavelength is 1577nm as a downstream signal of NG-PON, the second wavelength is 1490nm as a downstream signal of GPON, the third wavelength is 1270nm as an upstream signal of NG-PON, and the fourth wavelength is 1310nm as an upstream signal of GPON.

Preferably, the wavelength division multiplexing device 2 is an interference thin film type beam splitting device, and includes a plurality of optical filters inside, and the inclination angles of the optical filters relative to the optical axis may be the same or different, so as to respectively realize total reflection or total transmission of light rays with different wavelengths, thereby achieving a light splitting effect.

In one embodiment, as shown in FIG. 2, the interference thin film type beam splitting device further includes a first filter 21 and a second filter 22.

When the optical module emits the optical signal, both the first filter 21 and the second filter 22 can achieve full transmission for the light including the first wavelength and the second wavelength from the emission unit 1.

When the optical component receives an optical signal, the first optical filter 21 realizes full transmission of light with the fourth wavelength and total reflection of light with the third wavelength for light with the third wavelength, so that the light with the third wavelength is coupled to the first receiver 3. The light of the fourth wavelength is totally reflected at the second filter 22 after the full transmission of the first filter 21, thereby coupling the light of the fourth wavelength to the second receiver 4.

In the same medium, the larger the wavelength of a light ray, the smaller the refractive index, and the larger the critical angle at which the light ray is totally reflected in the medium. Therefore, if the above-mentioned light splitting effect is achieved, the first filter 21 and the second filter 22 are both transflective filters, the reflective surfaces of the two filters face the lens element 5 and have the same dielectric constant, and the fourth wavelength is greater than the third wavelength, so that the light with smaller wavelength is totally reflected (the incident angle reaches the critical angle of the third wavelength, but does not reach the critical angle of the fourth wavelength) at the same incident angle at the first filter 21, and the light with larger wavelength is totally transmitted at the same time. After the first filter 21 achieves full transmission, the direction of the light of the fourth wavelength is not changed, and if total reflection is to be achieved in the second filter 22, the incident angle of the light at the second filter 22 should be increased properly, so the included angle between the second filter 22 and the optical axis needs to be smaller than that of the first filter 21 (i.e. the second filter 22 is inclined more toward the horizontal direction).

The interference film type beam splitting device in the embodiment has the advantages of uniform light splitting, compact structure, small volume and no occupation of large installation space.

In one embodiment, as shown in FIG. 3, the interference thin film type beam splitting device further includes a first filter 21, a second filter 22, and a third filter 23. The light incidence directions of the first receiver 3 and the second receiver 4 are perpendicular to the optical axis of the optical assembly, and the arrangement that the light incidence directions of the receivers are perpendicular to the optical axis enables the structure of the optical assembly to be more compact, and the miniaturization of the optical assembly is more favorably realized.

The principle of the arrangement of the first filter 21 and the second filter 22 is the same as that of the previous embodiment. When the light of the fourth wavelength having a larger incident angle is totally reflected by the second filter 22 and is aligned to be perpendicular to the optical axis (that is, the light incident direction of the corresponding second receiver 4 is perpendicular to the optical axis), the light of the third wavelength is difficult to be aligned to be perpendicular to the optical axis when the light of the third wavelength has the same incident angle after being totally reflected by the first filter 21, so that the third filter 23 needs to be further disposed to be fully reflected again by the third filter 23 and aligned to be perpendicular to the optical axis after being totally emitted, so that the light incident direction of the first receiver 3 can also be perpendicular to the optical axis, the optical assembly is more compact in structure, and miniaturization is facilitated.

In one embodiment, as shown in FIG. 4, the interference thin film type beam splitting device further includes a first filter 21, a second filter 22, a third filter 23, and a fourth filter.

When the optical assembly emits an optical signal, the first optical filter 21 is capable of achieving full transmission for light from the emission unit 1 including the first wavelength and the second wavelength.

When the optical module receives the optical signal, the first optical filter 21 realizes total reflection on the light with the third wavelength and the light with the fourth wavelength. The second filter 22 is aligned in the total reflection direction of the first filter 21, and has an inclination angle with respect to the optical axis such that the second filter can achieve total reflection of the light with the third wavelength and total reflection of the light with the third wavelength back to the first filter 21 and second total reflection at the first filter 21. At the same time, the second filter 22 fully transmits the light with the fourth wavelength, and couples the light with the fourth wavelength to the second receiver 4. The third filter 23 is aligned in the second total reflection direction of the first filter 21, and has an inclination angle with respect to the optical axis such that it can realize total reflection of the light of the third wavelength. The fourth filter 24 is aligned in the total reflection direction of the third filter 23, and is configured to fully transmit the light of the third wavelength and couple the light of the third wavelength to the first receiver 3.

In this embodiment, by improving the placement of the optical filters, the distance between the first optical filter 21 and the lens element 5 is shortened, the length of the interference thin film type beam splitter in the optical axis direction is shortened, and the overall structural length of the optical assembly is further reduced.

In one embodiment, as shown in FIG. 5, the interference thin film type beam splitting device further includes a first filter 21, a second filter 22, a third filter 23, and a fourth filter.

When the optical assembly emits an optical signal, the first filter 21 is capable of achieving full transmission for light from the emission unit 1 including the first wavelength and the second wavelength.

When the optical module receives the optical signal, the first optical filter 21 realizes total reflection on the light with the third wavelength and the light with the fourth wavelength. The second filter 22 is aligned in the total reflection direction of the first filter 21, and is inclined at an angle relative to the optical axis such that it can achieve total reflection of the light beams of the third and fourth wavelengths. The third filter 23 is aligned in the total reflection direction of the second filter 22, and has an inclination angle with respect to the optical axis, which can achieve total reflection for the third wavelength and total transmission for the fourth wavelength, and couple the light of the fourth wavelength to the second receiver 4. The fourth filter 24 is aligned in the total reflection direction of the third filter 23, and is configured to fully transmit the light of the third wavelength and couple the light of the third wavelength to the first receiver 3.

In this embodiment, by improving the placement of the optical filter, the distance between the first optical filter 21 and the lens element 5 is shortened, the length of the interference thin film type beam splitter in the optical axis direction is shortened, and the overall structure length of the optical assembly is further reduced.

In one embodiment, as shown in fig. 6, the emission unit 1 further includes a first laser 11, a second laser 12, a fifth filter 13, and an isolator 14. Wherein the first laser 11 is adapted to emit light of a first wavelength and the second laser 12 is adapted to emit light of a second wavelength. The first laser 11 and the second laser 12 have different light emission directions. The direction of the light with the first wavelength is parallel to the optical axis of the optical assembly, the fifth optical filter 13 realizes full transmission to the light with the first wavelength, the light with the second wavelength enters the fifth optical filter 13 at a certain angle and is totally reflected at the fifth optical filter 13, and the direction after total reflection is the same as that of the light with the first wavelength, so that the light with the first wavelength and the light with the second wavelength are calibrated to the same direction by using the fifth optical filter 13 and are output from the emission unit 1 after passing through the isolator 14.

Preferably, the light emitting direction of the second laser 12 is perpendicular to the optical axis of the optical assembly, the included angle between the fifth filter 13 and the optical axis is 45 °, so that the direction of the light with the second wavelength after being totally reflected by the fifth filter 13 is the same as the direction of the light with the first wavelength after being totally transmitted.

In this embodiment, the packages of the first laser 11 and the second laser 12 in the transmitting unit 1 are all coaxial window (TO-CAN) packages. The first receiver 3 and the second receiver 4 in the optical assembly both employ TO-CAN packages. The engineering schematic diagram of the optical assembly of the present embodiment after packaging is shown in fig. 7.

In one embodiment, as shown in fig. 8, the transmitting unit 1 further includes a first light emitting chip 15, a second light emitting chip 16, a first lens 17, a second lens 18, a total reflection prism set 19, and an isolator 14. Wherein the outgoing light of the first light emitting chip 15 has a first wavelength and the outgoing light of the second light emitting chip 16 has a second wavelength.

The first lens 17 is disposed in the light exiting direction of the first light emitting chip 15, and the second lens 18 is disposed in the light exiting direction of the second light emitting chip 16, and is respectively configured to convert the exiting light of the first light emitting chip 15 and the second light emitting chip 16 into light and respectively enter the total reflection prism group 19. The total reflection prism group 19 is composed of a plurality of isosceles triangle prisms, couples the light of the first wavelength and the light of the second wavelength into a bundle of light, and outputs the bundle of light from the emission unit 1 after being isolated by the isolator 14.

The transmission unit 1 in this embodiment employs a BOX type (BOX) package, and the first receiver 3 and the second receiver 4 of the optical component each employ a TO-CAN package. The transmission unit 1 is packaged by the BOX, so that heat dissipation is facilitated, and power consumption of a semiconductor cooler required by a light transmission chip is reduced. The engineering schematic diagram of the optical assembly of the present embodiment after packaging is shown in fig. 9.

In the above embodiments, the first Laser 11 is an Electro-absorption Modulated Laser (EML), and the second Laser 12 is a distributed Feedback Laser (DFB). The first light emitting chip 15 is an EML chip and the second light emitting chip 16 is a DFB chip. The first receiver 3 and the second receiver 4 are Avalanche Photodiode (APD) based optical receivers. The optical fiber interface 6 is a single-fiber bidirectional interface, and double transmission and double reception of a single fiber are realized by using a wavelength division multiplexing technology based on the PLC, that is, two paths of light emitting signals with different wavelengths and two paths of light receiving signals with different wavelengths can exist in one optical fiber at the same time, thereby being beneficial to saving optical fiber resources.

The optical module provided by the above embodiment can be integrated into an optical module conforming to SFP (Small Form-factor plug connectors) standard or SFP + standard and applied in the OLT. The OLT may be applied to a COMBO PON scenario, and as shown in fig. 10, the OLT is connected to an Optical Distribution Network (ODN), and the ODN allocates a GPON signal to a plurality of ONUs of a corresponding GPON and an NG-PON signal to a plurality of ONUs of a corresponding NG-PON. One path of optical transmitting signal and one path of optical receiving signal respectively bear downlink and uplink signals of GPON, and the other path of optical transmitting signal and the other path of optical receiving signal respectively bear downlink and uplink signals of NG-PON. Therefore, the OLT is compatible with the GPON and the NG-PON at the same time, smooth upgrade from the GPON system to the NG-PON system is facilitated, the number of the OLTs in an optical network is reduced, and the flexibility of system deployment is improved.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A light assembly, comprising: the device comprises a transmitting unit, a wavelength division multiplexing device, a first receiver, a second receiver, a lens element and an optical fiber interface;

the wavelength division multiplexing device, the lens element and the optical fiber interface are sequentially arranged in the light emergent direction of the emission unit; the emitting unit is used for emitting light rays containing a first wavelength and a second wavelength; the lens element is used for coupling light rays containing the first wavelength and the second wavelength to the optical fiber interface and carrying out beam conversion on uplink signals of the third wavelength and the fourth wavelength;

2. The optical assembly of claim 1, the wavelength division multiplexing device being an interferometric thin film type beam splitting device comprising a plurality of optical filters.

3. The optical module of claim 2, wherein the interference thin film type beam splitting device includes a first filter and a second filter;

the first optical filter realizes total reflection on the light with the third wavelength, couples the light with the third wavelength to the first receiver, realizes total transmission on the light with the fourth wavelength, and transmits the light with the fourth wavelength to the second optical filter; the second optical filter realizes total reflection on the light with the fourth wavelength and couples the light with the fourth wavelength to the second receiver.

4. The optical subassembly of claim 3, wherein the first receiver has a light incident direction perpendicular to the optical axis of the optical subassembly, and the interference thin film type beam splitting device further comprises a third filter;

the third optical filter totally reflects the light of the third wavelength totally reflected by the first optical filter again, so as to be coupled to the first receiver.

5. The optical assembly of claim 2, wherein the interference thin film type beam splitting device comprises a first filter, a second filter, a third filter, and a fourth filter;

the first optical filter realizes total reflection on the light rays with the third wavelength and the fourth wavelength; the second optical filter is calibrated in the total reflection direction of the first optical filter, the inclination angle of the second optical filter relative to the optical axis can enable the second optical filter to realize total reflection on the light with the third wavelength and to enable the light with the third wavelength to be totally reflected back to the first optical filter and to realize second total reflection on the first optical filter, the second optical filter realizes total transmission on the light with the fourth wavelength and couples the light with the fourth wavelength to the second receiver; the third optical filter is calibrated in the second total reflection direction of the first optical filter, and the inclination angle of the third optical filter relative to the optical axis can enable the third optical filter to realize total reflection on the light with the third wavelength; the fourth optical filter is calibrated in the total reflection direction of the third optical filter, realizes total transmission on the light with the third wavelength, and couples the light with the third wavelength to the first receiver.

6. The optical module of claim 2, wherein the interference thin film type beam splitting device includes a first filter, a second filter, a third filter, and a fourth filter;

the first optical filter realizes total reflection on the light rays with the third wavelength and the fourth wavelength; the second optical filter is calibrated in the total reflection direction of the first optical filter, and the inclination angle of the second optical filter relative to the optical axis can enable the second optical filter to realize total reflection on the light rays with the third wavelength and the fourth wavelength; the third optical filter is calibrated in the total reflection direction of the second optical filter, the inclination angle of the third optical filter relative to the optical axis can realize total reflection on the third wavelength and total transmission on the fourth wavelength, and the light ray of the fourth wavelength is coupled to the second receiver; the fourth optical filter is calibrated in the total reflection direction of the third optical filter, realizes total transmission on the light with the third wavelength, and couples the light with the third wavelength to the first receiver.

7. The light assembly of claim 1, wherein the emitting unit comprises: the optical filter comprises a first laser, a second laser, a fifth optical filter and an isolator;

the first laser is used for emitting light rays with a first wavelength, and the second laser is used for emitting light rays with a second wavelength; the fifth optical filter realizes full transmission on the light with the first wavelength and total reflection on the light with the second wavelength, couples the light with the first wavelength and the light with the second wavelength to the same direction, and outputs the light from the emission unit after being isolated by the isolator.

8. The optical assembly of claim 7, wherein the first laser, the second laser, the first receiver, and the second receiver are packaged in a TO-CAN package.

9. The optical assembly of claim 7, wherein the light emitting direction of the second laser is perpendicular to the optical axis of the optical assembly, and the angle between the fifth filter and the optical axis is 45 °.

10. The light assembly of claim 1, wherein the emitting unit comprises: the device comprises a first light emitting chip, a second light emitting chip, a first lens, a second lens, a total reflection prism group and an isolator;

the first lens and the second lens are respectively arranged in the light outgoing direction of the first light emitting chip and the second light emitting chip and are used for converting the outgoing light of the first light emitting chip and the second light emitting chip into collimated light respectively and enabling the collimated light to be incident into the total reflection prism group respectively so as to be coupled into a bundle of collimated light, and the collimated light is isolated by the isolator and then output from the emitting unit.

11. The optical assembly of claim 10, wherein the package of the transmitting unit is a BOX package and the packages of the first and second receivers are TO-CAN packages.

12. The optical subassembly of claim 1, wherein the first wavelength of light is a downstream signal of an NG-PON, the second wavelength of light is a downstream signal of a GPON, the third wavelength of light is an upstream signal of an NG-PON, and the fourth wavelength of light is an upstream signal of a GPON.

13. The optical assembly of claim 1, wherein the fiber optic interface is a single fiber bi-directional interface.

14. An Optical Line Terminal (OLT) comprising an optical assembly according to any one of claims 1 to 13.