Multiplexer

Abstract

The present invention discloses a multiplexer that integrates the multi-channel transmission functions of a wavelength division multiplexer into a single device, significantly reducing the size of the wavelength division module. The multiplexer comprises an outer sleeve, a first inner sleeve, and a second inner sleeve; one end of the first inner sleeve is provided with a first multi-fiber optical head, and the other end of the first inner sleeve is provided with a first multi-focus lens; one end of the second inner sleeve is provided with a second multi-focus lens; the other end of the second inner sleeve is provided with a second multi-fiber optical head; and a filter set is provided between the first and second multi-focus lenses. Using this multiplexer can reduce the size of the multiplexer, increase reflection isolation capability, reduce signal interference between adjacent channels, increase the signal-to-noise ratio, and improve channel communication quality.

Description

Technical Field

[0001] The present invention relates to an optical module of signal wavelength transmission multiplexing technology in the field of optical fiber communication, and in particular to a multi-channel optical multiplexer. Background Art

[0002] It's no secret that with the development of new services like autonomous driving, cloud services, and the Internet of Things, the 5G era of high-speed, high-capacity data transmission has arrived. To accommodate these upgrades, particularly in metropolitan area networks and access networks, 5G fronthaul networks will need to transmit multiple signals on a single optical fiber. This necessitates the use of wavelength division multiplexers (WDMs) and demultiplexers (DDMs). These facilitate compact upgrades or retrofits, saving fiber usage and laying costs. Market demand for WDM / DDM modules is expected to continue to grow.

[0003] Currently, most existing WDM modules use a cascaded single-device approach to fiber optics, with the single-device structure primarily consisting of a filter. A single WDM device consists of an outer sleeve, a dual-fiber fiber head, a primary lens, a filter, and a single-fiber collimator.

[0004] The transmission wavelength λ1 is input from the first optical fiber of the dual-fiber optical fiber head, collimated by the first lens, passed through the filter, and then converged into the optical fiber of the single-fiber collimator through the lens of the single-fiber collimator for transmission, becoming the first signal channel.

[0005] The function of the filter is to allow wavelength λ1 to pass, while blocking other wavelengths λ2 / λ3... That is, the other wavelengths are reflected back by the filter, then converged by the lens into the optical fiber of the dual-fiber optical head for transmission, becoming the 2nd, 3rd,..., Nth signal channel.

[0006] However, in reality, the signal λ1 cannot completely penetrate the filter. A portion of the light of λ1 will be reflected back from the surface of the filter and then converged into the second optical fiber of the dual-fiber optical head through the first lens. That is, the signal of the first channel crosstalks to the 2nd, 3rd, ..., Nth channel, and the signal of the second channel crosstalks to the 3rd, 4th, ..., Nth channel. Figure 1 This crosstalk is referred to as adjacent isolation and non-adjacent isolation in the module test parameters. The more severe the interference, the lower the adjacent isolation and non-adjacent isolation test values will be, failing to meet high index requirements, resulting in a poor channel communication environment, a high signal-to-noise ratio, and reduced communication quality.

[0007] Meanwhile, in the process of forming a wavelength division multiplexer / demultiplexer by cascading different single devices according to module performance requirements in existing wavelength division modules, the resulting wavelength division multiplexer is large in size and inconvenient to install and arrange. Summary of the Invention

[0008] The technical problem to be solved by this invention is to provide a multiplexer that integrates the multi-channel transmission functions of a wavelength division multiplexer into a single device, significantly reducing the size of the wavelength division module. Furthermore, this invention can increase reflection isolation, reduce signal interference between adjacent channels, increase the signal-to-noise ratio, and improve channel communication quality.

[0009] The technical solution adopted by the present invention to solve the technical problem is: a multiplexer comprises an outer sleeve, a first inner sleeve and a second inner sleeve;

[0010] The first inner sleeve is arranged at one end of the outer sleeve; the second inner sleeve is arranged at the other end of the outer sleeve;

[0011] A first multi-fiber optical fiber head is provided at one end of the first inner sleeve, and a first multi-focal lens is provided at the other end of the first inner sleeve;

[0012] The first multi-fiber optical fiber head has multiple groups of optical fibers, and each group of optical fibers includes a first optical fiber and a second optical fiber; a second filter is provided at one end of the second optical fiber; and the filtering wavelengths of all the second filters are different;

[0013] Between two adjacent groups of optical fibers, one end of the second optical fiber in the upper group of optical fibers is connected to one end of the first optical fiber in the lower group of optical fibers;

[0014] The focal points on the first multi-focal lens correspond one-to-one to the multiple groups of optical fibers in the first multi-fiber optical fiber head, that is, one group of optical fibers corresponds to one focal point;

[0015] A second multi-focal lens is provided at one end of the second inner sleeve; a second multi-fiber optical fiber head is provided at the other end of the second inner sleeve; and a plurality of third optical fibers are provided in the second multi-fiber optical fiber head;

[0016] The focal points in the second multifocal lens correspond one-to-one to the third optical fibers, that is, one third optical fiber corresponds to one focal point;

[0017] A filter set is provided between the first multifocal lens and the second multifocal lens; the filter set includes a plurality of first filters having different filtering wavelengths; and each first filter is provided between a focus on the first multifocal lens and a focus on the second multifocal lens;

[0018] The first filter and the second filter correspond one to one; the first filter can only pass light waves with a wavelength of λ, and the second filter filters out light waves with a wavelength of λ.

[0019] Preferably, the outer sleeve, the first inner sleeve and the second inner sleeve are all made of glass tubes.

[0020] Preferably, the first multi-fiber optical fiber head and the first multi-focal lens are bonded to the first inner sleeve by glue; the second multi-focal lens and the second multi-fiber optical fiber head are bonded to the second sleeve by glue.

[0021] Preferably, both ends of the outer sleeve are sealed by glue.

[0022] Preferably, the second filter is adhered to the end face of the second optical fiber by glue.

[0023] Preferably, a second filter is formed on the end face of the second optical fiber by coating.

[0024] Preferably, the position on the first lens where the first filter is attached is coated to form a plurality of filtering surfaces on the lens having the same function as the first filter.

[0025] The beneficial effect of the present invention is that the multiplexer of the present invention integrates the multi-channel transmission function of the wavelength division multiplexer into an integral device, thereby greatly reducing the size of the wavelength division module.

[0026] Secondly, the dual-fiber fiber head is changed to a multi-fiber fiber head, and the single-focus lens is changed to a multi-focus lens; the multi-focus lens is selected reasonably to control the distance between the lens focal points; according to the distance between the lens focal points, the core distance of the multi-fiber fiber head is controlled, and a small filter is added to the fiber core position of the reflective light path of the fiber head to increase the reflection isolation capability; reduce the signal interference of adjacent channels, increase the signal-to-noise ratio, and improve the channel communication quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the optical path of the device cascade of the wavelength division module in the prior art;

[0028] Figure 2 is a schematic diagram of light waves having wavelengths λ1 / λ2 / λ3 / λ4 / ... passing through an optical multiplexer in an embodiment of the present invention;

[0029] Figure 3 is a schematic structural diagram of a multiplexer in an embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram of the optical path principle of the multiplexing function of the multiplexer in an embodiment of the present invention;

[0031] Markings in the figure: 10 - outer sleeve, 20 - first inner sleeve, 30 - second inner sleeve, 2 - first multi-fiber optical fiber head, 3 - first multi-focal lens, 4 - second multi-focal lens, 5 - second multi-fiber optical fiber head, 6 - first filter, 7 - second filter. DETAILED DESCRIPTION

[0032] The present invention will be further described below with reference to the accompanying drawings and examples.

[0033] like Figures 2 to 4 As shown, the multiplexer of the present invention comprises an outer sleeve 10, a first inner sleeve 20 and a second inner sleeve 30;

[0034] The first inner sleeve 20 is disposed at one end of the outer sleeve 10; the second inner sleeve 30 is disposed at the other end of the outer sleeve 10;

[0035] A first multi-fiber optical fiber head 2 is provided at one end of the first inner sleeve 20, and a first multi-focal lens 3 is provided at the other end of the first inner sleeve 20;

[0036] The first multi-fiber optical fiber head 2 has multiple groups of optical fibers, and each group of optical fibers includes a first optical fiber 21 and a second optical fiber 22; a second filter 7 is provided at one end of the second optical fiber 22; and the filtering wavelengths of all the second filters 7 are different;

[0037] Between two adjacent groups of optical fibers, one end of the second optical fiber 22 in the upper group of optical fibers is connected to one end of the first optical fiber 21 in the lower group of optical fibers;

[0038] The focal points on the first multi-focal lens 3 correspond one-to-one to the multiple groups of optical fibers in the first multi-fiber optical fiber head 2, that is, one group of optical fibers corresponds to one focal point;

[0039] A second multi-focal lens 4 is provided at one end of the second inner sleeve 30; a second multi-fiber optical fiber head 5 is provided at the other end of the second inner sleeve 30; and a plurality of third optical fibers 51 are provided in the second multi-fiber optical fiber head 5;

[0040] The focal points on the second multi-focal lens 4 correspond one-to-one to the third optical fibers 51 in the second multi-fiber optical fiber head 5, that is, one third optical fiber 51 corresponds to one focal point;

[0041] A filter set is provided between the first multifocal lens 3 and the second multifocal lens 4; the filter set includes a plurality of first filters 6 with different filtering wavelengths; and each first filter 6 is provided between a focus on the first multifocal lens 3 and a focus on the second multifocal lens 4;

[0042] The first filter 6 corresponds to the second filter 7 one-to-one; the first filter 6 can only pass light waves with a wavelength of λ and reflect light waves of remaining wavelengths, and the second filter 7 filters out light waves with a wavelength of λ.

[0043] In the application process, the multiplexer is first prepared:

[0044] like Figure 3 As shown:

[0045] 1. Attach the filter assembly to the multi-fiber optical head 2 with glue, so that the second filter 7 is glued to the second optical fiber 22 (reflection path optical fiber) of the multi-fiber optical head 2; or form the second filter 7 by coating the end face of the second optical fiber 22; this part is called component 1;

[0046] 2. Attach the first filter 6 to the right-angled surface of the first multifocal lens 3. According to lens principles, the filter must be attached at a position that transmits and passes parallel light from the corresponding focal point. This position is marked with a groove on the right-angled surface of the first lens 3 to facilitate the attachment of the filter. This part is called component 2.

[0047] 3. Optically couple the second multifocal lens 4 to the second multifiber optical head 5, ensuring that the core of the Nth optical fiber of the second multifiber optical head 5 corresponds to the Nth focal point of the second multifocal lens 4. Then, insert the second inner sleeve 30 and seal it with glue. This part is called Component 3.

[0048] 4. Couple the above components 1 and 2 through the reflective optical path until the insertion loss is minimized, insert them into the first inner sleeve 20, and seal them with glue. After completion, this part is called a reflective semi-finished product.

[0049] 5. The semi-finished reflective component is coupled to the third component through the transmission optical path until the insertion loss is minimized. The component is then inserted into the outer sleeve 10 and sealed with glue on both sides. This completes the product commissioning. After baking and testing, the product is complete.

[0050] Working principle:

[0051] The cores of the first group of optical fibers 21 and 22 in the first multi-fiber optical fiber head 2 need to correspond to the first focus of the first multifocal lens 3, that is, be located at the first focus of the first multifocal lens 3; similarly, the cores of the second group of optical fibers in the first multi-fiber optical fiber head 2 are at the second focus of the first multifocal lens 3, and so on. The Nth group of optical fibers in the multi-fiber optical fiber head 2 is at the Nth focus of the first multifocal lens 3.

[0052] When light of all wavelengths λ1 / λ2 / λ3 / λ4 / λ5 / λ6..... is input from the first optical fiber 21 of the first multi-fiber optical head 2 and passes through the focus of the first multifocal lens 3, it is collimated by the first multifocal lens 3 to form parallel light and output to the first filter 6. Because the first filter 6 can only transmit light of λ1 and reflect light of the remaining wavelengths, the light of λ1 can enter the second multifocal lens 4 in parallel for transmission, and after being converged by the second multifocal lens 4, it is transmitted into the third light 51 in the second multi-fiber optical head 5. The core of the uppermost third light 51 is at the first focus of the second multifocal lens 4, and the core of the next third light 51 is at the second focus of the second multifocal lens 4. Similarly, the core of the Nth optical fiber of the second multifocal lens 4 must be at the Nth focus of the second multifocal lens 4.

[0053] The light of wavelengths λ2 / λ3 / λ4 / λ5 / λ6, etc., reflected by the first filter 6, is focused by the first multifocal lens 3 and enters the core of the second optical fiber 22 of the first optical group. Since the second optical fiber 22 of the first optical group is externally connected to the first optical fiber 21 of the second optical group, these wavelengths of light are transmitted by the first optical fiber 21 of the second optical group to the second focal point of the first multifocal lens 3. After being collimated by the first multifocal lens 3, they are then incident on the second first filter 6 in parallel. Because the second first filter 6 only transmits wavelength λ2 and reflects the remaining wavelengths, the wavelength λ2 is incident on the second multifocal lens 4 in parallel. After being focused by the second multifocal lens 4, it is transmitted to the second third optical fiber 51 of the second multifiber optical head 5. The remaining wavelengths λ3 / λ4 / λ5 / λ6, etc., reflected by the second first filter 6, are then focused by the first multifocal lens 3 and transmitted into the second optical fiber 22 of the second optical group. The transmission principles for the remaining channels are the same as described above.

[0054] The present invention adds a second filter 7 to the second optical fiber 22 of the first optical fiber group to reflect the portion of light λ1 reflected by the first filter 6 and transmit light of other wavelengths, thereby reducing signal crosstalk, increasing the signal-to-noise ratio, and improving channel quality. Second filters 7 with different filtering wavelengths are also provided at one end of the second optical fiber 22 of other groups.

[0055] In summary, the function of the optical multiplexer described in the present invention is to multiplex several wavelength signals λ1 / λ2 / λ3 / λ4 / λ5 / λ6... transmitted by several optical fibers into a single optical fiber COM end for transmission, thereby reducing the number of optical fibers used. Alternatively, it can separate several signals λ1 / λ2 / λ3 / λ4 / λ5 / λ6... transmitted by a single optical fiber and transmit them to the demultiplexing function on the corresponding channels.

[0056] The multiplexer of the present invention integrates the multi-channel transmission function of the wavelength division multiplexer into one device, thereby greatly reducing the size of the wavelength division module.

[0057] Secondly, the dual-fiber collimator is changed to a multi-fiber collimator, and the single-focus lens is changed to a multi-focus lens; the multi-focus lens is reasonably selected to control the distance between the lens focal points; according to the distance between the lens focal points, the core distance of the multi-fiber optical fiber head is controlled, and a small filter is added to the optical fiber core position of the reflective light path of the optical fiber head to increase the reflection isolation capability; reduce the signal interference of adjacent channels, increase the signal-to-noise ratio, and improve the channel communication quality.

[0058] In order to reduce costs, preferably, the outer sleeve 10, the first inner sleeve 20 and the second inner sleeve 30 are all made of glass tubes.

[0059] To facilitate installation, specifically, the first multi-fiber optical head 2 and the first multi-focal lens 3 are glued into the first inner sleeve 20; the second multi-focal lens 4 and the second multi-fiber optical head 5 are glued into the second sleeve 30.

[0060] In order to prevent moisture and dust from affecting the equipment, both ends of the outer sleeve 10 are further sealed by glue.

[0061] For ease of installation, preferably, the second filter 7 is glued to the end face of the second optical fiber 22. Another preferred embodiment is that the second filter 7 is formed on the end face of the second optical fiber 22 by coating.

[0062] The first filter 6 is glued to the vertical surface of the first multifocal lens 3. Alternatively, a plurality of filter surfaces having the same function as the second filter 6 can be formed on the lens 3 by coating the position where the first filter 6 is attached.

Claims

1. A multiplexer, characterized in that: It comprises an outer sleeve (10), a first inner sleeve (20) and a second inner sleeve (30); The first inner sleeve (20) is arranged at one end of the outer sleeve (10); the second inner sleeve (30) is arranged at the other end of the outer sleeve (10); A first multi-fiber optical fiber head (2) is provided at one end of the first inner sleeve (20), and a first multi-focal lens (3) is provided at the other end of the first inner sleeve (20); The first multi-fiber optical fiber head (2) has multiple groups of optical fibers, and each group of optical fibers includes a first optical fiber (21) and a second optical fiber (22); a second filter (7) is provided at one end of the second optical fiber (22); and the filtering wavelengths of all the second filters (7) are different; Between two adjacent groups of optical fibers, one end of the second optical fiber (22) in the upper group of optical fibers is connected to one end of the first optical fiber (21) in the lower group of optical fibers; The focal points on the first multi-focal lens (3) correspond one-to-one to the multiple groups of optical fibers in the first multi-fiber optical fiber head (2), that is, one group of optical fibers corresponds to one focal point; A second multi-focal lens (4) is provided at one end of the second inner sleeve (30); a second multi-fiber optical fiber head (5) is provided at the other end of the second inner sleeve (30); and a plurality of third optical fibers (51) are provided in the second multi-fiber optical fiber head (5); The focal points on the second multi-focal lens (4) correspond one-to-one to the third optical fibers (51) in the second multi-fiber optical fiber head (5), that is, one third optical fiber (51) corresponds to one focal point; A filter set is provided between the first multifocal lens (3) and the second multifocal lens (4); the filter set comprises a plurality of first filters (6) having different transmission and passing wavelengths; and each first filter (6) is provided between a focus on the first multifocal lens (3) and a focus on the second multifocal lens (4); The first filter (6) and the second filter (7) correspond one to one; the first filter (6) can only pass light waves with a wavelength of λ, and the second filter (7) filters out light waves with a wavelength of λ.

2. The optical multiplexer according to claim 1, wherein: The outer sleeve (10), the first inner sleeve (20) and the second inner sleeve (30) are all made of glass tubes.

3. The optical multiplexer according to claim 2, wherein: The first multi-fiber optical fiber head (2) and the first multi-focal lens (3) are bonded to the first inner sleeve (20) by glue; and the second multi-focal lens (4) and the second multi-fiber optical fiber head (5) are bonded to the second inner sleeve (30) by glue.

4. The optical multiplexer according to claim 3, wherein: Both ends of the outer sleeve (10) are sealed by glue.

5. The optical multiplexer according to claim 4, wherein: The second filter (7) is glued to the end face of the second optical fiber (22).

6. The optical multiplexer according to claim 4, wherein: A second filter (7) is formed on the end face of the second optical fiber (22) by coating.

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