Dense wavelength division multiplexing devices

Abstract

This utility model belongs to the field of optical communication technology, and particularly relates to a dense wavelength division multiplexing (DWDM) device. A DWDM device includes: a base plate; a common-end fiber collimator disposed on the base plate; a channel-end fiber collimator assembly disposed on the base plate; and an optical assembly disposed on the base plate and forming a free-space optical path. The optical assembly is configured to split multi-wavelength optical signals incident from the common-end fiber collimator via the free-space optical path, and couple them respectively to corresponding fiber collimators in the channel-end fiber collimator assembly. The optical assembly includes a DWDM filter assembly; the filter assembly includes at least one channel pre-separation filter, configured to receive optical signals at an actual incident angle greater than the nominal application angle of the channel pre-separation filter, so that the target wavelength filtered by the channel pre-separation filter is different from its nominal wavelength at the nominal application angle.

Description

Technical Field

[0001] This invention belongs to the field of optical communication technology, and particularly relates to a dense wavelength division multiplexing device. Background Technology

[0002] With the full commercialization of 5G communication technology and the rapid development of cloud computing and big data centers, global data traffic is experiencing explosive growth. Traditional electrical communication technologies and network transmission capacities are struggling to meet the ever-increasing bandwidth demands. Fiber optic communication, especially dense wavelength division multiplexing (DWDM) technology, has become a core technology for carrying massive data transmissions and addressing bandwidth challenges due to its significant advantages of high transmission rates, large capacity, and low loss. By transmitting multiple optical signals of different wavelengths simultaneously within a single optical fiber, DWDM technology can increase transmission capacity by tens or even hundreds of times without increasing the physical deployment cost of optical fibers. Therefore, it has been widely used in long-distance, high-capacity communication scenarios such as backbone networks, metropolitan area networks, and data center interconnections.

[0003] In implementing multiplexing and demultiplexing functions in DWDM systems, there are currently two main technical solutions in the industry: those based on thin-film filtering (TFF) technology and those based on arrayed waveguide grating (AWG) technology. Devices based on TFF technology utilize the interference principle of multilayer dielectric films to filter specific wavelengths, offering advantages such as excellent single-channel performance, low insertion loss, high isolation, and mature technology. However, when traditional TFF solutions are applied to multi-channel (typically 16 channels or more) DWDM systems, multiple independent filtering devices must be cascaded. This cascaded architecture causes the overall device size to increase dramatically with the number of channels. Simultaneously, losses accumulate with each stage of optical signal transmission, leading to a significant increase in cost and packaging complexity. This severely limits the competitiveness of TFF technology in high-channel-count applications.

[0004] Unlike TFF technology, AWG devices based on planar optical waveguide (PLC) technology are easy to integrate, have strong scalability in channel count, and their cost does not increase linearly with the number of channels. This is especially true in high-channel-count applications (40 channels or more), where their economic and compact advantages are significant. However, AWG devices also have inherent drawbacks, such as sensitivity to operating temperature, relatively complex manufacturing processes, and inferior performance compared to TFF devices in certain aspects. Therefore, in the current technology landscape, TFF solutions dominate the low-channel-count market, while AWG solutions occupy the high-channel-count market. This results in a lack of an ideal solution for applications requiring a moderate number of channels (e.g., 16 to 20 channels) and demanding high standards in terms of device size, cost, and overall performance. Therefore, a pressing technical challenge is to overcome the inherent drawbacks of traditional TFF technology in multi-channel applications—its large size and high cost due to cascaded architecture—and develop a dense wavelength division multiplexing (WDM) device that combines the excellent optical performance of TFF technology with high integration and low cost. Utility Model Content

[0005] The purpose of this invention is to address the above-mentioned shortcomings and provide a dense wavelength division multiplexing device.

[0006] A dense wavelength division multiplexing device includes:

[0007] Base plate;

[0008] A common-end fiber optic collimator is mounted on the base plate;

[0009] The channel-end fiber optic collimator assembly is disposed on the base plate; and

[0010] An optical component is disposed on the base plate and forms a free space optical path. The optical component is configured to split a multi-wavelength optical signal incident from the common end fiber collimator via the free space optical path and couple it to the corresponding fiber collimator in the channel end fiber collimator assembly.

[0011] The optical component includes a dense wavelength division multiplexing (DWDM) filter assembly; the filter assembly includes at least one channel pre-separation filter configured to receive an optical signal at an actual incident angle greater than the nominal application angle of the channel pre-separation filter, such that the target wavelength filtered out by the channel pre-separation filter is different from its nominal wavelength at the nominal application angle.

[0012] Furthermore, the channel pre-separation filter is disposed on the base plate and located in the direct output optical path of the common end fiber collimator, for filtering out the first channel optical signal group from the incident multi-wavelength optical signal.

[0013] Furthermore, the optical component also includes a jumper, which is disposed on the base plate and located in the optical path after the channel pre-separation filter, for dividing the incident multi-wavelength optical signal into a first transmitted optical path and a second reflected optical path.

[0014] Furthermore, the optical component also includes a first reflector and a second reflector; the first reflector is disposed adjacent to the transmission outlet of the jumper and is used to perform a first reflection on the first optical path; the second reflector is disposed in the first optical path after the first reflection and is used to perform a second reflection to change the propagation direction of the first optical path.

[0015] Furthermore, the filter assembly further includes a first filter group, a second filter group, a third filter group, and a fourth filter group; the first optical path is guided by the second reflector to pass sequentially through the first filter group and the second filter group, the first optical path filters out a second channel optical signal group through the first filter group, and the first optical path filters out a third channel optical signal group through the second filter group; the second optical path is directly guided to pass sequentially through the third filter group and the fourth filter group, the second optical path filters out a fourth channel optical signal group through the third filter group, and the second optical path filters out a fifth channel optical signal group through the fourth filter group.

[0016] Furthermore, the optical component also includes a prism fixed to one side of the base plate, the prism being configured to intercept and reflect the first channel optical signal group, the third channel optical signal group, and the fifth channel optical signal group to the back side of the base plate.

[0017] Furthermore, the channel-end fiber collimator assembly includes a first channel-end fiber collimator group, a second channel-end fiber collimator group, a third channel-end fiber collimator group, a fourth channel-end fiber collimator group, and a fifth channel-end fiber collimator.

[0018] The first channel-end fiber collimator group and the second channel-end fiber collimator group are disposed on the front side of the base plate. The first channel-end fiber collimator group receives the second channel optical signal group, and the second channel-end fiber collimator group receives the fourth channel optical signal group.

[0019] The third-channel fiber collimator group, the fourth-channel fiber collimator group, and the fifth-channel fiber collimator are all disposed on the back of the base plate. The third-channel fiber collimator group receives the third-channel optical signal group, the fourth-channel fiber collimator group receives the fifth-channel optical signal group, and the fifth-channel fiber collimator receives the first-channel optical signal group.

[0020] Furthermore, the base plate is made of ceramic material or alloy material with a low coefficient of thermal expansion, and its surface is provided with stepped structures or engravings for bearing and precise positioning.

[0021] Furthermore, the prism is a roof-shaped prism with an isosceles trapezoidal cross-section.

[0022] Furthermore, the nominal application angle is 1.8 degrees, and the actual incident angle is greater than 5 degrees.

[0023] The beneficial effects of this utility model are:

[0024] This invention provides a dense wavelength division multiplexing (DWDM) device. By constructing an integrated free-space optical path system on a single substrate, it completely eliminates the device cascading method required by traditional TFF solutions, thus fundamentally solving the technical problems of large device size, loose structure, and increased cost caused by cascading. This achieves high integration and miniaturization of the device. This invention uses conventional DWDM filters with an actual incident angle greater than its nominal application angle. Utilizing the physical relationship between the incident angle and the center wavelength offset, it enables precise filtering of the target wavelength channel using low-cost standard filters, thereby avoiding the need for customized, expensive large-angle dedicated filters. The structural design of this invention reduces the material cost of core components. While maintaining the inherent excellent optical performance of TFF technology, it provides a compact, reliable, and cost-effective new multi-channel DWDM device solution. Attached Figure Description

[0025] Figure 1 Top view of a dense wavelength division multiplexing (DWDM) device.

[0026] Figure 2 This is a bottom view of a dense wavelength division multiplexing (DWDM) device.

[0027] Figure 3 An isometric view of a dense wavelength division multiplexing device.

[0028] Figure 4 Isometric projection of dense wavelength division multiplexing devices from another perspective.

[0029] Figure 5 This is a schematic diagram of the optical path signal of a dense wavelength division multiplexing (DWDM) device.

[0030] Reference numerals: 100, Dense wavelength division multiplexing device; 110, Base plate; 120, Common-end fiber collimator; 130, Channel-end fiber collimator assembly; 131, First channel-end fiber collimator group; 132, Second channel-end fiber collimator group; 133, Third channel-end fiber collimator group; 134, Fourth channel-end fiber collimator group; 135, Fifth channel-end fiber collimator; 140, Optical assembly; 141, Filter assembly; 1411, Channel pre-separation filter; 1412, First filter group; 1413, Second filter group; 1414, Third filter group; 1415, Fourth filter group; 142, Skip plate; 143, First optical path; 144, Second optical path; 145, First reflector; 146, Second reflector; 147, Prism. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this utility model clearer, the present application will be further described in detail below with reference to the accompanying drawings. The described embodiments should not be regarded as limitations on this utility model. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0032] In the following description, references to "some embodiments" refer to a subset of all possible embodiments; however, it is understood that "some embodiments" may be the same or different subsets of all possible embodiments and may be combined with each other without conflict. Unless otherwise defined, all technical and scientific terms used in the embodiments of this utility model have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiments of this utility model belong. The terminology used in the embodiments of this utility model is for the purpose of describing the embodiments of this utility model only and is not intended to limit the utility model.

[0033] Those skilled in the art should understand that, in the following description of the embodiments of this utility model, the sequence of numbers does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this utility model.

[0034] The terminology used in the embodiments of this utility model is for the purpose of describing particular embodiments only and is not intended to be limiting of the utility model. The singular forms "a" and "the" as used in the embodiments of this utility model and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0035] To make the objectives, technical solutions, and advantages of this utility model clearer, the following description, in conjunction with the appendix to the specification, will be provided. Figures 1 to 5The present invention will be further described in detail below. It should be noted that these embodiments are only used to explain the present invention and are not intended to limit the scope of protection of the present invention.

[0036] This embodiment provides a dense wavelength division multiplexing device 100, including:

[0037] Base plate 110;

[0038] A common-end fiber optic collimator 120 is mounted on the base plate 110;

[0039] The channel-end fiber optic collimator assembly 130 is mounted on the base plate 110; and

[0040] Optical component 140 is disposed on base plate 110 and forms free space optical path. Optical component 140 is configured to split multi-wavelength optical signals incident from common end fiber collimator 120 via free space optical path and couple them to the corresponding fiber collimators in channel end fiber collimator component 130 respectively.

[0041] Optical assembly 140 includes dense wavelength division multiplexing filter assembly 141; filter assembly 141 includes at least one channel pre-separation filter 1411, configured to receive optical signals at an actual incident angle greater than the nominal application angle of the channel pre-separation filter 1411, such that the target wavelength filtered out by the channel pre-separation filter 1411 is different from its nominal wavelength at the nominal application angle.

[0042] In one specific embodiment, the dense wavelength division multiplexing (DWDM) device 100 provided in this embodiment has a base plate 110 as its main structure. A common-end fiber collimator 120 is mounted on the base plate 110 for inputting the multi-wavelength mixed optical signal to be demultiplexed. Simultaneously, a set of channel-end fiber collimator assemblies 130 is also arranged on the base plate 110 for receiving the individual single-wavelength channel optical signals after demultiplexing. An optical assembly 140 is also integrated on the base plate 110, which is precisely arranged to form a free-space optical path system. The core function of this optical system is to split, fold, and filter the multi-wavelength optical signal incident from the common-end fiber collimator 120 in free space, and finally precisely couple the separated channel optical signals to the corresponding fiber collimators in the channel-end fiber collimator assembly 130.

[0043] The core component of the optical assembly 140 is the dense wavelength division multiplexing (DWDM) filter assembly 141. In this embodiment, the filter assembly 141 includes at least one channel pre-separation filter 1411, and multiple subsequent sets of filters. The key to this embodiment is that at least one filter in the device 100 (e.g., the channel pre-separation filter 1411) is configured such that the actual incident angle of the received optical signal is designed to be significantly larger than the nominal application angle specified at the factory. For example, a filter with a nominal application angle of 1.8 degrees is designed in the device to operate at an actual incident angle greater than 5 degrees. Utilizing the physical characteristic that the center wavelength of a thin-film filter shifts towards shorter wavelengths as the incident angle increases, the target wavelength actually filtered by the filter differs from its nominal wavelength at the nominal angle. In this way, low-cost standardized devices can be used to achieve filtering of different target wavelengths by adjusting the optical path angle, thereby significantly reducing the material cost of the device.

[0044] In some embodiments, the channel pre-separation filter 1411 is disposed on the base plate 110 and located in the direct output optical path of the common end fiber collimator 120, for filtering out the first channel optical signal group from the incident multi-wavelength optical signal.

[0045] In one specific embodiment, this embodiment provides a more detailed description of the structure and function of the channel pre-separation filter 1411. For example... Figure 1 , Figure 3 and Figure 5 As shown, the channel pre-separation filter 1411 is fixed on the base plate 110, and its position in the optical path is precisely set directly in front of the common-end fiber collimator 120, i.e., in its direct outgoing optical path. Its function is to act as the first-stage filter before the optical signal enters the complex optical path, filtering out and separating the first channel optical signal group from all incident multi-wavelength optical signals. This design simplifies the number of wavelengths that subsequent optical paths need to process and provides a dedicated transmission path for this specific channel group.

[0046] In some embodiments, the optical component 140 further includes a jumper 142 disposed on the base plate 110 and located in the optical path after the channel pre-separation filter 1411, for dividing the incident multi-wavelength optical signal into a first transmitted optical path 143 and a second reflected optical path 144.

[0047] In one specific embodiment, such as Figure 1 , Figure 3 and Figure 5As shown, the optical assembly 140 also includes a jumper 142. The jumper 142 is fixed to the base plate 110, and its position in the optical path immediately follows the channel pre-separation filter 1411. After the mixed optical signal passes through the channel pre-separation filter 1411, the remaining mixed optical signal is incident on the jumper 142. The jumper 142 is a special filter that splits the incident light beam in two: one part of the optical signal passes through the jumper 142, forming the first transmitted optical path 143; the other part of the optical signal is reflected by the film layer of the jumper 142, forming the second reflected optical path 144. This design allows the optical path to be divided into upper and lower paths on the base plate 110, greatly improving space utilization and is one of the key structures for achieving device miniaturization.

[0048] In some embodiments, the optical component 140 further includes a first reflector 145 and a second reflector 146; the first reflector 145 is disposed adjacent to the transmission outlet of the jumper 142 and is used to perform a first reflection on the first optical path 143; the second reflector 146 is disposed in the first optical path 143 after the first reflection and is used to perform a second reflection to change the propagation direction of the first optical path 143.

[0049] In one specific embodiment, to further refine the optical path design, the optical assembly 140 also includes a first reflector 145 and a second reflector 146. For example... Figure 1 , Figure 3 and Figure 5 As shown, both mirrors are used to process the first optical path 143 transmitted by the jumper 142. The first mirror 145 is physically located adjacent to the transmission outlet of the jumper 142, and performs a first reflection of the first optical path 143 at approximately 90 degrees. After the first reflection, the light beam is directed towards the second mirror 146, which is positioned in the optical path after the first reflection, and performs a second reflection of the light beam at approximately 90 degrees. Through these two consecutive reflections, the overall propagation direction of the first optical path 143 is effectively changed, allowing it to be precisely guided to the subsequent target filtering area.

[0050] In some embodiments, the filter assembly 141 further includes a first filter group 1412, a second filter group 1413, a third filter group 1414, and a fourth filter group 1415; a first optical path 143 is guided by a second reflector 146 to pass sequentially through the first filter group 1412 and the second filter group 1413, the first optical path 143 filters out a second channel optical signal group through the first filter group 1412, and the first optical path 143 filters out a third channel optical signal group through the second filter group 1413; a second optical path 144 is directly guided to pass sequentially through the third filter group 1414 and the fourth filter group 1415, the second optical path 144 filters out a fourth channel optical signal group through the third filter group 1414, and the second optical path 144 filters out a fifth channel optical signal group through the fourth filter group 1415.

[0051] In one specific embodiment, the configuration and optical path allocation of the filter assembly 141 are described in detail. For example... Figure 1 , Figure 3 and Figure 5 As shown, in addition to the channel pre-separation filter 1411, the filter assembly 141 also includes a first filter group 1412, a second filter group 1413, a third filter group 1414, and a fourth filter group 1415.

[0052] The first optical path 143, after being reflected twice by the second reflector 146, is guided to pass sequentially through the first filter group 1412 and the second filter group 1413 located in its optical path. When the light beam passes through the first filter group 1412, it filters out the second channel optical signal group; when it passes through the second filter group 1413, it filters out the third channel optical signal group.

[0053] Meanwhile, the second optical path 144, formed by direct reflection from the jumper 142, is directly guided to pass sequentially through the third filter group 1414 and the fourth filter group 1415 located on its optical path. When the light beam passes through the third filter group 1414, it filters out the fourth channel optical signal group; when it passes through the fourth filter group 1415, it filters out the fifth channel optical signal group.

[0054] In some embodiments, the optical component 140 further includes a prism 147 fixed to one side of the base plate 110, and the prism 147 is configured to intercept and reflect the first channel optical signal group, the third channel optical signal group and the fifth channel optical signal group to the back side of the base plate 110.

[0055] In one specific embodiment, the optical component 140 further includes a prism 147. For example... Figures 1 to 5As shown, the prism 147 is fixed to one side of the base plate 110, and its physical position determines its interception range. In this embodiment, the prism 147 is precisely configured to achieve uniform reflection of several specific groups of channel optical signals. Specifically, it is configured to intercept and reflect the first group of channel optical signals filtered by the channel pre-separation filter 1411, the third group of channel optical signals filtered by the second filter group 1413, and the fifth group of channel optical signals filtered by the fourth filter group 1415. These three groups of optical signals are uniformly reflected to the back of the base plate 110 by the prism 147 when they reach the side of the base plate 110.

[0056] In some embodiments, the channel-end fiber collimator assembly 130 includes a first channel-end fiber collimator group 131, a second channel-end fiber collimator group 132, a third channel-end fiber collimator group 133, a fourth channel-end fiber collimator group 134, and a fifth channel-end fiber collimator 135.

[0057] The first channel fiber collimator group 131 and the second channel fiber collimator group 132 are disposed on the front side of the base plate 110. The first channel fiber collimator group 131 receives the second channel optical signal group, and the second channel fiber collimator group 132 receives the fourth channel optical signal group.

[0058] The third-channel fiber collimator group 133, the fourth-channel fiber collimator group 134, and the fifth-channel fiber collimator 135 are all located on the back of the base plate 110. The third-channel fiber collimator group 133 receives the third-channel optical signal group, the fourth-channel fiber collimator group 134 receives the fifth-channel optical signal group, and the fifth-channel fiber collimator 135 receives the first-channel optical signal group.

[0059] In one specific embodiment, this embodiment describes the detailed configuration and layout of the channel-end fiber collimator assembly 130. For example... Figures 1 to 4 As shown, the channel-end fiber optic collimator assembly 130 specifically includes a first channel-end fiber optic collimator group 131, a second channel-end fiber optic collimator group 132, a third channel-end fiber optic collimator group 133, a fourth channel-end fiber optic collimator group 134, and a single fifth channel-end fiber optic collimator 135.

[0060] These collimator groups are arranged in two sections: the first channel-end fiber optic collimator group 131 and the second channel-end fiber optic collimator group 132 are mounted on the front of the base plate 110. The first group 131 is used to directly receive the second channel optical signal group filtered by the first filter group 1412; the second group 132 is used to directly receive the fourth channel optical signal group filtered by the third filter group 1414.

[0061] The remaining collimator assemblies are mounted on the back of the base plate 110, such as... Figure 2 and Figure 4 As shown in the diagram, the third-channel fiber collimator group 133 receives the third-channel optical signal group reflected by prism 147; the fourth-channel fiber collimator group 134 receives the fifth-channel optical signal group reflected by prism 147; and the fifth-channel fiber collimator 135 receives the first-channel optical signal group reflected by prism 147. This three-dimensional layout combining front and back sides achieves efficient, crosstalk-free output of all channel signals.

[0062] In some embodiments, the base plate 110 is made of ceramic material or alloy material with a low coefficient of thermal expansion, and its surface is provided with stepped structures or engravings for bearing and precise positioning.

[0063] In one specific embodiment, the material selection of the base plate 110, which serves as the carrier for all optical elements, is crucial for ensuring the long-term stability and reliability of the device. The base plate 110 is preferably made of ceramic material due to its excellent dimensional stability and insulation. Alternatively, an alloy material with a low coefficient of thermal expansion, such as Kovar alloy or Invar alloy, can be used to minimize optical path collimation errors caused by changes in ambient temperature. To ensure that all optical elements can be precisely and securely mounted, the surface of the base plate 110 is precision-machined with stepped structures or etched lines for support and precise positioning.

[0064] In some embodiments, the prism 147 is a roof-shaped prism 147 with an isosceles trapezoidal cross-section.

[0065] In one specific embodiment, the prism 147 used to uniformly reflect a specific optical path to the back side is specifically a roof-shaped prism. Viewed from the side, its cross-section is an isosceles trapezoid. This special shape design facilitates aberration-free, equal-path reflection of multiple parallel optical signals, ensuring signal transmission quality.

[0066] In some embodiments, the nominal application angle is 1.8 degrees, and the actual incident angle is greater than 5 degrees.

[0067] In one specific embodiment, the filter in device 100 (such as channel pre-separation filter 1411) has a nominal application angle of 1.8 degrees as designed at the factory. However, in the optical path design of this device, its actual incident angle is set to be greater than 5 degrees. It is this significant difference in angle that causes a short shift in the filter center wavelength, thereby allowing designers to utilize this characteristic to achieve diverse filtering functions with low-cost, standardized devices.

[0068] Working principle of this utility model

[0069] The dense wavelength division multiplexing device 100 disclosed in this utility model has the core working principle of creatively combining free space optical path integration technology, the "angle-wavelength" drift physical characteristics of thin film filtering, optical path spatial segmentation and folding technology, and three-dimensional output layout, thereby fundamentally solving the three major bottlenecks of size, cost and integration in traditional TFF (thin film filtering) technology in multi-channel applications.

[0070] 1. Core Physical Principle: Application of the Angle-Wavelength Drift Effect in Thin-Film Filtering

[0071] This is the key principle behind the low-cost implementation of this utility model.

[0072] A standard thin-film interferometer (TFF) filter is designed and manufactured with a nominal application angle, such as 1.8 degrees. At this angle, it can accurately filter its corresponding nominal center wavelength. Physics dictates that when an optical signal is incident on the filter at an actual angle of incidence greater than its nominal application angle, the filtered center wavelength will "drift" towards shorter wavelengths.

[0073] 2. Device Architecture Principle: Free-space optical path integration based on a single substrate

[0074] This invention abandons the outdated approach of cascading multiple discrete devices with optical fibers in the traditional TFF scheme. Its architecture is based on building a complete free space optical path system on a single base plate 110.

[0075] All optical components, including the common-end fiber collimator 120, filter assembly 141, jumper 142, mirrors 145 and 146, prism 147, and channel-end fiber collimator assembly 130, are precisely fixed on the same base plate 110. The optical signal detaches from the fiber and propagates, folds, filters, and couples in the free space above the base plate as a parallel beam. This "on-chip optical system" design directly results in a highly compact and integrated structure, fundamentally solving the problems of large size and complex packaging in cascaded solutions.

[0076] 3. Optical path layout principles: spatial segmentation, path folding, and serial filtering

[0077] In order to accommodate as many channels as possible within a limited base plate area, this invention employs an optical path layout:

[0078] First-stage preprocessing: After the light exits from the common-end collimator 120, it first passes through the channel pre-separation filter 1411, which pre-separates a specific channel (the first channel optical signal group). This is equivalent to setting up a "priority exit" on the main road, simplifying the complexity of the subsequent main path.

[0079] Spatial segmentation: The pre-processed residual optical signal is incident on the jumper 142. The jumper is essentially a beam splitter that divides the optical path into two: a first transmitted optical path 143 and a second reflected optical path 144. This directly doubles the channel processing capability of the device in space.

[0080] Path folding: For the first optical path 143, two consecutive 90-degree reflections are performed using the first reflecting mirror 145 and the second reflecting mirror 146. This is not a simple turning, but rather a "Z"-shaped folding of the optical path. It allows a long optical path to be "compressed" into a very small physical area, which is a key technique for achieving device miniaturization.

[0081] Serial filtering: Whether it is the folded first optical path 143 or the directly propagating second optical path 144, they pass through two sets of filters in sequence (for example, the first optical path 143 passes through the first filter group 1412 and the second filter group 1413 in sequence). This allows the beam to "strip" one or a group of specific wavelengths each time it passes through a filter, ultimately achieving complete separation of all wavelengths.

[0082] 4. Output structure principle: a three-dimensional layout combining front and back sides.

[0083] This invention utilizes prism 147 as a "three-dimensional skybridge" for an optical path.

[0084] After filtering is completed on the front of the base plate, a portion of the optical signals (the second and fourth optical signal groups) are directly received by the first and second channel optical fiber collimator groups 131 and 132 installed on the front.

[0085] The other part of the optical signals (the first optical signal group, the third optical signal group, and the fifth optical signal group) are uniformly intercepted by prism 147 at the end of the optical path and reflected as a whole to the back of the base plate.

[0086] On the back of the base plate, the third-channel fiber collimator group 133, the fourth-channel fiber collimator group 134, and the fifth-channel fiber collimator 135 are pre-installed to accurately receive the light signals reflected from the front through the prism 147.

[0087] By combining the front and back sides in a three-dimensional output design, this invention greatly increases the available space for port layout, effectively avoids the crowding and interference that may occur when a large number of output optical fibers are on the same plane, and achieves higher integration and a cleaner structure. Specific Implementation

[0089] I. Theory and Practical Application of the "Angle-Wavelength Drift Effect"

[0090] (1) Theoretical basis and mathematical model

[0091] The core theoretical basis for this invention's low-cost design utilizing the "angle-wavelength drift effect" stems from the optical properties of thin-film interference filters (TFFs). When light enters the filter at an angle different from perpendicular incidence, its center wavelength will "drift" towards shorter wavelengths. This physical phenomenon can be precisely described by the following formula:

[0092]

[0093] Where: λ θ λ0 represents the actual center wavelength of the filter when the incident angle is θ; λ0 represents the nominal center wavelength of the filter at 0 degrees when the light is incident perpendicularly (θ = 0°); n eff θ is the equivalent refractive index of the multilayer film system of the filter. In the calculation of this utility model, according to the typical data provided by a mainstream filter manufacturer, this value is taken as 1.585589; θ is the actual incident angle of the optical signal entering the filter.

[0094] (2) Specific numerical calculation example: implementation from CH15 to CH18

[0095] To illustrate the practical application of the above principle more specifically, a computational example is provided to implement the CH18 channel filtering function from the CH15 filter.

[0096] Design objective: To filter out channel CH18 in the ITU-T standard, whose corresponding center wavelength is 1563.047nm (i.e., target wavelength). θ ).

[0097] Standardized components selected: A low-cost CH15 filter is used, with a nominal center wavelength of 1565.496 nm (i.e., λ) when incident on a conventional three-port device (θ = 1.8°). θ＝1.8 ), and λ0 is calculated using the formula.

[0098] Calculation process: The above λ θ , λ0 and n eff By substituting the value into the formula, the required actual incident angle θ can be solved.

[0099] Calculation results: According to the formula, an actual incident angle of θ = 5.396 degrees is required to accurately shift the center wavelength of the CH15 filter from 1565.496nm to 1563.047nm, thereby achieving the filtering effect of CH18.

[0100] This calculation result strongly verifies that the "design with an angle greater than 5 degrees" in this utility model has sufficient scientific basis and is completely feasible in engineering. Its core idea is: if a filter with the nominal wavelength is used directly and a large angle of incidence is adopted, the center wavelength will be too short; therefore, by pre-selecting a filter with a nominal wavelength that is too long, and then using a large angle of incidence to make its wavelength drift to a shorter wavelength, it can eventually be accurately returned to the target wavelength we need.

[0101] (3) Geometric advantages of large-angle design

[0102] The large-angle design of more than 5 degrees not only enables the wavelength tuning function mentioned above, but also brings significant geometric advantages, which helps to miniaturize the device and improve process stability.

[0103] Based on geometric relationships, it can be simplified to a right-angled triangle model: the incident point of the filter is the vertex, the direction of light propagation is the hypotenuse, and the angle between the optical axis and the normal to the filter is the incident angle θ. When keeping the distance of light propagation (the length of the hypotenuse) constant, according to the tangent function, the larger the incident angle θ, the greater the displacement of the light spot on the filter relative to the optical axis.

[0104] In practical multi-channel arrays, this means:

[0105] Using a nominal 1.8-degree small angle: the light spots of adjacent channels will be very dense on the filter array, requiring extremely high positioning accuracy of the components, and the physical space is very limited.

[0106] Using a large angle of 5.3 degrees, the physical distance between adjacent channel light spots can be increased by nearly 2 times. This increased distance greatly improves the tolerance during production and assembly, reduces the alignment accuracy requirements, and also provides more physical space for the arrangement of other micro-optical components such as mirrors, thus making the overall structural design more compact and reliable.

[0107] This invention utilizes this physical effect. For example, the technical solution requires filtering out an optical signal with a target wavelength of CH18 (International Telecommunication Union standard channel number). According to conventional methods, in optical path designs requiring large-angle incident light, it is necessary to expensively customize a CH18 filter specifically for large angles from the manufacturer.

[0108] The present invention employs a different approach: instead of using a custom-designed CH18 filter, a low-cost, standardized, mass-produced CH15 filter (whose nominal wavelength is three channel intervals longer than that of CH18) is selected. Then, through precise optical path design, the mixed optical signal is incident on this CH15 filter at a calculated large angle (e.g., greater than 5 degrees). Due to the increased incident angle, the center wavelength of the CH15 filter precisely shifts three channel intervals towards the shorter wavelength, ultimately achieving the perfect filtering of the target wavelength of CH18.

[0109] II. Specific Channel Allocation and Optical Path Mapping Examples

[0110] This specific embodiment provides a detailed wavelength allocation scheme for a 16-channel device, clearly demonstrating the complete path of the optical signal in each channel:

[0111] Initial state: The mixed optical signal incident from the common-end fiber collimator 120 contains 16 channels from CH18 to CH33.

[0112] The details of the optical path allocation are as follows:

[0113] First optical path 143, upper transmission optical path:

[0114] CH27, CH29, CH31, and CH33 are filtered out sequentially through the first filter group 1412 and directly received on the front by the first channel end fiber collimator group 131.

[0115] After passing through the second filter group 1413, CH28, CH30, and CH32 are filtered out in sequence. Their optical paths are reflected by the prism 147 to the back of the base plate and received by the third channel end fiber collimator group 133.

[0116] Second optical path 144, lower reflected optical path:

[0117] The light beam passes through the third filter group 1414 and moves away from the common end fiber collimator 120 in sequence. CH26, CH18, CH20, CH22, and CH24 are filtered out in sequence and are directly received by the second channel end fiber collimator group 132 at the front.

[0118] After passing through the fourth filter group 1415, CH19, CH21, and CH23 are filtered out in sequence. Their optical paths are reflected by the prism 147 to the back of the base plate and received by the fourth channel end fiber collimator group 134.

[0119] After passing through the channel pre-separation filter group 1411, the optical path of CH25 is reflected by the prism 147 to the back of the base plate and received by the fifth channel end fiber collimator 135.

[0120] This specific channel mapping diagram fully demonstrates how this embodiment efficiently and orderly achieves the separation and reception of all 16 channel signals through optical path segmentation, serial filtering, and a three-dimensional output layout on both sides.

[0121] The above description describes specific embodiments of this utility model. Through the above structural design, this utility model successfully overcomes the shortcomings of the prior art and provides a high-performance, small-size, low-cost multi-channel dense wavelength division multiplexing device. It should be understood that those skilled in the art, under the guidance of the technical solution of this utility model, can make various other corresponding changes and modifications, and these changes and modifications should all fall within the protection scope of the claims of this utility model.

Claims

1. A dense wavelength division multiplexing device, characterized by, include: Base plate; A common-end fiber optic collimator is mounted on the base plate; The channel-end fiber optic collimator assembly is mounted on the base plate; as well as An optical component is disposed on the base plate and forms a free space optical path. The optical component is configured to split a multi-wavelength optical signal incident from the common end fiber collimator via the free space optical path and couple it to the corresponding fiber collimator in the channel end fiber collimator assembly. The optical component includes a dense wavelength division multiplexing (DWDM) filter assembly; the filter assembly includes at least one channel pre-separation filter configured to receive an optical signal at an actual incident angle greater than the nominal application angle of the channel pre-separation filter, such that the target wavelength filtered out by the channel pre-separation filter is different from its nominal wavelength at the nominal application angle.

2. The device of claim 1, wherein, The channel pre-separation filter is disposed on the base plate and located in the direct output optical path of the common end fiber collimator, and is used to filter out the first channel optical signal group from the incident multi-wavelength optical signal.

3. The device of claim 2, wherein, The optical component also includes a jumper, which is disposed on the base plate and located in the optical path after the channel pre-separation filter, for dividing the incident multi-wavelength optical signal into a first transmitted optical path and a second reflected optical path.

4. The device of claim 3, wherein, The optical component further includes a first reflector and a second reflector; the first reflector is disposed adjacent to the transmission outlet of the jumper and is used to perform a first reflection on the first optical path; the second reflector is disposed in the first optical path after the first reflection and is used to perform a second reflection to change the propagation direction of the first optical path.

5. The device of claim 4, wherein, The filter assembly further includes a first filter group, a second filter group, a third filter group, and a fourth filter group; the first optical path is guided by the second reflector to pass sequentially through the first filter group and the second filter group, the first optical path filters out a second channel optical signal group through the first filter group, and the first optical path filters out a third channel optical signal group through the second filter group; the second optical path is directly guided to pass sequentially through the third filter group and the fourth filter group, the second optical path filters out a fourth channel optical signal group through the third filter group, and the second optical path filters out a fifth channel optical signal group through the fourth filter group.

6. The device of claim 5, wherein, The optical component also includes a prism fixed to one side of the base plate, the prism being configured to intercept and reflect the first channel optical signal group, the third channel optical signal group, and the fifth channel optical signal group to the back side of the base plate.

7. The device of claim 6, wherein, The channel-end fiber optic collimator assembly includes a first channel-end fiber optic collimator group, a second channel-end fiber optic collimator group, a third channel-end fiber optic collimator group, a fourth channel-end fiber optic collimator group, and a fifth channel-end fiber optic collimator. The first channel-end fiber collimator group and the second channel-end fiber collimator group are disposed on the front side of the base plate. The first channel-end fiber collimator group receives the second channel optical signal group, and the second channel-end fiber collimator group receives the fourth channel optical signal group. The third-channel fiber collimator group, the fourth-channel fiber collimator group, and the fifth-channel fiber collimator are all disposed on the back of the base plate. The third-channel fiber collimator group receives the third-channel optical signal group, the fourth-channel fiber collimator group receives the fifth-channel optical signal group, and the fifth-channel fiber collimator receives the first-channel optical signal group.

8. The device of claim 1, wherein, The base plate is made of ceramic material or alloy material with low thermal expansion coefficient, and its surface is provided with stepped structures or engravings for bearing and precise positioning.

9. The device of claim 6, wherein, The prism is a roof-shaped prism with an isosceles trapezoidal cross-section.

10. The device of claim 1, wherein, The nominal application angle is 1.8 degrees, and the actual incident angle is greater than 5 degrees.

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