Light guide sheet of optical fiber attenuator, optical fiber attenuator and attenuation method

Abstract

The invention relates to the technical field of optical fiber attenuators, in particular to a light guide plate of an optical fiber attenuator, the optical fiber attenuator and an attenuation method, which have the characteristics that the absolute value of a thermal optical coefficient is less than or equal to 2.0 * 10 <-4 > / DEG C, and the deviation of a preset attenuation value can be kept within + / -0.1 dB when the network access optical power fluctuates by + / -3dB; the laser damage threshold is not lower than 10kW / cm < 2 >, and the device is used for supporting online attenuation and monitoring of high-power optical signals. According to the invention, the thermal stability and the laser damage resistance of the material are greatly improved through the cooperative limitation of the thermal optical coefficient and the laser damage threshold of the light guide sheet, and the attenuation fluctuation caused by temperature excursion cannot be generated in a high-power light field environment; meanwhile, an interface self-adaptive filling mechanism is constructed by using a specific Young modulus, an air gap at an optical fiber joint is thoroughly eradicated through flexible rheology under a standard insertion and extraction force, and reverse echoes caused by sudden change of an interface refractive index are eliminated from a physical source.

Description

Technical Field

[0001] This invention relates to the field of fiber optic attenuator technology, and in particular to a light guide plate, a fiber optic attenuator, and an attenuation method for a fiber optic attenuator. Background Technology

[0002] With the widespread adoption of AI applications, the advancement of FTTR (Fiber to the Reach) construction, and the research and development of 5.5G and 6G communication technologies, fiber optic communication networks are entering the era of ultra-high bandwidth transmission of 400G-800G. The demand for high-speed and high-bandwidth transmission places extremely stringent requirements on the transmission quality of optical networks. During optical transmission, attenuators need to be installed at the active connection points of the optical fiber to adjust the optical power in order to match the power compatibility between the optical transmitter and receiver.

[0003] Existing adapter-type fiber optic attenuators mostly employ a method of placing metal isolators at the active connection points. Optical power attenuation is achieved by creating an air gap between the fiber optic connectors. This method has significant technical drawbacks: Firstly, when light waves enter the air medium from the fiber core, they generate strong back echoes. The PC / UPC type active fiber optic connection schemes widely used in current communication networks have insufficient upper limits for return loss. The back echoes cause interference between the reflected light and the original signal light, leading to signal power fluctuations and increased bit error rate. Simultaneously, the reflected light returning to the laser interferes with its resonant cavity, causing instability in laser output power and wavelength, and even accelerating laser aging. The superimposed return loss also increases the actual link loss, shortening the transmission distance and failing to meet the transmission requirements of hundreds of gigabits of bandwidth. Secondly, the presence of the air gap makes the optical path attenuation value susceptible to environmental vibrations, insertion / removal operations, and other factors, resulting in poor attenuation accuracy and stability, making it difficult to adapt to the power control requirements of high-bandwidth transmission.

[0004] Furthermore, existing attenuation control methods are too crude and simplistic. Currently, most methods rely solely on "spatial divergence" for attenuation, lacking effective constraints on the beam's microscopic level. This prevents the construction of effective optical mismatch interfaces (such as lateral refractive index barriers) to physically shrink the mode field diameter, resulting in insufficient control precision and linearity to meet precise control requirements. Simultaneously, existing attenuators lack targeted physicochemical performance design for their functional components. Key indicators such as thermo-optical coefficients, Young's modulus, and laser damage threshold are not matched to high-power transmission environments, leading to temperature drift deviations and even physical damage under high-power irradiation. Moreover, this crude longitudinal attenuation structure is often completely isolated from online detection and positioning modules, making it difficult to efficiently capture minute spilled light. Maintenance personnel cannot read attenuation values ​​and service status in real time without network interruption, leaving the system in a "blind adjustment" and "black box" state for extended periods, resulting in extremely high maintenance costs.

[0005] In summary, there is an urgent need to develop an optical fiber attenuator with precise physicochemical performance parameters and mode field control structure, which can eliminate interface return loss, achieve high-precision and high-stability attenuation control in high-power environments, and integrate online intelligent monitoring and remote positioning functions. Summary of the Invention

[0006] In this section, as well as in the abstract and title of this application, some simplifications or omissions may be made to avoid obscuring the purpose of this section, the abstract, and the title of this application, and such simplifications or omissions shall not be used to limit the scope of the invention.

[0007] To address the problem of high return loss caused by "air gaps" in existing fiber optic attenuators, one objective of this invention is to provide a light guide sheet for a fiber optic attenuator.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: a light guide sheet for an optical fiber attenuator, having an absolute value of thermo-optical coefficient ≤ 2.0 × 10⁻⁶. -4 / ℃, ensuring that the deviation of its preset attenuation value remains within ±0.1dB when the input optical power fluctuates by ±3dB; the laser damage threshold is not less than 10kW / cm 2 This is used to support online attenuation and monitoring of high-power optical signals.

[0009] As a preferred embodiment of the light guide sheet of the optical fiber attenuator of the present invention, the light guide sheet has a total light transmittance of ≥98.5% in the communication band range of 1310nm to 1625nm, and its haze is ≤0.2%.

[0010] As a preferred embodiment of the light guide sheet of the optical fiber attenuator of the present invention, the light guide sheet has a Young's modulus between 1.5 and 8.0 MPa, so that the material can cover the end face gap of more than 10 μm under a standard insertion and extraction force of 5 N to 15 N.

[0011] The beneficial effects of the optical guide sheet of the fiber optic attenuator of the present invention are as follows: By synergistically limiting the thermo-optic coefficient and laser damage threshold of the optical guide sheet, the thermal stability and laser damage resistance of the material are greatly improved, ensuring that attenuation fluctuations caused by temperature drift will not occur in high-power optical field environments, and the deviation is strictly locked within ±0.1dB; at the same time, an interface adaptive filling mechanism is constructed by using a specific Young's modulus, and the "air gap" at the fiber connection is completely eliminated by flexible rheology under standard insertion and extraction force, eliminating the back echo caused by the sudden change of interface refractive index from the physical source, solving the signal interference problem caused by insufficient return loss reserve in high-speed transmission systems, and significantly ensuring the transmission stability of ultra-high-speed fiber optic links.

[0012] To address the shortcomings of existing fiber optic attenuators, such as high return loss due to "air gaps," low accuracy due to limited control methods, and inability to monitor online, another objective of this invention is to provide a fiber optic attenuator.

[0013] To achieve the above objectives, the present invention adopts the following technical solution: an optical fiber attenuator, comprising an alignment sleeve disposed within the attenuator and a light guide plate disposed on the alignment sleeve; the light guide plate is transversely intersecting the optical path channel of the alignment sleeve and has a preset thickness or preset refractive index to construct an optical mismatch interface in the optical path, thereby causing the optical signal passing through the light guide plate to generate a predetermined decibel power attenuation.

[0014] In a preferred embodiment of the optical fiber attenuator of the present invention, the outer diameter of the light guide plate is matched with the inner diameter of the alignment sleeve.

[0015] In a preferred embodiment of the optical fiber attenuator of the present invention, the light guide sheet is a homogeneous structure, and the refractive index of the light guide sheet is the same as or similar to the core refractive index of the optical fiber. The light guide sheet is configured to adjust the attenuation by adjusting its thickness along the optical path channel axis.

[0016] In a preferred embodiment of the optical fiber attenuator of the present invention, the light guide is a homogeneous structure, and the refractive index of the light guide is different from the refractive index of the fiber core of the coupled optical fiber. The light guide is configured to adjust the attenuation by means of the refractive index difference between the light guide and the fiber core.

[0017] In a preferred embodiment of the fiber optic attenuator of the present invention, the light guide sheet is a heterogeneous composite structure, comprising a support plate and a flexible light guide material disposed on the support plate; a light guide hole located on the optical path channel axis is formed on the support plate, the flexible light guide material is filled in the light guide hole to form a flexible light guide channel, and the flexible light guide material extends to cover the side of the support plate.

[0018] As a preferred embodiment of the fiber optic attenuator of the present invention, wherein: the hole wall of the light guide hole forms a lateral refractive index barrier through the refractive index difference between the support plate and the flexible light guide material; wherein, the lateral refractive index barrier is configured to: forcibly compress the light beam passing through the flexible light guide channel by radially constraining the optical waveguide mode to produce a physical contraction of the mode field diameter, thereby achieving attenuation through mode field mismatch on the output side.

[0019] In a preferred embodiment of the fiber optic attenuator of the present invention: a radially penetrating slot is provided on the alignment sleeve; the light guide includes a light guide tongue that extends from the outside of the alignment sleeve through the slot and laterally cuts off the optical path, and a light guide body located outside the alignment sleeve and connected to the light guide tongue; the light guide is engaged with the periphery of the slot at the junction of the light guide body and the light guide tongue; the attenuator has a receiving cavity communicating with the slot, and the light guide body is disposed in the receiving cavity.

[0020] In a preferred embodiment of the fiber optic attenuator of the present invention, the light guide is provided with a photosensitive element, which is used to capture and sense the overflow light signal that overflows from the flexible light guide channel and is transmitted outward through the light guide sheet.

[0021] In a preferred embodiment of the fiber optic attenuator of the present invention, the light guide is provided with a monitoring interface for exporting the electrical signal of the photosensitive element. The monitoring interface is configured to calculate and feed back the online attenuation value of the attenuator in real time based on the intensity of the light signal captured by the photosensitive element.

[0022] As a preferred embodiment of the fiber optic attenuator of the present invention, wherein: a grating with a unique reflective feature is etched or implanted in the flexible light guide channel, and the grating is used to remotely locate the line position where the attenuator is located.

[0023] The fiber optic attenuator of this invention offers the following advantages: By employing a homogeneous or heterogeneous composite light guide structure, multi-dimensional attenuation control can be flexibly achieved by adjusting the thickness and refractive index difference according to actual needs. Furthermore, the heterogeneous composite structure can induce a physical contraction of the mode field diameter through a lateral refractive index barrier, achieving high linearity and high precision energy stripping through microscopic mode field mismatch. This completely overcomes the limitations of traditional methods that rely solely on spatial divergence leading to uneven attenuation, greatly enriching attenuation control methods and improving the accuracy, range, and applicability in high-bandwidth transmission environments.

[0024] To address the shortcomings of existing fiber optic attenuators, such as high return loss due to "air gaps," low accuracy due to limited control methods, and inability to monitor online, another objective of this invention is to provide an attenuation method for fiber optic attenuators.

[0025] To achieve the above objectives, the present invention adopts the following technical solution: an attenuation method for an optical fiber attenuator, comprising inserting two optical fiber connectors into an alignment sleeve, causing the connector end faces to press against a light guide sheet, utilizing the elastic rheological changes generated by the pressure on the light guide sheet to displace interfacial air and fill the end face gap; utilizing the preset thickness, preset refractive index, or lateral refractive index barrier of the light guide sheet to construct an optical mismatch interface in the optical path, causing power attenuation of the optical signal passing through the light guide sheet; using a photosensitive element to capture the overflow optical signal transmitted outward through the light guide sheet in real time to provide feedback on the real-time attenuation value, and using a grating embedded in a flexible light guide channel for remote positioning.

[0026] The attenuation method of the optical fiber attenuator of the present invention has the same beneficial effects as that of the optical fiber attenuator, and will not be repeated here. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the optical path channel, alignment sleeve, and light guide sheet of the present invention.

[0029] Figure 2 This is a schematic diagram of the alignment sleeve and light guide sheet of the present invention.

[0030] Figure 3 This is a light path diagram when the light guide sheet of the present invention has a homogeneous structure.

[0031] Figure 4 This is a schematic diagram of the flexible catheter channel of the present invention.

[0032] Figure 5 This is a schematic diagram of the support plate and light guide hole of the present invention.

[0033] Figure 6 This is a light path diagram when the light guide sheet of the present invention has a heterogeneous composite structure.

[0034] Figure 7 This is a cross-sectional view of the present invention.

[0035] Figure 8 This is a schematic diagram of the structure of the light guide tongue and alignment sleeve of the present invention.

[0036] Figure 9 This is a schematic diagram of the overall exploded structure of the present invention.

[0037] Figure 10This is a schematic diagram of the overall structure of the present invention. Detailed Implementation

[0038] To make the objectives, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0039] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0040] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0041] Example 1

[0042] Reference Figure 1 This embodiment provides a core component of an optical fiber attenuator 200—a light guide sheet 100.

[0043] Among them, the light guide 100 is the core component of the fiber optic attenuator 200 in this solution. In order to meet the stringent requirements for precise control of optical power and long-term stability in optical communication networks, the optical, thermal and mechanical basic parameters of the light guide 100 in this embodiment have been strictly configured.

[0044] This solution first eliminates uncontrollable random losses (such as Fresnel reflections caused by air) through perfect microscopic physical bonding, and then introduces a quantitative, stable and pure attenuation value by precisely controlling specific physical quantities of the light guide sheet 100 (such as preset axial thickness or preset refractive index difference). This design completely avoids the technical pain point of traditional attenuators 200 where the attenuation value drifts with environmental vibrations due to air gaps at the end face.

[0045] Based on the above design logic, the light guide 100 is configured to have the following key parameters: The absolute value of the thermo-optical coefficient is ≤2.0×10. -4 / ℃: Because the light guide 100 attenuates the light in the optical path, some optical energy (such as the partial absorption or scattering of high-power signals) is converted into localized heat. The extremely low thermo-optical coefficient ensures that the refractive index of the light guide material (or its internally encapsulated matching medium) does not significantly shift when heated. This ensures that even under drastic fluctuations in the input optical power (e.g., burst pulses of ±3dB), the preset attenuation value (e.g., 5dB, 10dB) of the light guide 100 remains within a very small range of ±0.1dB, achieving excellent temperature stability.

[0046] Laser damage threshold of not less than 10kW / cm²: With the continuous increase in the power of 400G / 800G and long-distance transmission of backbone networks, the optical power density borne by the attenuation interface is extremely high. This damage threshold ensures that the light guide 100 does not carbonize, melt, or discolor under continuous bombardment of high-power optical signals, perfectly supporting the online attenuation and long-term monitoring of high-power optical signals.

[0047] With a total light transmittance ≥98.5% and haze ≤0.2% (for communication bands from 1310nm to 1625nm): The light guide sheet 100 of this invention does not achieve attenuation by doping the material with random turbid impurities (impurities lead to uncontrollable light scattering and high return loss). Its substrate itself is configured to have extremely high optical purity (extremely low haze). The attenuation is entirely dependent on the "beam divergence caused by the preset thickness" or "precise medium refractive index mismatch" detailed in the subsequent embodiments, thereby achieving precise attenuation without compromising the waveform integrity of the optical signal and ensuring extremely high signal fidelity.

[0048] To achieve the aforementioned goal of "perfect fit first, then precise attenuation," this embodiment further strictly limits the mechanical properties of the light guide 100: the Young's modulus of the light guide 100 (or its flexible outer layer structure) is configured to be between 1.5 and 8.0 MPa. This range of elastic modulus represents a golden balance between "mechanical fatigue resistance" and "microscopic conformal rheology."

[0049] Because the standard fiber optic connector 500 (such as the UPC end face) is a slightly convex spherical surface, when the connector 500 is inserted and subjected to a standard insertion and extraction spring force of 5 N to 15 N, the light guide sheet 100 with this modulus can produce extremely sensitive microscopic deformation without structural breakage. This deformation displacement can not only completely cover the annular geometric gap of more than 10 μm caused by the spherical curvature of the connector 500 end face, but also, under the physical mechanism of "fluid equalization," squeeze out all the air at the contact interface like an optical fluid, perfectly filling nanoscale polishing scratches. Through this extremely close mechanical configuration and fluid equalization mechanism, the light guide sheet 100 reconstructs the irregular interface of 'air-fiber end face', which was originally prone to random Fresnel reflection, into a tightly wrapped optical path with continuously matched refractive index, composed of 'fiber end face - flexible outer film - internal matching paste - flexible outer film - fiber end face'. This structural transformation completely eliminates the uncontrollable fluctuations caused by the air gap, making the attenuation behavior of the optical signal at this point entirely controllable by the preset parameters of the light guide 100 itself (such as preset axial thickness or medium refractive index difference), thereby achieving fixed attenuation accuracy and stability.

[0050] The light guide 100 employs a composite cavity structure of "flexible outer film + internal matching paste". Specifically, its outer layer is a micro-closed flexible outer film made of a highly elastic, extremely thin polymer material with extremely high light transmittance (its physical deformation properties are similar to those of high-elastic medical latex or ultra-thin polyurethane film), exhibiting excellent tear resistance and ductility; its interior is filled and encapsulated with optical refractive index matching paste. This composite structure utilizes the incompressibility and pressure equalization characteristics of the internal fluid, as well as the extremely conformal characteristics of the outer film, allowing the light guide 100 to actively penetrate and perfectly fill the microscopic irregularities on the end face of the connector 500, much like an "optical fluid". Furthermore, the outer film effectively isolates the matching paste, preventing contamination of the fiber end face caused by repeated insertion and removal.

[0051] Example 2

[0052] Reference Figures 1-2 This embodiment provides an optical fiber attenuator 200, including an alignment sleeve 201 disposed within the attenuator 200 and a light guide 100 disposed on the alignment sleeve 201; the light guide 100 is transversely intersecting the optical path channel A of the alignment sleeve 201 and has a preset thickness L or a preset refractive index n, so as to construct an optical mismatch interface in the optical path, so that the optical signal passing through the light guide 100 generates a predetermined decibel power attenuation.

[0053] This solution utilizes the mechanical properties of the light guide 100, which combines a flexible outer film with internal fluid pressure equalization, to perfectly conform to and eliminate all residual air at the fiber end face. This completely eliminates the severe and uncontrollable random Fresnel reflections caused by air gaps (the culprit behind the drift of the traditional attenuator 200 due to vibration). Based on this absolutely tight fit and air gap-free physical foundation, the light guide 100 is positioned across the optical path channel A of the alignment sleeve 201, and is given a specific preset thickness L or a specific mismatched preset refractive index n. This actively constructs an extremely stable "optical mismatch interface" in the optical path, enabling the optical signal passing through the light guide 100 to produce a precise power attenuation of a predetermined decibel value (such as 5dB, 10dB, 15dB, etc.).

[0054] Geometric divergence attenuation mechanism based on preset thickness L: Under this mechanism, the refractive index of the light-transmitting fluid (matching paste) encapsulated inside the light guide 100 is close to that of the fiber core 501, but the thickness of the light guide 100 along the optical path channel A axis is strictly set to a relatively thick preset thickness L.

[0055] Working principle: Based on the optical characteristics of optical fiber, after the light beam leaves the fiber core 501 at the first end, it diverges outward in the transmission medium with its inherent numerical aperture (divergence angle). Since the light guide 100 has a relatively large preset thickness L, the beam's spot diameter gradually expands as it passes through this controlled thickness medium. When the beam reaches the second end of the optical fiber, the expanded spot cross-section is larger than the capturing area of ​​the receiving fiber core 501, causing edge light signals outside the core 501's range to be unable to couple into the receiving end, resulting in "light escape." By precisely controlling the filling amount of the fluid inside the light guide 100 and the axial preset thickness L of the outer film during manufacturing, the power loss rate caused by this geometric divergence can be controlled extremely precisely, achieving high-precision constant attenuation.

[0056] Interface reflection attenuation mechanism based on preset refractive index n: Under this mechanism, the light guide sheet 100 can be designed to be very thin, but the refractive index n of the light-transmitting fluid (paste) encapsulated inside it is configured to have a preset difference (refractive index mismatch) with the refractive index of the fiber core 501 (usually around 1.46).

[0057] Working principle: When an optical signal enters the optical fiber core 501 into the light guide 100 and exits from the light guide 100 into the opposite end of the optical fiber, due to the clear abrupt difference in the refractive index of the medium, the light wave will inevitably experience a certain amount of partial reflection and refraction loss at the interface of "core 501-flexible outer film-internal fluid". This refractive index mismatch loss based on the Fresnel equation is very constant and calculable. Since this scheme completely eliminates air interference, this attenuation behavior caused by the material's own refractive index difference exhibits extreme stability and is unaffected by external environment and mechanical vibration.

[0058] Furthermore, the outer diameter of the light guide 100 matches the inner diameter of the alignment sleeve 201.

[0059] The outer diameter of the light guide 100 is configured to match the inner diameter of the alignment sleeve 201 (i.e., seamless fit or micro-interference fit). In this fiber optic attenuator 200, this "outer diameter matching" is not only for physical fixation but also for creating a "miniature hydraulic constraint cavity." Since the attenuator 200 relies on the stability of the preset thickness L or density of the light guide 100, when the fiber optic connectors 500 at both ends are inserted and axial pressure is applied, the rigid inner wall of the alignment sleeve 201 forms a strict radial physical limit on the outer periphery of the light guide 100. This circumferential constraint prevents the pressurized fluid inside the light guide 100 from macroscopically overflowing or excessively dissipating radially, forcing it to maintain the preset thickness L or a stable dielectric density along the optical axis. This ensures that the attenuator 200 maintains a high degree of repeatability and consistency in its attenuation decibel value even under repeated insertion and removal or different standard insertion and removal forces (5N~15N).

[0060] Example 3

[0061] Reference Figures 3-6 This embodiment provides three specific implementation methods for the core attenuation structure (i.e., light guide plate 100) of the fiber optic attenuator 200.

[0062] It is important to note that the ultimate goal of conventional fiber optic adapter lossless connection solutions is to eliminate all physical gaps and optical barriers, allowing the optical signal to approach 0dB of lossless penetration. However, the light guide sheet 100 solution in this embodiment, under the premise of perfectly venting the air at the end face using flexible materials and ensuring absolute stability (no random fluctuations) of the physical contact surface, actively, precisely and in a controlled manner introduces irreversible optical power loss through optical means such as "spatial geometric divergence", "interface refractive index abrupt change" or "waveguide mode field mismatch".

[0063] In the first implementation: the light guide 100 has a homogeneous structure, and the refractive index of the light guide 100 is the same as or similar to the refractive index of the fiber core 501 of the docking optical fiber. The light guide 100 is configured to adjust the attenuation by adjusting its thickness along the optical path channel A axis.

[0064] In this design, the light guide 100 has an optically homogeneous structure in the light path penetration area, and the refractive index of the light guide 100 is configured to be the same as or very close to the refractive index of the fiber core 501 of the docking optical fiber (e.g., n≈1.46). Under this refractive index matching premise, the light guide 100 is configured to adjust the attenuation by adjusting the preset thickness L along the optical path channel A.

[0065] like Figure 3As shown in the optical path diagram, the optical signal is emitted from the fiber core 501 of the incident fiber and seamlessly enters the light guide 100, which is tightly attached to its end face. Since the refractive index of the medium inside the light guide 100 is highly matched with that of the fiber core 501, the optical signal experiences almost no reflection loss when crossing the physical interface of the "incident fiber-light guide 100".

[0066] However, once the light beam is freed from the waveguide constraint of the incident fiber core 501, it will naturally diverge in a conical shape along the axial direction within the light guide 100 medium of thickness L, following the inherent numerical aperture (NA) of the optical fiber. In this embodiment, the light guide 100 acts as a "controlled transmission extension medium." The larger its preset thickness L, the greater the diameter of the light spot cross-section when the beam propagates within it and finally reaches the output (receiving) fiber end face.

[0067] Combination Figure 3 Furthermore, it can be seen that when the diverged light spot reaches the output side, its projected area is significantly larger than the effective capture area of ​​the receiving fiber core 501. At this time, only the light beam located in the central region can be successfully coupled into the output fiber core 501 for continued transmission; while the light energy overflowing from the periphery of the fiber core 501 is projected onto the cladding of the output fiber (or absorbed by the inner wall of the sleeve), thus being converted into irreversible loss and attenuation.

[0068] In summary, by precisely controlling the forming process of the light guide sheet 100 during the manufacturing stage (such as strictly limiting the axial preset thickness L of the flexible packaging structure), extremely precise geometric divergence loss can be obtained by utilizing the aforementioned spatial diffusion mechanism of the light beam, achieving constant attenuation at different gradients such as 1dB to 5dB.

[0069] The second implementation: The light guide 100 is an optically homogeneous structure, but unlike the first implementation, the thickness of the light guide 100 can be made extremely thin. Its attenuation depends entirely on Fresnel reflection at the optical interface. The light guide 100 is configured to control the attenuation by the refractive index difference (Δn) between the light guide 100 and the fiber core 501.

[0070] The refractive index of the fiber core 501 of the optical fiber is set to n1 (approximately 1.46 for conventional single-mode silica fiber), and the basic refractive index of the light guide material (i.e., the matching paste inside the light guide sheet 100) is set to n2. By adjusting the polymer formula of the light guide material, a precise preset refractive index difference (i.e., Δn=|n1−n2|) is formed between it and the fiber core 501.

[0071] In this configuration, when the optical signal is emitted from the core 501 of the incident optical fiber and passes through the first physical interface of "incident side end face - light guide 100", due to the sudden change in refractive index, part of the light wave energy will inevitably be reflected back to the original optical path or scattered to the outside at this interface. Subsequently, the transmitted optical signal passes through the extremely thin light guide 100 and encounters another sudden change in refractive index when it enters the core 501 of the output optical fiber (i.e., passes through the second physical interface of "light guide 100 - output side end face"), resulting in a second Fresnel reflection loss.

[0072] Because the flexible light guide sheet 100 of this invention completely eliminates irregular air gaps, it reconstructs the originally highly volatile air interface into a seamless "fiber end face-flexible medium-fiber end face" tight contact. The two interface reflection losses caused by the preset refractive index difference are extremely stable and can be precisely calculated. This method is particularly suitable for miniature attenuators 200 with extremely stringent requirements for spatial thickness, achieving constant attenuation regardless of thickness dependence.

[0073] Third implementation method: Refer to Figures 4-6 As shown, the light guide 100 is a heterogeneous composite structure, comprising a support plate 101 with a certain mechanical rigidity, and a flexible light guide material B disposed on the support plate 101. A light guide hole 102 is formed on the support plate 101 along the axis of the optical path channel A. The flexible light guide material B fills the light guide hole 102 to form a "flexible light guide channel C," and both ends of the flexible light guide material B extend and cover the sides (butt surfaces) of the support plate 101 to ensure a zero-air-gap flexible fit with the fiber end face.

[0074] like Figure 5 and Figure 6 As shown, the original mode field width (or fiber core 501 diameter) of the incident optical fiber is set to W1, and the physical aperture or equivalent light guiding width after filling of the light guiding hole 102 in the support plate 101 is set to W2, and the relationship satisfies: W2 < W1; at the same time, the refractive index of the internal flexible light guiding channel C is set to n1, and the refractive index of the material of the outer support plate 101 is set to n2, and n1 > n2 is satisfied.

[0075] This tiered distribution of refractive index forms a microscopic "lateral refractive index barrier" on the wall of the light guide hole 102, making the light guide hole 102 filled with flexible material physically constitute an extremely small "artificial optical waveguide".

[0076] like Figure 4 and Figure 5As shown, when the optical signal is emitted from the incident optical fiber and enters the flexible light guide channel C of the light guide sheet 100: Radial constraint and mode field compression: Since the waveguide width drops sharply from W1 on the incident side to W2 in the light guide channel, and is strongly constrained by the total internal reflection of the rigid hole wall (low refractive index barrier) of the support plate 101, the optical waveguide mode is forced to shrink sharply in the radial direction, that is, the beam is "forced to be compressed" to a narrower W2 state for transmission.

[0077] When the beam, reduced to a width of W2, passes through the light guide 100 and re-enters the output-side (receiver-side) fiber core 501 with a standard width of W1, the beam cannot fully couple with the fundamental mode of the receiver fiber due to the significant geometric abrupt change in the mode field diameters (i.e., the size mismatch between W2 and W1). The large amount of mismatched optical signal energy is rapidly converted into higher-order modes or radiation modes, overflowing from the edge of the core 501 and dissipating into the cladding of the output-side fiber, thus achieving the predetermined power attenuation.

[0078] In summary, the mode field mismatch design induced by the dual effects of "geometric contraction + refractive index barrier" not only ensures that both ends of the light guide 100 can extend to cover the sides of the support plate 101 to achieve a zero-air-gap flexible fit, but also utilizes the extremely short axial space (the thickness of the support plate 101) to create high-precision attenuation of large decibels (such as 10dB, 15dB or more). This solution maintains extremely stable attenuation values ​​while greatly reducing the physical volume of the attenuator 200.

[0079] Example 4

[0080] Reference Figures 7-10 This embodiment provides an optical fiber attenuator 200, including an alignment sleeve 201 with a radially penetrating slot 202; a light guide 100 including a light guide tongue 103 extending from the outside of the alignment sleeve 201 through the slot 202 and laterally cutting off the optical path channel A, and a light guide body 104 located outside the alignment sleeve 201 and connected to the light guide tongue 103; the light guide 100 engages with the peripheral edge of the slot 202 at the junction of the light guide body 104 and the light guide tongue 103; the attenuator 200 has a receiving cavity 203 communicating with the slot 202, and the light guide body 104 is disposed in the receiving cavity 203.

[0081] Among them, the alignment sleeve 201 is made of precision ceramic sleeve.

[0082] It should be noted that this embodiment represents a structural upgrade of the "light guide 100" in the aforementioned embodiments. In this embodiment, the "light guide 100" is a single unit, composed of a light guide tongue 103 located inside the alignment sleeve 201 and a light guide body 104 located outside the sleeve. The "light guide tongue 103" is the core structure performing the optical attenuation task in the aforementioned embodiments 1-3, and its specific optical attenuation mechanism (such as based on thickness L, refractive index n, or heterogeneous waveguide structure) can be completely referred to any implementation method in embodiment 3.

[0083] Furthermore, the alignment sleeve 201 is a ceramic sleeve. The attenuator 200 housing has an internal receiving cavity 203 communicating with the slot 202, used to fix and protect the light guide 104 located outside the sleeve. Figure 9 and Figure 10 As shown, the receiving cavity 203 is also configured to provide pressure buffering and elastic return space for the light guiding material (such as flexible matching paste) when the light guide sheet 100 is squeezed by the end face of the optical fiber. When the optical fibers on both sides squeeze the light guide tongue 103 towards the center, the flexible medium inside the light guide tongue 103 is compressed, and part of the volume or pressure can be conducted and balanced to the light guide body 104 located in the outer receiving cavity 203 through the flow channel at the junction. This "energy accumulator" design can ensure that the light guide tongue 103 quickly returns to its original optical geometry after the external squeezing force is removed, thereby ensuring the repeatability and high stability of the attenuation value.

[0084] This solution uses the slot 202 of the alignment sleeve 201 as a reference to anchor the light guide tongue 103 on the central axis of the optical path, achieving extremely high positioning accuracy. By introducing the light guide tongue 103 through slotting, the "alignment" and "attenuation" functions are highly integrated in space. Furthermore, this solution supports the rapid and flexible configuration of attenuators 200 with different ranges by replacing the light guide sheet 100 with different parameters (such as thickness, refractive index, or waveguide aperture) on the same model of alignment sleeve 201, greatly improving production efficiency and product versatility.

[0085] Example 5

[0086] Reference Figures 7-10 This embodiment provides an optical fiber attenuator 200, which includes a light guide 104 with a photosensitive element 300. The photosensitive element 300 is used to capture and sense the overflow light signal that overflows from the flexible light guide channel C and is transmitted outward through the light guide sheet 100.

[0087] In this embodiment, due to effects such as "spatial geometric divergence," "interface reflection," or "mode field mismatch," some light signals inevitably overflow and cannot enter the output fiber core 501 when the light signal passes through the light guide tongue 103 (core attenuation region). In this embodiment, a photosensitive element 300 (such as a high-sensitivity photodiode PD) is provided on the light guide body 104. Since the light guide tongue 103 and the light guide body 104 are integrated, the overflow light signal originates from the light guide tongue 103, undergoes multiple total internal reflections within the light guide material, and is directionally transmitted to the light guide body 104 located outside the sleeve via the neck light guide path at the slot 202, where it is finally fully captured and sensed by the photosensitive element 300.

[0088] Furthermore, the light guide 104 is provided with a monitoring interface for exporting the electrical signal of the photosensitive element 300. The monitoring interface is configured to calculate and feed back the online attenuation value of the attenuator 200 in real time based on the intensity of the light signal captured by the photosensitive element 300. The monitoring interface is led out to the outside of the adapter through a circuit and can be connected to an external monitoring system or a handheld testing device.

[0089] The monitoring interface design completely solves the "adjustment blind zone" problem of traditional attenuators 200. Maintenance personnel can obtain the actual loss status of the link in real time through the monitoring interface without disconnecting the optical path, enabling visualized management of attenuation and alarms for abnormal fluctuations.

[0090] Furthermore, a grating with a unique reflective feature is etched or implanted within the flexible light guide channel C. The grating is used to remotely locate the line position where the attenuator 200 is located.

[0091] Within the light guide tongue 103, a pre-designed patterned grating is integrated into the central optical path of the "flexible light guide channel C," using nanoimprinting or femtosecond laser etching. Specifically, within the rigid region of the support plate 101 adjacent to the periphery of the light guide hole, corresponding to the light-incident end face of the fiber cladding projection, a pre-designed patterned grating is integrated using nanoimprinting or femtosecond laser etching. Because the support plate 101 is made of a rigid material, its physical dimensions do not change with insertion / removal pressure, thus ensuring the long-term stability of the grating period and avoiding optical signal resolution failure caused by material deformation.

[0092] In the "heterogeneous composite structure" mode of Embodiment 3, when the light beam is forcibly contracted through the light guide hole 102, some of the overflow light signal blocked by the edge of the support plate 101 (i.e., the lateral light that does not enter the light guide hole 102) will be directly coupled to the micro-nano grating on the surface of the support plate 101. The grating reflects the characteristic signal of a specific wavelength back to the input fiber core along the original path and transmits it to the remote monitoring system. By analyzing this unique "reflected iris" characteristic peak, the system can accurately locate the specific physical position of the current attenuator 200 in the complex optical network.

[0093] In summary, this embodiment upgrades the attenuator 200 from a simple energy-consuming device into an intelligent node with "identity verification" by embedding a micro-nano grating on the rigid support plate 101. It cleverly utilizes the overflow light generated in the heterogeneous structure as a signal source, achieving remote and precise positioning and digital asset management of the attenuator 200's physical location without affecting the core optical path transmission, providing a stable and reliable technical guarantee for the transparent operation and maintenance of the optical network physical layer.

[0094] Example 6

[0095] Reference Figures 7-10 This embodiment provides an attenuation method for an optical fiber attenuator 200. Utilizing the flexible conformal capability of the light guide 100, it achieves low return loss while simultaneously achieving precise attenuation through preset optical mismatch parameters. The specific steps are as follows: Step one is the sequential insertion of connectors 500 and the reset of light guide 100: First, one side connector 500 is inserted into the alignment sleeve 201 of attenuator 200. Due to the pressure of its end face, light guide 100 is pushed to the standby position inside the sleeve. Then, the other side connector 500 is inserted. This connector 500 pushes the light guide 100 back, so that the light guide 100 is finally clamped between the end faces of the two connectors 500.

[0096] Step two is the interface coating and echo suppression stage: Under the opposing pressure of the two connectors 500, the light guide sheet 100 generates microscopic elastic rheology and conformally coats the end face of the connector 500. By physically filling the interface gap and completely expelling residual air, a flexible solid light guide path with a continuous medium is constructed, thereby eliminating Fresnel reflection caused by abrupt changes in refractive index and ensuring extremely high echo suppression capability during attenuation.

[0097] Step three is the optical mismatch construction and precision attenuation stage: In the above stable solid contact path, the controlled loss of optical power is achieved by utilizing the preset specifications of the light guide sheet 100.

[0098] Spatial divergence attenuation: By utilizing the preset thickness L of the light guide sheet 100, the light beam undergoes spatial geometric divergence over a preset distance in the light guide medium, achieving a fixed decibel attenuation due to the mode field mismatch on the output side.

[0099] Refractive index mismatch attenuation: A light guide material with a preset refractive index n (or a composite structure with a support plate 101) is used to form a controlled mismatch deviation between its refractive index and the fiber core 501, and power attenuation is achieved by controlling the interface transmittance.

[0100] Step four is the spill light sampling and online monitoring stage: The spill light signal generated due to "spatial divergence" or "mode field mismatch" is captured by the light guiding part of the light guide sheet 100 and directionally transmitted to the light guide body 104 outside the sleeve. The signal intensity is sensed by the photosensitive element 300 (such as PD), and the online attenuation value of the attenuator 200 is fed back in real time by the monitoring interface, realizing uninterrupted visual monitoring.

[0101] Step five is the route identification and remote positioning stage: A grating with unique reflective characteristics, etched or implanted within the light guide channel, provides specific pattern information when probed light passes through. This information is then identified in the background to achieve precise remote positioning of the attenuator 200's physical location and to monitor changes in the fiber optic route in real time.

[0102] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A light guide for a fiber optic attenuator, comprising: The light guide sheet (100) has a total light transmittance of ≥98.5% and a haze of ≤0.2% in the communication wavelength range of 1310 nm to 1625 nm. The absolute value of the thermo-optical coefficient is ≤2.0×10. -4 / ℃, which can ensure that when the optical power fluctuation in the network is ±3dB, the deviation of its preset attenuation value is kept within ±0.1dB; The laser damage threshold is not less than 10 kW / cm 2 to support online attenuation and monitoring of high-power optical signals.

2. The light guide of the fiber optic attenuator of claim 1, wherein: The Young's modulus of the light guide sheet (100) is between 1.5 and 8.0 MPa, so that the material can cover a gap of more than 10 μm between the end faces under a standard plug force of 5 N to 15 N.

3. The light guide of a fiber optic attenuator according to claim 1 or 2, wherein: The light guide sheet (100) includes an alignment sleeve (201) disposed in the attenuator (200), and the light guide sheet (100) as claimed in any one of claims 1 to 3 is disposed on the alignment sleeve (201).

4. An optical fiber attenuator characterized by: The light guide sheet (100) is transverse to the light path channel (A) of the alignment sleeve (201) and has a predetermined thickness L or a predetermined refractive index n to construct an optical mismatch interface in the light path, so that the optical signal passing through the light guide sheet (100) produces a predetermined decibel value of power attenuation. The outer diameter of the light guide sheet (100) matches the inner diameter of the alignment sleeve (201).

5. The fiber optic attenuator of claim 4, wherein: The light guide sheet (100) is a homogeneous structure, and the refractive index of the light guide sheet (100) is the same as or similar to the refractive index of the core (501) of the optical fiber, and the light guide sheet (100) is configured to adjust the attenuation by adjusting the thickness in the axial direction of the light path channel (A).

6. The fiber optic attenuator of claim 4, wherein: The light guide sheet (100) is a homogeneous structure, and the refractive index of the light guide sheet (100) is different from the refractive index of the core (501) of the optical fiber, and the light guide sheet (100) is configured to adjust the attenuation by the difference between the refractive index of the light guide sheet (100) and the core (501).

7. The fiber optic attenuator of claim 4, wherein: The light guide sheet (100) is a heterogeneous composite structure, which includes a support plate (101) and a flexible light guide material (B) disposed on the support plate (101).

8. The fiber optic attenuator of claim 4, wherein: The support plate (101) has a light guide hole (102) on the axis of the light path channel (A), and the flexible light guide material (B) is filled in the light guide hole (102) to form a flexible light guide channel (C), and the flexible light guide material (B) extends and covers the side surface of the support plate (101). The hole wall of the light guide hole (102) forms a lateral refractive barrier between the support plate (101) and the flexible light guide material (B).

9. The fiber optic attenuator of claim 8, wherein: The lateral refractive barrier is configured to compress the light beam passing through the flexible light guide channel (C) by radially constraining the optical waveguide mode to produce physical shrinkage of the mode field diameter, thereby achieving attenuation through mode field mismatch at the exit side.

10. The optical fiber attenuator of any one of claims 5 to 9, wherein: The alignment sleeve (201) has a radially penetrating clamping groove (202); The light guide sheet (100) includes a light guide tongue (103) extending into the interior of the alignment sleeve (201) from the exterior thereof through the clamping groove (202) and transversely cutting off the light path channel (A), and a light guide body (104) located outside the alignment sleeve (201) and connected to the light guide tongue (103); The light guide sheet (100) is clamped with the groove peripheral edge of the clamping groove (202) at the junction of the light guide body (104) and the light guide tongue (103). ​ The attenuator (200) is provided with a containing cavity (203) communicated with the clamping slot (202), and the light guide body (104) is arranged in the containing cavity (203).

11. The fiber optic attenuator of claim 10, wherein: The light guide body (104) is provided with a photosensitive element (300), and the photosensitive element (300) is used for capturing and sensing the overflow light signal overflowing from the flexible light guide channel (C) and conducted outward through the light guide sheet (100).

12. The fiber optic attenuator of claim 11, wherein: The light guide body (104) is provided with a monitoring interface for guiding the electrical signal of the photosensitive element (300), and the monitoring interface is configured to calculate and feedback the online attenuation value of the attenuator (200) in real time according to the light signal intensity captured by the photosensitive element (300).

13. The fiber optic attenuator of any of claims 8, 9, 11, 12, wherein: The flexible light guide channel (C) is etched or implanted with a grating with unique reflection characteristics, and the grating is used for remote positioning of the line position where the attenuator (200) is located.

14. An attenuation method for an optical fiber attenuator, characterized by: The application further discloses a flexible light guide sheet (100) and a flexible light guide channel (C) used in the attenuator (200). Two optical fiber connectors (500) are inserted into the alignment sleeve (201) to press the end faces of the connectors (500) against the light guide sheet (100), and the elastic rheological displacement interface of the light guide sheet (100) under pressure is used to expel the air and fill the gap between the end faces. The preset thickness, the preset refractive index or the lateral refractive index barrier of the light guide sheet (100) are used to construct an optical mismatch interface in the light path, so that the power of the light signal passing through the light guide sheet (100) is attenuated. The photosensitive element (300) is used to capture the overflow light signal conducted outward through the light guide sheet (100) in real time to feedback the real-time attenuation value, and the grating implanted in the flexible light guide channel (C) is used for remote positioning.

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