orte high reliability coupler design

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2022-05-20

Optical fiber coupler is an optical passive device for optical splitting and combining. With the increasing demand for modern network communication and information exchange, the global communication network has been continuously upgraded year by year, from 2G, 3G, 4G to the current 5G, in the field of civilian applications, the market potential is great.

For example, due to the loss and dispersion of light in the optical fiber communication network, it is necessary to use optical amplifiers, especially Erbium-doped fiber amplifiers (EDFA) to extend the communication distance. The fiber optic coupler is the basic and core optical component used in EDFA. It is used in a huge amount, and the automotive laser radar for autonomous driving that has emerged in recent years also has the application of fiber optic couplers. As the basic components used in EDFA and automotive lidar, once the device fails, the corresponding equipment will not work properly, so the reliability of the fiber coupler is an important research topic.

Optical fiber coupler is the secondary processing of optical fiber under high temperature melting. The most severe failure mode of a fiber optic coupler is a fiber break, where the coupler completely loses its functionality, rendering the entire device inoperable. The main component of silica optical fiber is high-purity SiO2. Theoretically speaking, the breaking strength of commonly used optical fiber can reach 20kg. cracks, resulting in a significant reduction in its strength. The growth and propagation of these microcracks can further lead to fiber breakage. In a water environment, the surface of the glass absorbs water vapor and undergoes a slow hydrolysis reaction, resulting in the breakage of the silicon-oxygen bond in the network structure - Si-O-Si-, the bridging oxygen becomes a non-bridging oxygen, and the result of the breaking of the silicon-oxygen bond makes the glass Formation of microcracks and continuous growth of microcracks. The stress action promotes the continuation of the bond-breaking reaction. Therefore, the growth and expansion speed of the fiber fracture is the result of the joint action of stress and water corrosion. In an ideal vacuum, glass does not react with water to break bonds, so there is no fatigue phenomenon. Therefore, in order to avoid fiber fatigue and breakage and prolong the service life of the fiber, it is necessary to reduce the crack damage of the fiber as much as possible, reduce the chemical corrosion of the fiber by water, reduce the stress on the fiber, and reduce the crack growth rate.

Optical Fiber Crack Growth Diagram

Combined with the production process of fiber optic couplers, we control the generation of microcracks, screen and delay the growth of microcracks from various processing links of fiber optic couplers.

Make a flow chart

The first four steps in the flow chart are the main processing process of the fiber coupler, and each step may cause large microcracks in the optical fiber due to human operation or unreasonable tool and process design. In order to ensure a minimum fiber strength, our company designed a 100% screening test according to Corning's suggestion. The purpose of the screening test is to remove the point on the entire processed length of the fiber whose intensity is lower than or equal to the screening stress, so as to ensure the mechanical reliability of the surviving fiber.

Tension Test Design Schematic

The last step - sealing, the composition of the overall sealing structure of the orte coupler is shown in the figure below. Our company has designed a two-level sealing structure, and filled the inside of the sealing structure with moisture-proof materials to further reduce the moisture entering the coupling fiber and delay the growth of micro-cracks. Compared with other ordinary one-level sealing structures, the product has a longer service life , lower risk of failure.

Among them, 1-metal tube, 2-quartz substrate, 3-moisture-proof, shock-absorbing and heat-insulating material, 4-metal sealing plate, 5-first sealant, 6-second sealant, 7-protective glue, 8-coupling optical fiber

Orte's products are designed with unique screening methods and sealing structures, making the reliability of the products a leader in the industry and winning the trust of customers.