Multimode and single-mode fiber connectors technology

Various optical fiber connectors using a graded-index fiber have been fabricated and good performances have been obtained during field trial tests. The average connection loss of aC-type, plug-in type, andU-link connector has been found to be 0.4, 0.34, and 0.62 dB, respectively. A new field assembly (FA) type connector using a precision made ceramic capillary has also been developed. This FA type connector is fabricated for use with single-mode fibers, and has a connection loss of 0.56 and 0.52 dB at 0.85 and 1.3 μm, respectively. By using coupling experiments between laser diodes and single-mode fibers, a laser module with a coupling loss of 1.8 dB under optimum alignment conditions has been fabricated.     

Present Status of Mechanical Connectors for Optical Fiber

Trunk transmission network systems connecting exchange offices were the first transmission systems using optical fiber cables. Subscriber network systems connecting the exchange office with each subscriber including local area networks or CATV network systems are under development at present. Two main techniques are newly required to be developed for making optical fiber mechanical connectors for optical fiber subscriber network system realization. The first is to realize a new connector with a high return loss and a low connecting loss. The second is to cut the joining cost of optical fibers. The newly developed "optical contact connector" realized a high return loss of more than 25 dB and a low connecting loss of 0.15 dB average value. A newly developed "multifiber connector" which can connect many optical fibers at the same time can save time and space for joining fiber cables, and also a "plastic molding technique" can save the cost of the connector. The performance of all these connectors is the same as that of the "optical contact connector." This paper describes the present status of the technique to obtain a high return loss connector, a multifiber connector, and a plastic molded connector for the subscriber network system.     

Novel field installable optical fiber splice and connector for optical access networks

We have developed two types of field installable connection techniques. One is mechanical splicing, which is used to connect coated optical fibers without the need for stripping or cleaning procedures. The other is a field assembly connection technique, which employs a new type of field installable connector that makes it possible to realize a physical contact connection with chamfer grinding. Mechanical splicing is achieved by precisely aligning and directly connecting coated fibers with a capillary. The assembled splice is installed with 1.3-μm single-mode fibers that have an 80-μm cladding and a 125-μm coating and they exhibit good optical performance with a low average insertion loss of 0.2 dB. Connection is achieved with our developed field installable connector by using a chamfered fiber endface and the compression force of the buckled fiber. The assembled connectors achieve physical contact with the chamfered fiber endface, which provides good optical performance with a low insertion loss of 0.11 dB.     

直插式双芯光纤活动连接器的研制

介绍最新研制的直插式双芯ＳＣ型光纤连接器，概述连接器的结构、设计特点、材料特性及制造工艺，给出了各种实验结果，该连接器用于单模光纤时平均插入损耗为０．１６ｄＢ，回波损耗〉３８ｄＢ。     

Design and performance of a modular jack type Mini-MT connector forhigh-density optical duplex connection

We have developed a modular jack type Mini-MT that employs a compact two-fiber ferrule in a housing. The connector mechanism is similar to that of a conventional electric modular jack type connector. The connector also has a locking mechanism to prevent accidental disconnection and a high packaging density of 2 fibers/cm². Fabricated connectors for single-mode two-fiber ribbons exhibit a low insertion loss of 0.17 dB and a high return loss of more than 40 dB     

Design and performance of high-precision MT-type connector for1.55-μm zero-dispersion-shifted fiber-ribbon cables

We have found that, for dispersion-shifted fiber (DSF) ribbons, the accuracy with which the fiberhole is positioned in the connector ferrule must be less than 0.6 μm to realize a low average insertion loss of about 0.1 dB. By using the high-precision ferrules, we realized MT-type connectors that achieved a very low average insertion loss of 0.11 dB with a maximum of 0.37 dB. These connectors also satisfied mechanical and environmental stability requirements. We have confirmed that our high-precision MT-type connectors can be used for joining DSF ribbon     

Single-Mode Fiber Connector Using Core-Centered Ferrules

Fiber connectors using single-mode fibers have been fabricated with an average connection loss of 0.32 dB without index matching. All dimensions of the connector parts, including those of the ferrules and fibers require only low precision. A special lathe is used, in a simple operation, to eliminate the errors of the ferrule-terminated fiber assembly.     

Improved design of APC optical connectors with slanted angle of12° for dispersion shifted optical fiber

This paper describes improved design criteria for a highly stable angled physical contact (APC) connector with a slanted angle of 12° for a dispersion shifted optical fiber, which is derived from the theoretical considerations based on experiments. A shift of the vertex point of the convex ferrule endface from the optical fiber axis is minimized, so that compatibility among APC connectors can be established by using a new type of stepped-ferrule developed by the author. When rotation angle between the mating ferrules was less than 4° in a circular direction, the insertion losses for the improved APC connectors consisting of stepped-ferrules were 0.23±0.45 dB, while the insertion losses for the conventional APC connectors consisting of tapered-ferrules measured 0.39±0.89 dB. It can be confirmed that slanted angle of the convex ferrule endface is required to be 12° to obtain a backreflection of less than -60 dB for the dispersion shifted optical fiber at the wavelength of 1.550 μm     

Mass Manufacturable 180 °-Bend Single-Mode Fiber Socket Using Hole-Assisted Low Bending Loss Fiber

High-efficiency low-cost field-installable 180deg-bend single-mode fiber (SMF) sockets are promising new fiber connector components that can facilitate network element footprint reduction and allow for more comfortable connector handling in the field. We present a novel type of small-form-factor 180deg coupling SMF socket component, yielding coupling losses between two side-by-side positioned fibers as low as 0.5 dB, making use of specially designed low bending loss hole-assisted fiber. The components are prototyped in a polymer using deep proton writing and show all the potentialities for low-cost fabrication in different types of plastics.     

Optical fiber design for field mountable connectors

This paper presents a study on optical fiber and connector ferrule assembly design optimization aimed at minimizing modal interference in field-mountable single-mode fiber connectors that utilize a ferrule mounted short fiber stubs and integrated splices. A theoretical model for analyzing the modal interference is proposed and verified experimentally. It is shown that modal interference can be reduced by optimizing both the fiber design and its surrounding material     

Performance comparison of small form factor fiber optic connectors

A comparison of small form factor (SFF) fiber optic connectors is presented for LC, MT-RJ, SC-DC, and VF-45. Multimode jumper cables were tested using industry standard test procedures and bench marked against the industry standard SC Duplex connector. Initial loss data as well as stress testing was performed. Variations were found in the performance of the connectors types and between connectors of the same type from different suppliers. In some cases the connectors out performed the SC Duplex on some tests but no connectors out performed the SC Duplex on all tests with the mechanical stress tests of axial and off-axial pull being the most difficult to exceed. These connectors are rapidly developing and are at different levels of maturity but none of them tested out to be a fully mature replacement for the SC Duplex connector yet     

Tool for inspecting faults from incorrectly cleaved fiber ends and contaminated optical fiber connector end surfaces

We investigated and analyzed faults in field installable connection due to incorrectly cleaved fiber ends and manufactured physical contact (PC)-type connectors with contaminated end surfaces in optical access fiber networks. The insertion and return losses of fiber connections using incorrectly cleaved fiber ends might be at worst more than 40 dB and less than 30 dB, respectively. With PC-type connectors whose end surfaces are contaminated, the insertion and return losses might be at worst 8.7 and 27 dB, respectively. We developed an inspection tool for cleaved fiber ends and connector end surfaces as a countermeasure. The proposed tool has a simple structure and does not require focal adjustment. It can be used to inspect and clearly determine whether a fiber has been cleaved correctly and whether there is contamination or scratches on the connector end surfaces. The tool requires a slight increase of 11% in operation time compared to conventional fiber end preparation and assembly procedures. The proposed tool provides a simple and cost-effective way to inspect cleaved fiber ends and connector end surfaces and is suitable for field use.     

Very small single-mode ten-fiber connector

A small plastic molded single-mode ten-fiber connector has been developed for high-count optical subscriber cables. The connector ferrule alignment mechanism is designed with a sufficient factor of safety to allow rough handling during connection. The ferrules are precisely aligned by alignment pins and guide sleeve. The fabricated connector, which has a cross section of just 4 mm × 6 mm, exhibited an average loss of 0.4 dB and reconnection time of less than 0.5 min. Connection loss does not change after over 1000 reconnections     

浅析光纤连接器插入损耗测试

本文介绍了光纤连接器的基本结构,阐述了导致光纤连接器产生插入损耗的主要原因,对实际测试和试验中发现的问题进行了分析,给出连接器测试及试验的建议.     

Self-aligning optical-fibre connector with magnetic-alloy-clad fibres

Novel 10-fibre connectors have been developed based on a magnetic self-aligning mechanism. The magnetic-alloy-clad fibres for the connector are attracted into V-grooves by a permanent magnet. The average connection loss is 0.4 dB with index matching. The loss for each connection point remains constant within a deviation of 0.005 dB, the measurement accuracy, for disengagement/re-engagement cycles with the connector.     

High-precision moulded connector for single-mode optical fibres

High-precision moulded connectors for single-mode optical fibres have been developed using accurate electroformed cavities. The accuracy of moulded ferrules was greatly improved to less than 1 ?m by preparing a high-precision master and a strict moulding condition control. They had a low average connection loss of 0.48 dB and could be produced by a simple moulding process.     

光纤连接器制作中的端面处理技术

插入损耗和回波损耗是光纤连接器最重要的光学指标,而影响这两个光学指标的主要因素包括光纤连接器端面质量和对准光纤的横向位移、间隙及角位移等.讨论了光纤连接器插入损耗的主要因素,对横向位移产生的插入损耗进行了理论分析及实验验证,所得到的实验值与计算值基本吻合.同时对单模光纤连接器端面研磨工艺与其光学指标的关系进行了大量的实验和理论分析,研究了光纤端面质量与回波损耗的关系,优化了适合工业生产光纤连接器的端面研磨工艺.     

High-precision 2-D SM fiber connectors fabricated through deep proton writing

High-precision two-dimensional (2-D) fiber alignment modules would offer great benefits for high-density photonic interconnects at the multichip-module level, where parallel light signals have to be transferred between integrated dense 2-D emitter and detector arrays, or for massive parallel sensing applications. In telecom, the availability of highly accurate low-cost field installable 2-D fiber couplers would boost the further integration of fiber optics in future fiber-to-the-home networks. We present deep proton writing as a prototyping technology for the mastering of small-form-factor 2-D fiber connector components. The alignment components, which we present here, consist of 4 /spl times/ 8 arrays of circular conically shaped holes for single-mode fibers and feature average insertion losses of 0.062 dB and a maximum loss of 0.15 dB, when used in a fiber butt-coupling configuration.     

High-stability measuring equipment for very small variations of optical-fibre loss

Measuring equipment for a very small variation in optical-fibre loss was developed. Long-term stability within ± 0.001 dB over a 5 h period has been achieved. A small loss variation of the optical single-mode fibre connector due to temperature change was measured.     

Loss and reflectance of standard cylindrical-ferrule single-modeconnectors modified by polishing a 10° oblique endface angles

It is shown that the reflectance performance of existing, cylindrical, keyed, single-mode fiber connectors can be significantly improved by polishing 10° oblique endfaces. This results in a maximum of -60 dB to less than -70 dB reflectance. Due to the resulting air gaps and hence multiple beam interference, the average insertion loss increase compared to physical-contact-type connectors is 0.43 dB. This is in excellent agreement with the predicted value of 0.45 dB for this type of joint. In cases where insertion loss performance is not the limited factor, this straightforward modification of standard cylindrical connectors shows potential for use in bidirectional and/or analog AM transmission systems. When the additional insertion loss cannot be tolerated, design changes in endface profiles and keying features may also be required. If fiber-to-fiber endface contact can be achieved, the same excellent reflectance performance will be achieved even with the presence of a modified index layer on the endface