ST Connectors Explained

Published: February 7, 2025

, Last updated: February 7, 2025

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ST Connectors, also known as "Straight Tip" or BFOC (Bayonet Fiber Optic Connector), were developed by AT&T in the mid-1980s as a cost-effective and space saving alternative to the larger Biconic Connector. With a bayonet-style coupling, the ST Connector offers a quick half-turn lock, making it faster to use than earlier threaded types. Initially designed for multimode fibers, enhancements by the late 1980s enabled its use with single-mode fiber as well. Despite the introduction of the SC Connector, ST Connectors remained cost-effective, especially for multimode applications.

The ST Connector features a 2.5mm ceramic ferrule with a spring-loaded mechanism, secured by a bayonet mount. This design allows for easy connection and disconnection, suitable for both long and short-distance applications like campus networks, corporate environments, and military use. However, in cramped spaces like tight patch panels, the bayonet mechanism can be less convenient.

The 2.5mm ferrule of the ST Connector is similar to SC Connectors and FC Connectors, allowing for hybrid adapter use. Its spring-loaded, half-turn bayonet lock ensures quick and secure connections, though it's not foolproof against accidental disconnections. While suitable for multimode fiber, ST Connectors are gradually being replaced by more modern options due to space constraints in newer installations.

ST Connectors are valued for their durability and reliability, making them ideal for industrial settings. Key features include:

Bayonet mount: Provides a stable connection.
Low-cost: Widely used in legacy networks due to affordability.
Durable: Built to handle frequent connections.
Compatibility: Interchangeable with other 2.5mm ferrule connectors.

Despite being an older connector type, ST Connectors were among the most popular until 2005, known for their cost-effectiveness in budget-sensitive projects. Their design involves a spring-loaded ferrule for consistent mating force and a keyed slot for alignment.

The ST Connector, referred to as "Stab n’ Twist" at Fiber Optic Center due to its mating method, was primarily used in datacom but also features in many military applications. Its 2.5mm ferrule matches well with FC and SC connectors. While largely superseded by LC and MPO connectors in modern networking, the ST remains in use where its durability and ease of use are beneficial.

Fiber Optic Center is the industry leader for recommended ST Connector materials and equipment designed specifically for ST assemblies. Integrating our manufacturing knowledge into our customers’ worldwide operations begins with the best practices and selections.

About the Author

Kathleen Skelton Kathleen Skelton, Director of Strategic Marketing, has worked in the fiber optic, cable and connector industries for over three decades. Her core competencies in fiber optics include technologies that enable the growth, integration and performance scalability of voice, data and video communications networks and services, having worked with a majority of the strategy managers in the industry during her tenure with Lightwave. Kathleen’s marketing expertise resides in business development, strategic and digital best practices and content management. Kathleen resides outside of Boston, MA with her family. Follow @KATHLEENSKELTON

Ron Schutjens Ron Schutjens joined the Fiber Optic Center, Inc. (FOC) technical team in 2023 with his extensive knowledge of the complete fiber optic assembly process and equipment in high-volume and high-variation environments. After graduating with a MSc. in applied physics, Ron started his career in fiber optics, after relocating to Florida. Having more of an affinity for hands-on engineering, he married his education with learning the processes and equipment and quickly moved up to a manufacturing engineer position at a cable assembly house. His experience includes Compulink, later Leviton, mainly serving the commercial telecommunication industry in fiber optics assemblies. During his time as manufacturing engineer, Ron has been part of many projects for product improvements and qualifications during the design and production scale up phases. At FOC, Ron offers his practical experience working directly on the production floor to service customers, embracing challenges, and offering process improvements.

About Fiber Optic Center, Inc.

Fiber Optic Center, Inc., (FOC), is an international leader in distributing fiber optic components, equipment and supplies and has been helping customers make the best cable assemblies in the world for over two decades. Several areas of specialization and expertise, in which they are the industry leader, make them the preferred choice for many of the world’s fiber professionals. In these key technology areas, FOC is "at least as technical as the manufacturer" about the products they sell. Striving to "make the business part easy," they offer outstanding and personal customer service, low or no minimum purchase order values, and from-stock delivery on industry-leading products and technology. FOC is the industry connection to the most innovative optical products, technologies and technical experts who integrate their manufacturing knowledge and vast experience into customers' worldwide operations. @FiberOpticCntr

For further information contact:

Fiber Optic Center, Inc., 23 Centre Street, New Bedford, MA 02740-6322
Toll Free in US: 800-IS-FIBER or 800-473-4237 . Direct 508-992-6464. Email: sales@focenter.com or fiberopticcenter@focenter.com

For media contact:

Kathleen Skelton, Director of Strategic Marketing, C: 617-803-3014 . E: kskelton@focenter.com

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