Fiber optic couplers are available in singlemode, multimode, and polarization-maintaining types, with various coupling ratios, port configurations, and connector options to suit diverse applications.

Types of Fiber Optic Couplers

Singlemode (SM) Couplers: Designed for long-distance and high-precision applications, SM couplers are used in optical networks, test equipment, and OCT systems. They typically operate over specific wavelength ranges and can be configured as 1x2, 1x4, 1x8, or 1x16 splitters . Multimode (MM) Couplers: These couplers handle larger core fibers (e.g., 62.5/125 µm) and support broad wavelength ranges (800–1600 nm). They are available in 1x2, 2x2, 1x4, and 1x8 configurations with standard coupling ratios like 50/50 (3 dB) or 10/90 . Polarization-Maintaining (PM) Couplers: PM couplers preserve the polarization state of light, essential for interferometry and sensing applications. They are available in 1x4, 1x8, and 1x16 PLC splitter configurations . Double-Clad Couplers: Used in specialized applications such as OCT, these couplers allow efficient light transmission in fibers with multiple cladding layers .

Coupling Ratios and Port Configurations

• Y-Couplers: Equal power distribution between outputs (50/50).
• T-Couplers: Unequal power distribution (e.g., 10/90).
• Port Configurations: 1x2, 2x2, 1x4, 1x8, 1x16, depending on application requirements .

Connectors and Termination Options

Couplers can be supplied non-terminated or with standard connectors such as FC/UPC, SC, LC, or ST. Connectorized leads are available in various ruggedization levels:

• BS-type: 250 µm coated fiber for compact size
• FL-type: 900 µm buffer tube for added protection
• RP-type: 2.5 mm reinforced jacket for rugged use Optional lead lengths and factory-installed connectors can be customized based on application needs.

Operational Specifications

• Wavelength Range: Singlemode couplers often support dual-window or wideband operation; multimode couplers cover 800–1600 nm .
• Insertion Loss: Low insertion loss is standard, ensuring minimal signal degradation.
• Directivity: High directivity for bidirectional signal transmission.
• Environmental Stability: Many couplers are ruggedized and tested for temperature and mechanical stability, suitable for telecommunications, CATV, aerospace, defense, and R&D applications .

Applications

Fiber optic couplers are used in:

• Telecommunications and data networks for splitting or combining signals
• Medical imaging such as OCT
• Industrial and military systems requiring ruggedized components
• Research and development for experimental optical setups

Manufacturers and Models

• Thorlabs: Offers SM, PM, MM, and double-clad couplers, including PLC splitters and WDMs .
• Newport: Provides multimode fused fiber couplers with ruggedized housings and various coupling ratios .
• Canstar (FCI): Produces 1x2 SM couplers with fused biconical taper technology, optional connectorized leads, and multiple housing types for different ruggedization levels . These specifications allow users to select couplers based on fiber type, wavelength, coupling ratio, port count, and environmental requirements, ensuring optimal performance for their optical systems.