What Is a Fiber Coupler?
A Fiber Coupler is a passive optical device used for branching and combining optical signals based on ratios or for splitting and combining signals based on wavelengths.
Known as optical couplers, optical splitters, fiber optic splitters, fused fiber couplers, optical branching, and fiber combiners, these devices operate without a power source and are essential in various optical applications.
Fiber Couplers are used for combining multiple inputs of light or branching a single input into multiple outputs and support connections with multiple inputs and outputs over a wide range of wavelengths (approximately 400nm to 2000nm).
Applications of Fiber Couplers
- Fiber optic communication
- Monitoring of fiber optic networks
- Fiber optic sensors
- Light sources
- Optical transceivers
- Excitation of fiber lasers
- Measurement devices
- Erbium-doped fiber amplifiers (EDFA)
- Wavelength-division multiplexing (WDM) systems
- Cable television (CATV)
- Fiber-to-the-home/Passive Optical Network (FTTH/PON)
- Coarse Wavelength Division Multiplexing (CWDM) communication
- Construction of Passive Optical Networks (PON)
- Combining signals and pump light in optical amplifiers (EDFA)
Principle of Fiber Couplers
1. Branching and Merging Fiber Couplers
Fiber Couplers use a fused and elongated portion with a smaller core diameter, causing light to spread within the cladding and bind to neighboring fibers. Adjusting the length and diameter of the fused extension creates couplers with different coupling ratios. Common ratios include 50:50, 75:25, 90:10, and 99:1.
2. Wavelength Division Multiplexing (WDM) Couplers
WDM Couplers use the same structure as optical fibers and vary in transmission distance for combining or separating light with different wavelengths. Changing the diameter and length of the fused extension allows for the separation of light with different wavelengths.
Types of Fiber Couplers
1. Classification Based on the Number of Fibers
Common types include 1×2 or 2×2 couplers, as well as 1×3, 3×3, 1×4, 1×8, 1×16, 1×32, 1×64, etc.
2. Classification Based on the Type of Fiber
Types include single-mode couplers, multi-mode couplers, polarization-maintaining, polarization-independent, double-clad, and broad-bandwidth couplers. CWDM couplers are also common, as well as couplers designed for specific applications like fluorescence microscopy and semiconductor laser applications.
Additional Information on Fiber Couplers
Manufacturing of Fiber Couplers
Fiber Couplers are made by fusing and elongating optical fibers, consisting of a core and cladding. The process involves heating, fusion, elongation, and packaging, with some products manufactured through mechanical branching and coupling for higher mechanical stress resistance.