The 2×2 1310 & 1490 & 1550nm Three Window Singlemode FBT Coupler Splitter With Steel Tube is a high-performance optical splitting and combining device designed for stable operation across the three key telecommunication wavelength windows: 1310 nm (O-band), 1490 nm (E-band), and 1550 nm (C-band). Manufactured using advanced Fused Biconical Taper (FBT) technology, this 2×2 splitter ensures low insertion loss, accurate coupling ratios, excellent wavelength stability, and reliable bidirectional optical performance across all three wavelength bands.