A tree configuration single-mode fiber wavelength division multiplexer (WDM) is proposed and demonstrated. This configuration is similar to tree topology single-mode star couplers which have been reported. Both theoretical analysis and experimental data show that a tree WDM can easily achieve a very high wavelength isolation over a wide wavelength range aroun 1300 nm and 1520 nm. The wavelength isolations measured in our experiment are greater than 28 dB both from 1255 nm to 1335 nm (80 nm-wide range, 41 dB at 1305 nm) and from 1490 nm to 1565 nm (75 nm-wide range). The insertion losses are 0.7 dB at 1300 nm and 1.1 dB at 1550 nm.
Xiaotian S. Yao, Xiaotian S. Yao,
"Fused Tree WDM With High Wavelength Isolation Over Wide Wavelength Range", Proc. SPIE 0722, Components for Fiber Optic Applications, (14 January 1987); doi: 10.1117/12.937641; https://doi.org/10.1117/12.937641