This article delves into the essential characteristics of optical circulators, focusing on their high isolation, low insertion loss, and compatibility with Wavelength Division Multiplexing (WDM) systems. In fiber-optic communications, wavelength-division multiplexing (WDM) is a technology which multiplexes a number of optical carrier signals onto a single optical fiber by using different wavelengths (i. FBTF type WDM costs less but offers limited optical performance (~17 dB isolation). Isolating signals traveling in opposite directions is crucial to prevent spectral overlap and crosstalk. Lastly, network nodes require bidirectional.