Variable Splitting Ratio: Precisely adjust the split ratio from 0% to 100% for maximum flexibility in optical power distribution. Low Insertion Loss: Engineered for minimal optical loss, ensuring high transmission efficiency across all split ratios. It is a crucial part of many optical experimental and measurement systems, such as interferometers, also finding widespread application in fibre optic telecommunications. Light from an input fiber is first collimated, then sent through a beam splitting optic to divide it into two. The resultant output beams are then focused back into the output fibers. The device consists of two side-polished fibers mated to induce evanescent field coupling.