Abstract
The invention provides an optical signal splitter structure with high spectrum filtering accuracy, which employs both a birefringence filter resulting in suitable phase lags for incident lights and a multi-pass design to reach the flattening of filtered spectrum and high spectrum filtering accuracy, thus to reduce the error of filtered spectrum resulted from the mismatch in length of constituted crystals and, at the same time, to reduce the number of parts used and shorten the length of the parts too.