Patent ID: 7171073

Claim:
A WDM device, comprising a m-fiber collimator having a first type of grin lens coupled to a filter, the m-fiber collimator receiving a light signal and propagating the light signal through the first type of grin lens and the filter, the first type of grin lens in the m-fiber collimator having a focal plane; a n-fiber collimator having a second type of grin lens, the second type of grin lens in the n-fiber collimator receiving the light signal propagating from the filter of the m-fiber collimator, the second type of grin lens in the n-fiber collimator having a focal plane; and a first glass tube placed outside of m-fiber collimator and coupling to the first type of grin lens for processing the light signal from the m-fiber collimator inside the first glass tube to the grin lens, the m-fiber collimator including a 4-fiber pigtail inside the first glass tube for processing the light signal from the 4-fiber pigtail inside of the first lass tube; wherein the focal plane in the second type of grin lens of the n-fiber collimator is shorter than the focal plane in the first type of grin lens of the m-fiber collimator for compensating the distortion caused when the light signal travels through the filter.