A compact-size D lens collimator for fiber coupling

The paper presents a low cost and easy to fabricate compact D lens fiber optic collimator. Both the theoretical and experimental results are presented. The beam diameter and insertion loss of the lens are theoretically analyzed by using the ABCD matrix and the overlap integral methods. The experiment results show that the smallest beam diameter is found to be in the range of 380 to 400μm as the output distance varies from 10 to 30 mm. The insertion loss of the collimator is shown to be less than 0.3 dB. This number is slightly less than the value obtained by a conventional GRIN lens of similar dimensions for 10 to 30 mm output distance operated at λ= 1550 nm.