Equalization of the coupling loss of LD array modules for an optical frequency multiplexed communications system

This paper proposes a method of equalizing the coupling loss among different channels of liquid display (LD) arrays. In this method, a second lens is used to adjust the image points to the fiber positions, which then are aligned and the coupling losses among channels are equalized. In addition, the compensation for misalignments is achieved by changing the position of the second lens. This is made possible by the dependency of the angle of the output light ray on the object height. As a result, the requirements with respect to the distortions of the optical system are relaxed by half and the module-yield with coupling loss fluctuations in the range of ±0.5 dB is improved by about three times.