Study On The Properties Of C-Lens Collimator

As optical fiber communication develops, collimators are essential elements for micro-optic packaging of isolators, circulators, interleavers, switch, WDM, and OA. They require well collimated light beam. For this, we introduced collimator. The collimator is used for collimating emanative Gaussian beam to obtain almost parallel beam with small emanative angle, or focusing parallel beam into fiber. It can improve coupling efficiency.This article has introduced C-Lens collimator which is widely used. The influence of parameters of lens on output Gaussian beam has been calculated. The differences of Gaussian beam waist and work distance between considering 8 degree'incline on the input plane of C-Lens or not are analyzed. C-Lens collimator magnifies beam waist that refers to its radius of sphere, its refractive index and the distance between pigtail and C-Lens. As 8 degree's incline is considered, the output beam from C-Lens is ellipse Gaussian beam. It gets smaller result of beam waist and work distance than that 8 degree's incline is not considered. And this result is closer to the data CASIX has given. It can design a C-Lens which it can get a beam that its diameter of waist is 1.2mm and work distance is 300mm. As tolerance is not taken into account, it can achieve the goals as the radius of sphere is 4.88mm and the length of lens is 10.95mm when the pigtail is 0.2mm far from C-Lens.The additional coupling loss is calculated, and the formulae of return loss of C-Lens collimator are given. The additional coupling loss becomes greater when off-set axis errors or tilt errors increase. The curves of attenuation and WDL of VOA are obtained when the method of calculating additional coupling loss is used.