Semiellipsoid microlens fabrication method using UV proximity printing

Abstract

We present a new semiellipsoid microlens fabrication method that controls the printing gap in the UV lithography process without thermal reflow. The UV proximity printing method can precisely control the curvature radius ratio of the semiellipsoid microlens in the fabrication process. The proposed fabrication method facilitates mass production to achieve a high-yield and high-coupling semiellipsoid microlens that is suitable to be used in commercial fiber transmission systems. A semiellipsoid microlens can be tipped on a single-mode fiber end to improve power coupling efficiency from laser diodes. The semiellipsoid microlens allows increasing the fiber spot size and numerical aperture. It is very important to control the geometric parameters in the assembly procedure to increase the optical coupling efficiency between the laser diode and single-mode fiber. Wide misalignment tolerance, low loss, and low manufacturing cost could be achieved by the proposed fabrication method. The theoretical model is first developed to predict the optical coupling efficiency for various microstructure geometries of semiellipsoid microlens and assembly parameters in this study. Then, the Taguchi method is applied to obtain the optimal geometric parameters setting. The results show that optical coupling efficiency could be significantly improved by using the optimal geometric parameters setting.

Fabrication and shape analysis of refractive ellipsoidal lens controlled by surface tension

“…In [6], it was assumed that in the tangential plane and sagittal plane, the cross profile is spherical. In [5], it was assumed that the lens is semi-ellipsoidal. Here we make a more general assumption that the droplet is ellipsoidal rather than semi-ellipsoidal.…”

“…In this case, cylindrical lens or ellipsoidal lens can be used [1][2][3][4]. Ellipsoidal lens can also improve the coupling efficiency between the laser diode and single-mode fiber [5]. When imaging under oblique illumination, single spherical lens suffers from astigmatism which prevents uniform microlens array from getting large field of view.…”

Semiellipsoid microlens fabrication method using the lift-off and alignment exposure processes

“…They used a laser beam to measure the two focal lengths corresponding to the major and minor diameters by observing the image formed by a laser beam. Hung et al [9] proposed a semiellipsoid microlens fabrication method that controls the printing gap in the UV lithography process without thermal reflow. The UV proximity printing method could precisely control the semiellipsoid microlens curvature radius ratio in the fabrication process.…”

Nonparaxial anamorphic diffractive lenses

“…Refractive anamorphic lenses have attracted much attention recently and various methods of their elaboration were proposed [4][5][6][7][8][9]. Among others should be mentioned mass-transport smoothing of etched multiple-mesa structures [4], focused ion beam deposition [6], thermal reflow of patterned photoresist [8], and ink-jet printing technology [9].…”