This thesis presents a method to maximize the coupling efficiency between optical fiber and edge emitting type laser diode (LD) by means of an asphirical bi-convex microlens. The proposed microlens is fabricated using an excimer laser dragging method and has four different profiles in the x- and y-axis directions. The focus spot size of the beam and coupling efficiency of the LD to optical fiber is examined both numerically and experimentally. The results suggest that with an appropriate experimental setup, the focused spot size of the elliptically diverging beam is minimized which will contribute to increase coupling efficiency of optical fiber. The feasibility of proposed approach can be used for beam pen lithography, laser scanning, laser lithography, optical fiber
telecommunication, MEMS technology, optoelectronics.

In this thesis, the coupling efficiency of the LD to optical fiber is examined both numerically and experimentally. Firstly, a model has been demonstrated for LD characteristics and beam propagation and then optimized a lens profile to achieve
diffraction limited spot size with ray tracing software Zemax. Polynomial sag height function were chosen to design biconvex microlens. Based on simulated result, the coefficients of polynomial profile function for double-convex microlens are found. The excimer laser dragging method is then used to fabricate the double-convex microlens. By this method desired surface profile of the microlens is achieved with better surface roughness. The microlens is then easily assembled with laser diode by simple optical tap without any holder or collimating tube which will reduce assembly cost. Finally using this assembly LD beam is focused into optical fiber and measure the output power.

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