| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程系 === 93 === Chemical etching technique is commonly used to design the tapered fiber that is applied to the optical fiber communication since it is simple, efficient, and inexpensive. However, the tapered fiber made by this technique can cause low coupling efficiency due to the mismatch between the fiber’s mode field and laser. The current study aims to propose a new technique called two steps chemical etching technique to solve the mode field mismatch problem. This new technique utilizes the change of gradient and the rotate etching process to design fiber tips with different θx and θy cone angles on the end of the optical fiber. Moreover, this new technique, through melting, can produce different radius of curvature on both x and y axes of the lens fiber with two tapers to match the laser mode filed.
By changing the experiment parameter, the researcher can control the ratio between x and y axes’ radius of curvature of the lens fiber. With the same fabricating time, the coupling efficiency of the tapered fiber in a control group was 30% while the coupling efficiency of the lens fiber with two tapers was up to 62%. The result indicated that the lens fiber with two tapers made by the two steps chemical etching technique could increase the effects of the coupling efficiency. This technique also enlarges the practicability of the chemical etching technique with respect to designing the tapered fiber used in the optical fiber communication.
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