最後在量測上，除了觀察到光耦合進波導外，也成功量測到元件耦合進波導的效率與耦合角度，經計算後光阻光柵的波導耦合元件在TE波的耦合效率最高為3.63%；而中空形光柵的波導耦合元件在TE波的耦合效率可達16.14%，傳遞損耗為 5.1 dB/cm，耦合角度為6.5度，TM波的耦合效率為4.93%，傳遞損耗為6.0 dB/cm，耦合角度為 -7.0度，本研究所使用的製程方法，在製作上簡單方便、節省成本並可量產，未來可以應用於生醫感測元件、光檢測器、光通訊元件。 ;In this study, a laser interference lithography is used to fabricate the sub-wavelength grating as a coupling device on a glass substrate. The purpose of this research is to reduce the device size and to enhance the coupling efficiency. The coupling device was designed using the finite-difference time-domain (FDTD) method. The grating period, depth, fill factor, film thickness and different grating structure were analyzed to enhance the coupling efficiency and reduce the coupling angle. According to the simulation results, when the working wavelength, the grating period and the Ta2O5 film are 532 nm,300 nm and 100 nm, there are optimum coupling efficiency and relatively smaller coupling angle than large period.
We used dual E-beam evaporation system with ion-beam-assisted deposition system to fabricate the bottom cladding (SiO2) and the guiding layer (Ta2O5) on glass. Then laser interference lithography was used to fabricate the grating with the period of 300 nm as a guiding layer. In this part, the best process parameters was studied to deposit the film and the precise exposure time and development time was also developed to fabricate the grating with good quality. Finally, the air hole grating was proposed to enhance the coupling efficiency. According to the FDTD simulation results, the structure can improve the coupling efficiency more effectively.
After the device fabrication, the photonic properties were measured. The results show the TE wave coupling efficiency of the photoresist grating coupling device is 3.63% and the coupling angle is 2.5 degree. And the TE wave coupling efficiency of the air hole grating device is 16.14%, the coupling angle is 6.5 degree and propagation loss is 5.1 dB/cm. The TM wave coupling efficiency is 4.93%, the coupling angle is -7 degree and propagation loss is 6.0 dB/cm.
