Experiment and prediction of ablation depth in excimer laser micro-machining of optical polymer waveguides

• Main Authors: Tamrin, K.F., Zakariyah, S.S., Hossain, K.M.A., Sheikh, N.A.
• Format: E-Article
• Language: English
• Published: Hindawi Publishing Corporation 2018
• Subjects: TJ Mechanical engineering and machinery
• Online Access: http://ir.unimas.my/id/eprint/20019/7/Tamrin%202018%20-%20Prediction%20laser%20ablation%20-%20cutted.pdf; http://ir.unimas.my/id/eprint/20019/; https://www.hindawi.com/journals/amse/

Extending the data transfer rates through dense interconnections at inter and intra-board levels is a well-established technique especially in consumer electronics. However, this comes with a payback price - more crosstalk, electromagnetic interference (EMI) and power dissipation - which must be addressed. Optical transmission, demonstrated in optical fibre, is practically immune to the aforementioned factors, and has been demonstrated as a means of solving bottleneck involving copper-based interconnection. Among the manufacturing methods, UV laser ablation using an excimer laser has been repeatedly demonstrated as a suitable technique to fabricate multimode polymer waveguides. However, the main challenge is to precisely control and predict the topology of the waveguides without the need for extensive characterisation which is both time consuming and costly. In this paper, the authors present experimental results of investigation to relate the fluence, scanning speed, number of shots and passes at varying pulse repetition rate with the depth of ablation of an acrylate-based photopolymer. The depth of ablation essentially affects total internal reflection and insertion loss and these must be kept at minimum for a successful optical interconnection on printed circuit boards. The results are then used to predict depth of ablation for this material by means of adaptive neuro-fuzzy inference system (ANFIS) modelling. The predicted results, with a correlation of 0.9993, show good agreement with the experimental values. This finding will be useful in better predictions along with resource optimisation and ultimately helps in reducing cost of polymer waveguides fabrication.