A three-step molding softlithographic process has been developed for the construction of a sharp Y-junction structure formation in a 1x2 Y-branch plastic optical fiber (POF) coupler design. The 1x2 Y-branch POF coupler is based on a Y-junction splitter which requires that the splitting part is constructed with sharp infinitesimal junction. The softlithographic process enables a PDMS mold to be constructed which then allows mass replication of the polymer-based POF coupler. A standard master mold based on PMMA material is fabricated using CNC milling. A secondary or auxiliary-mold process step is then introduced in order to produce a sharp Y-junction structure which is then transferred to the final PDMS stamp prior to device replication. This step utilizes a free flowing, low viscosity casting-based resin, which after curing and hardening provide the auxiliary mold for PDMS mold fabrication. The result shows that a very fine and sharp Y-junction structure can be produced easily which cannot be produced via standard two step molding softlithographic process. Models for the Y-branch POF coupler produced with and without an auxiliary mold process are constructed which show that a 16% increased in optical performance with the device replicated with the auxiliary mold process.
2. Kawase, L. R., Polymer Optical Fibers, American Scientific Publisher, Valencia, CA, 2004.
3. Ziemann, O., J. Krauser, P. E. Zamzow, and W. Daum, POF Handbook: Optical Short Range Transmission System, 2nd Ed., Springer-Verlag, 2008.
4. Takezawa, Y., S. Akasaka, S. Ohara, T. Ishibashi, H. Asano, and N. Taketani, "Low excess losses in a Y-branching plastic optical waveguide formed through injection molding," Applied Optics, Vol. 33, No. 12, 2307-2312, 1994.
5. Mizuno, H., O. Sugihara, T. Kaino, N. Okamoto, and M. Ohama, "Compact Y-branch-type polymeric optical waveguide devices with large-core connectable to plastic optical fibers," Japanese Journal of Applied Physics, Vol. 44, No. 2, 8504-8506, 2005.
6. Klotzbuecher, T., T. Braune, D. Dadic, M. Sprzagala, and A. Koch, "Fabrication of optical 1 × 2 POF couplers using the laser-LIGA technique," Laser Micromachining for Optoelectronic Device Fabrication, Proc. SPIE, Vol. 4941, 121-132, 2003.
7. Ehsan, A. A., S. Shaari, and M. K. Abd-Rahman, "Plastic optical fiber coupler with high index contrast waveguide taper," Progress In Electromagnetics Research C, Vol. 20, 125-138, 2011.
8. Beltrami, D., Planar multimode waveguides and devices, PhD Thesis, Australian National University, Canberra, Australia, 1997.
9. Ehsan, A. A., S. Shaari, and M. K. Abd Rahman, "Machining of acrylic-based Y-branch plastic optical fiber coupler with suspended waveguide taper," Optical Review, Vol. 19, No. 1, 7-12, 2012.
10. Suzuki, S., T. Kitoh, Y. Inoue, Y. Yamada, Y. Hibino, K. Moriwaki, and M. Yanagisawa, "Integrated optic Y-branching waveguides with an asymmetric branching ratio," Electronics Letters, Vol. 32, No. 8, 735-736, 1996.
11. Kim, P., K. Kwon, M. C. Park, S. H. Lee, S. M. Kim, and K. Y. Suh, "Softlithography for microfluidics: A review," BioChip Journal, Vol. 2, No. 1, 1-11, 2008.