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CSIR. CSIR-CEERI. Design and Analysis of Dual-resonant Filters in Visible and Infra-red Region Based on Polymer LPWG. CSIR. CSIR-CEERI. Outline of Presentation. Abstract Structure and Principle of Long-period Waveguide Gratings (LPWGs) Based Filters Why Polymer Based LPWG !
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CSIR CSIR-CEERI Design and Analysis of Dual-resonant Filters in Visible and Infra-red Region Based on Polymer LPWG
CSIR CSIR-CEERI Outline of Presentation • Abstract • Structure and Principle of Long-period Waveguide Gratings (LPWGs) Based Filters • Why Polymer Based LPWG ! • Design and Simulation results • Dual Resonance of Polymer LPWGs • Conclusion
Abstract CSIR CSIR-CEERI Long-period waveguide gratings (LPWGs), by using a SU-8 polymer-based channel waveguide along with NOA61 optical epoxy coated upper- and lower-cladding, are designed and theoretical analyzed. Grating period of ~ 68µm is considered with optimized grating tooth-heights, so that the transmission spectra of the gratings show strong rejection bands both at visible (450 – 460 nm) and infrared (1530 – 1540 nm) wavelength regions. Phase-matching graphs are studied in order to observe the change in resonance wavelength of the grating with the variation of waveguide parameters. LPWG-based band pass filter are also designed and analyzed by considering the same set of polymer materials. Further, temperature sensitivity of these LPWGs is analyzed theoretically. These types of waveguide grating-based filters can widely be used for visible and infrared wavelength sensing applications.
CSIR CSIR-CEERI Design Structures & Principle of LPWG Filters Band Pass Filter Band Reject Filter Resonance wavelength 0 = (N0 – Nm) N0 : Effective mode index of the fundamental core-mode Nm : Effective mode indices of higher order cladding modes 0 : Resonance wavelength : Grating period of the LPWG
CSIR CSIR-CEERI Why Polymer Based LPWG ! • Inexpensive, less process intensive • Low fabrication costs • Substrate independent • Ease of tailoring physical properties • Higher Thermo-optic coefficient than SiO2, LNB • Electro-optic coefficients can be made higher • Wider Tuning Capability Polymers under consideration: • SU-8 photodefinable polymer (Microchem, Inc.) • NOA 61 Optical epoxy (Norland Products,Inc.)
CSIR CSIR-CEERI Phase Matching Graphs ncore = 1.575 nup-cl = nlow-cl = 1.55 tcore = 3.9 µm tcl = 6.7 µm
CSIR CSIR-CEERI Simulation Results
CSIR CSIR-CEERI Dual Resonance of Polymer LPWGs ncore = 1.575 nup-cl = nlow-cl = 1.55 0=454 nm (Visible region) =1534 nm (IR region)
CSIR CSIR-CEERI Effect of the Grating Tooth Height
CSIR CSIR-CEERI Transmission Spectra for LPWG Band Pass Filter ncore = 1.575 nup-cl = nlow-cl = 1.55 tcore = 3.9 µm tcl = 6.7 µm
CSIR CSIR-CEERI Temperature Effect of LPWG
CSIR CSIR-CEERI Conclusion • Long-period waveguide gratings (LPWGs), by using a SU-8 polymer-based channel waveguide along with NOA61 optical epoxy coated upper- and lower-cladding, are designed and theoretical analyzed. • Dual resonance of LPWG has achieved in order to considering Grating period of ~ 68m and resonance wavelengths lies in both visible (454 nm) and IR (1534nm) regions. • Theoretical temperature sensitivity of optimized structure is calculated for dual resonance wavelength.
CSIR CSIR-CEERI Acknowledgement We thank all Optoelectronic Devices Group members for their cooperation. We are thankful to the Director, CSIR-CEERI, Pilani for his encouragement throughout the work.
CSIR CSIR-CEERI References • Vengsarkar, A.M., Lemaire, P.J., Judkins, J.B., Bhatia, V., Erdogan, T., Sipe, J.E., “Long-period fiber gratings as band-rejection filters,” J. Lightwave Technol. 14(1), 58-65 (1996). • Tsoi, H.C., Wong, W.H., Pun, E.Y.B., “Polymeric long-period waveguide gratings,” IEEE Photon. Technol. Lett.15, 721-724(2003). • Liu, Q., Chiang, K.S., Lor, K.P., “Long period grating in polymer ridge waveguides,” Opt. Express. 13,1150–1160 (2005). • Liu, Q., Chiang, K.S., Lor, K.P., “Dual resonance in a long period waveguide grating,” AppliedPhysics B: Laser and Optics. 86,147(2007). • Pal, S., Singh, B.R., “Analysis and design of corrugated long period gratings in silica on silicon planar waveguide,” IEEE J. Lightwave Technol. 25, 2260-2267 (2007). • Pal, S., Chauhan, A., Kumar, P., Singh, M., Pradhan, N., Sharma, M.K. Singh, K., Dhanvantri, C., “Realization of corrugated long-period gratings in silica-on silicon- based channel waveguide,” IEEE Photon. Technol. Lett. 17 (2009). • Chu, Y.M., Chiang, K.S., Liu, Q., “Widely tunable optical band pass filter by use of polymer long-period waveguide gratings,” Appl. Opt.45 (12), 2755-2760 (2006). • Tang, H. Y., Wong, W. H., Pun, E. Y. B., “Long period polymer waveguide grating devices with positive temperature sensitivity,” Appl. Phys. B. 79, 95-98 (2004).
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