SILICON-ON-INSULATOR (SOI) LARGE CROSS-SECTION RIB WAVEGUIDE (LCRW) FOR FIBER-TO-THE-HOME COUPLER DEVICES

• Main Author: Aida Khairina, Abdul Rahman
• Format: Final Year Project Report
• Language: English; English
• Published: Universiti Malaysia Sarawak, (UNIMAS) 2023
• Subjects: TA Engineering (General). Civil engineering (General)
• Online Access: http://ir.unimas.my/id/eprint/43139/1/Aida%2024pgs.pdf; http://ir.unimas.my/id/eprint/43139/2/Aida%20ft.pdf; http://ir.unimas.my/id/eprint/43139/

One of the solutions to cater to increasing internet demands is to employ Fiber-to-the- Home (FTTH) access network that mainly uses Gigabit Passive Optical Network (GPON) structure. One of the optical devices used for this network is a 3dB directional coupler using Silicon-on-Insulator (SOI) Large Cross-section Rib Waveguide (LCRW). According to previous research, coupler that uses SOI LCRW can operate in single-mode propagation, has low cost, and it can offer minimal loss. This is ideal for FTTH access network standards. In this thesis, by using the optimum symmetrical and asymmetrical LCRW, the parallel LCRW and S-Bend LCRW were designed and combined to form a 3dB directional coupler. The downstream wavelengths used in the simulation were 1480 nm and 1550 nm which is FTTH compliant. The Soref’s formula were used to design LCRW to ensure single-mode propagation for the coupler. Modal field analysis through the beam propagation method (BPM) were used in the simulation by using OptiBPM 9.0 software. The LCRW with highest refractive index (w = 7 μm, H = 7 μm, d = 0.5 μm) were chosen to model the directional coupler. From the results, it was found that the symmetrical SOI LCRW for 3dB directional coupler with total length of 12741 μm with offset spacing of 0.55 μm produced the best results of the normalised output power (NOP) of ~30% at both outputs for both downstream wavelengths. The coupling ratio at output SB3 was 50.66% for 1480 nm signal and 48.98% for 1550 nm signal.