ELE Master of Science Thesis Defense by Mohammad Al Zaben - ECE

Thursday, December 18, 2025 at 12:30pm to 2:30pm

Topic: Optimization and Validation of Receiver Filter Architectures for 25 Gbps Optical Communication Systems: A Dual-Domain Approach 

Abstract:

High-speed optical communication systems rely on careful receiver filter design to preserve timing margin and sensitivity in intensity-modulation/direct-detection (IM/DD) links. This thesis studies how receiver low-pass filter architecture and bandwidth affect 25 Gb/s non-return-to-zero (NRZ) and return-to-zero (RZ) on-off keying. A dual-domain methodology is used: optical simulations are performed in ANSYS Lumerical, and complementary baseband validation is carried out in MATLAB under additive white Gaussian noise. Six fourth-order filter responses are examined—Bessel, Butterworth, Chebyshev, Gaussian, Rectangular, and Fabry-Perot—with matched noise-equivalent bandwidths. Performance is evaluated using Q-factor, bit-error rate (BER), eye-diagram metrics, and receiver sensitivity as the cutoff frequency is swept. Results show that Bessel-NRZ provides the best timing margin around 0.75–0.8×Rb, while Butterworth-RZ yields a 2–3 dB sensitivity advantage at 1.3–1.5×Rb. Strong correlation between optical and baseband results confirms when phase linearity versus amplitude selectivity should be prioritized in practical 25 Gb/s IM/DD receiver design.  

Advisor(s): Dr. Mohammad Karim, Professor, Dept. of Electrical & Computer Engineering, UMass Dartmouth 

Committee members:

• Dr. Sezer Goren, Associate Teaching Professor, Dept. of Electrical & Computer Engineering, UMass Dartmouth
• Dr. Liudong Xing, Commonwealth Professor, Dept. of Electrical & Computer Engineering, UMass Dartmouth  

Note: All ECE Graduate Students are encouraged to attend. All interested parties are invited to attend. Open to the public. 

*For further information, please contact Dr. Mohammad Karim.

Lester W. Cory Conference Room, Science & Engineering Building (SENG), Room 213A : Zoom Link: https://umassd.zoom.us/j/91596327476 Meeting ID: 915 9632 7476 Passcode: 651222
Mohammad karim
508.999.8434
mkarim@umassd.edu
https://umassd.zoom.us/j/91596327476