All-optical OFDM transmitter design using AWGRs and low-bandwidth modulators

Area of Science:

• Photonics and Optical Communications
• Signal Processing

Background:

• Arrayed-Waveguide Grating Routers (AWGRs) serve dual roles in optical Orthogonal Frequency Division Multiplexing (OFDM) systems as serial-to-parallel converters and optical Fourier transform (FT) components.
• Achieving perfect subcarrier (SC) orthogonality in all-optical OFDM systems typically requires data modulator bandwidths matching the total SC bandwidth.

Purpose of the Study:

• To investigate the potential for reducing modulator bandwidth in optical OFDM systems.
• To explore the feasibility of placing modulators before an AWGR configured for FT operations.

Main Methods:

• Utilizing system simulations to analyze the impact of modulator placement on bandwidth requirements.
• Evaluating the replacement of complex (IQ) modulators with simpler phase modulators.

Main Results:

• Demonstrated significant reduction in required modulator bandwidth.
• Showcased the successful use of 7.5-GHz bandwidth modulators in a high-throughput system (4 × 10 Gsymbol/s per polarization per wavelength).

Conclusions:

• Placing modulators before an AWGR acting as an FT simplifies optical OFDM system design.
• This configuration enables the use of less bandwidth-intensive and more compact modulators without compromising system performance.