Cost-Effective Direct-Detection All-Optical OOK-OFDM System With Analysis of Modulator Bandwidth and Driving Power

Optical orthogonal frequency-division multiplexing (OFDM) with advanced modulation format [e.g., quadrature amplitude modulation (QAM) and quadrature phase-shift keying (QPSK)] provides many transmission advantages. As the OFDM data rate is limited by the electronic digital-to-analog (DAC) and analog-to-digital (ADC) integrated circuits, an all-optical technique (i.e., all-optical OFDM) is used to construct an OFDM symbol; hence, it can provide a significant improvement in transmission capacity. In this work, we propose and demonstrate a cost-effective 275-Gb/s direct-detection all-optical OFDM system for access or data center networks. As all wavelength channels (11 wavelengths in the experiment) are produced by one laser source, only the temperature control of one master laser is enough. In addition, each wavelength channel in the all-optical OFDM signal is encoded using on-off keying (OOK) modulation format; the traditional generation and detection circuits used in the transmitter (Tx) and receiver (Rx) of the present passive optical network can still be used. We also numerically analyze the requirements of the opt-comb-MOD (modulator used to generate the optical comb source) and the data-MOD (modulator used to generate the OOK data) in the system.