Integrated High-Speed Optical SerDes over 100GBd Based on Optical Time Division Multiplexing

An on-chip optical transceiver for transmission system over 100GBd is proposed based on optical time division multiplexing (OTDM) technology, and the performances, such as the insertion loss, the inter-symbol interference (ISI) crosstalk, and the potential symbol rate, are analyzed in detail. Co-designed with the double rail driver, on-chip Mach-Zehnder interferometer switch repeatedly generates extremely narrow sampling pulses of only 12ps full width at half maximum. Based on such narrow optical sampling pulse train, a four-stage cascaded optical switch divides the 25GHz clock cycle into four recurrent 9.5ps time slots and one blank time slot of 2ps. Thus, a 100GBd optical transmission channel is realized based on 4-bit 25Gbps bit-streams at the electrical interface. The ISI extinction ratio at the worst channel is 1.9dB with 10dB depth modulator, and the insertion loss caused by the OTDM mechanism is about 16dB. Further, taking advantages of dark modulation, an OTDM system with 5-bit 25Gbps bit-streams at the electrical interface is proposed to generate a 125GBd transmission utilizing the same optical sampling pulse. The ISI performance is much better and the extinction ratio at the worst channel is enhanced to 3.99dB.