High-speed interconnects in data-center and campus-area networks crucially rely on efficient and technically simple transmission techniques that use intensity modulation and direct detection (IM/DD) to bridge distances of up to a few kilometers. This requires electrooptic modulators that combine low operation voltages with large modulation bandwidth and that can be operated at high symbol rates using integrated drive circuits. Here we explore the potential of silicon-organic hybrid (SOH) Mach-Zehnder modulators (MZM) for generating high-speed IM/DD signals at line rates of up to 120 Gbit/s. Using a SiGe BiCMOS signalconditioning chip, we demonstrate that intensity-modulated duobinary (IDB) signaling allows to efficiently use the electrical bandwidth, thereby enabling line rates of up to 100 Gbit/s at bit error ratios (BER) of 8.5 × 10 −5 . This is the highest data rate achieved so far using a silicon-based MZM in combination with a dedicated signal-conditioning integrated circuit (IC). We further show four-level pulse-amplitude modulation (PAM4) at lines rates of up to 120 Gbit/s (BER = 3.2 × 10 −3 ) using a high-speed arbitrary-waveform generator and a 0.5 mm long MZM. This is the highest data rate hitherto achieved with a sub-millimeter MZM on the silicon photonic platform.

Transceivers based on electro-absorption modulators are considered as a promising candidate for the next generation 400 GbE short-reach optical networks. They are capable of combining high bandwidth and low-power operation with a very compact layout, removing the need for traveling wave electrodes and dedicated 50 Ω termination. In this paper we demonstrate the first silicon-based EAM, in combination with an in-house developed SiGe BiCMOS transceiver chipset, capable of transmitting single-lane 100 Gb/s non-return-to-zero in realtime. Transmission up to 500 m of standard single mode fiber and 2 km of non-zero dispersion shifted fiber is demonstrated, assuming a forward-error coding scheme with a bit-error rate limit of 3.8×10 −3 is used. Due to the high line rate, transmission over longer fiber spans was limited by the chromatic distortion in the fiber. As a possible solution, electrical duobinary modulation is proposed as it is more resilient to this type of fiber distortion by reducing the required optical bandwidth. We show improved performance for longer fiber spans with a 100 Gb/s electrical duobinary link, resulting in real-time sub-FEC operation over more than 2 km of standard single-mode fiber without any digital signal processing. Finally, the possibility of a 100 Gb/s EAM-to-EAM link is investigated.

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Abstract-Electrical duobinary modulation is considered as a promising way to realize high capacity because of the low bandwidth requirement on the optical/electrical components and high tolerance towards chromatic dispersion. In this paper, we demonstrate a 100 Gb/s electrical duobinary transmission over 2 km standard single-mode fibre reaching a bit error rate under 7% HD-FEC threshold with the use of PRBS-7. This link is tested in real-time without any form of digital signal processing. Inhouse developed SiGe BiCMOS transmitter and receiver ICs are used to drive an electro-absorption modulated laser and decode the received signal from a PIN-photodiode. The performance of 50 Gb/s and 70 Gb/s non-return-to-zero and electrical duobinary transmission are investigated for comparison.

A BiCMOS chip-based real-time intensity modulation/direct detection spatial division multiplexing system is experimentally demonstrated for both optical interconnects. 100 Gbps/λ/core electrical duobinary (EDB) transmission over 1 km 7-core multicore fiber (MCF) is carried out, achieving KP4 forward error correction (FEC) limit (BER < 2E-4). Using optical dispersion compensation, 7 × 100 Gbps/λ/core transmission of both non-return-to-zero (NRZ) and EDB signals over 10 km MCF transmission is achieved with BER lower than 7% overhead hard-decision FEC limit (BER < 3.8E-3). The integrated low complexity transceiver IC and analog signal processing approach make such a system highly attractive for the high-speed intra-datacenter interconnects.