The modulator is a key component in optical communications. Several graphene-based amplitude modulators have been reported based on electro-absorption. However, graphene phase modulators (GPMs) are necessary for functions such as applying complex modulation formats or making switches or phased arrays. Here, we present a 10 Gb s–1 GPM integrated in a Mach–Zehnder interferometer configuration. This is a compact device based on a graphene-insulator–silicon capacitor, with a phase-shifter length of 300 μm and extinction ratio of 35 dB. The GPM has a modulation efficiency of 0.28 V cm at 1,550 nm. It has 5 GHz electro-optical bandwidth and operates at 10 Gb s–1 with 2 V peak-to-peak driving voltage in a push–pull configuration for binary transmission of a non-return-to-zero data stream over 50 km of single-mode fibre. This device is the key building block for graphene-based integrated photonics, enabling compact and energy-efficient hybrid graphene–silicon modulators for telecom, datacom and other applications. A 10 Gb s–1 phase modulator based on a graphene-on-silicon Mach–Zehnder interferometer (MZI) is reported. The compact device has a phase-shifter length of only 300 μm and provides modulation of light at 1,550 nm with a 35 dB extinction ratio.

Graphene-silicon phase modulators with gigahertz bandwidth

Graphene is an ideal material for optoelectronic applications. Its photonic properties give several advantages and complementarities over Si photonics. For example, graphene enables both electro-absorption and electro-refraction modulation with an electro-optical index change exceeding 10$^{-3}$. It can be used for optical add-drop multiplexing with voltage control, eliminating the current dissipation used for the thermal detuning of microresonators, and for thermoelectric-based ultrafast optical detectors that generate a voltage without transimpedance amplifiers. Here, we present our vision for grapheme-based integrated photonics. We review graphene-based transceivers and compare them with existing technologies. Strategies for improving power consumption, manufacturability and wafer-scale integration are addressed. We outline a roadmap of the technological requirements to meet the demands of the datacom and telecom markets. We show that graphene based integrated photonics could enable ultrahigh spatial bandwidth density , low power consumption for board connectivity and connectivity between data centres, access networks and metropolitan, core, regional and long-haul optical communications.

Graphene-Based Integrated Photonics For Next-Generation Datacom And Telecom

We demonstrate a 10Gb/s Graphene Phase Modulator (GPM) integrated in a Mach-Zehnder interferometer configuration. This is a compact device, with a phase-shifter length of only 300$\mu$m, and 35dB extinction ratio. The GPM has modulation efficiency of 0.28Vcm, one order of magnitude higher compared to state-of-the-art depletion p-n junction Si phase modulators. Our GPM operates with 2V peak-to-peak driving voltage in a push-pull configuration, and it has been tested in a binary transmission of a non-return-to-zero data stream over 50km single mode fibre. This device is the key building block for graphene-based integrated photonics, enabling compact and energy efficient hybrid Si-graphene modulators for telecom, datacom and other applications

Graphene Phase Modulator

Graphene is an ideal material for optoelectronic applications. Its photonic properties give several advantages and complementarities over Si photonics. For example, graphene enables both electro-absorption and electro-refraction modulation with an electro-optical index change exceeding 10−3. It can be used for optical add–drop multiplexing with voltage control, eliminating the current dissipation used for the thermal detuning of microresonators, and for thermoelectric-based ultrafast optical detectors that generate a voltage without transimpedance amplifiers. Here, we present our vision for graphene-based integrated photonics. We review graphene-based transceivers and compare them with existing technologies. Strategies for improving power consumption, manufacturability and wafer-scale integration are addressed. We outline a roadmap of the technological requirements to meet the demands of the datacom and telecom markets. We show that graphene-based integrated photonics could enable ultrahigh spatial bandwidth density, low power consumption for board connectivity and connectivity between data centres, access networks and metropolitan, core, regional and long-haul optical communications.

Graphene-based integrated photonics for next-generation datacom and telecom

Silicon photonics is widely acknowledged as a game-changing technology, driven by the needs of datacom and telecom. Silicon photonics builds on highly capital-intensive manufacturing infrastructure, and mature open-access silicon photonics platforms are translating the technology from research fabs to industrial manufacturing levels. To meet the current market demands for silicon photonics manufacturing, a variety of open-access platforms is offered by CMOS pilot lines, R&D institutes, and commercial foundries. This paper presents an overview of existing and upcoming commercial and noncommercial open-access silicon photonics technology platforms. We also discuss the diversity in these open-access platforms and their key differentiators.

https://biblio.ugent.be/publication/8606034/file/8606037.pdf

Open-Access Silicon Photonics: Current Status and Emerging Initiatives

This paper presents a 50 Gb/s per lane hybrid BiCMOS and silicon photonic integrated circuit for use in fiber optic communications. Fine pitch copper pillars are used to integrate electronics and silicon photonics. The resulting device demonstrates the generation and detection of up to 56 Gb/s NRZ optical signals over 2-km standard single-mode fiber at 1310-nm wavelength. At 40 Gb/s, the link operates error free, and at 56 Gb/s well below KR4 RS-FEC operating BER. The power dissipation of TX including CW laser is 600 mW (450-mW driver, 150-mW CW laser), RX is 150 mW, resulting in total per channel of less than 750 mW.

Hybrid Silicon Photonic Circuits and Transceiver for 50 Gb/s NRZ Transmission Over Single-Mode Fiber

Using hybrid integration of electronics and silicon photonics integrated circuits, we demonstrate the generation and detection of up to 56Gb/s NRZ optical signals over 2km standard single mode fiber at 1310nm wavelength. The link operates error free at 40Gb/s and under KR4 FEC threshold at 56Gb/s.

Hybrid silicon photonic circuits and transceiver for 56Gb/s NRZ 2.2km transmission over single mode fiber

The ever-increasing demand for high network capacities and escalating data centers have pushed the boundary from discrete transceivers toward the integration of monolithic electro-optical ICs [1]. Furthermore, complex modulation schemes such as PAM-4 have been introduced to improve the trade-off between circuit bandwidth, power consumption, data-rate and optical-link range compared to NRZ signaling. Therefore, the cost advantage of a fully integrated silicon solution will eventually push classical discrete implementations toward obsolescence.

Antonio Santipo

Papers

Hybrid Silicon Photonic Circuits and Transceiver for 50 Gb/s NRZ Transmission Over Single-Mode Fiber

Hybrid silicon photonic circuits and transceiver for 56Gb/s NRZ 2.2km transmission over single mode fiber

12.2 A 4-Channel 200Gb/s PAM-4 BiCMOS Transceiver with Silicon Photonics Front-Ends for Gigabit Ethernet Applications