Lorenzo Mastronardi

All-silicon carrier accumulation modulator based on a lateral MOS-capacitor

In silicon photonics, the carrier depletion scheme has been the most commonly used mechanism for demonstrating high speed electro-optic modulation. However, in terms of phase modulation efficiency, carrier accumulation based devices potentially offer almost an order of magnitude improvement over those based on carrier depletion. Previously reported accumulation modulator designs only considered vertical metal-oxide-semiconductor (MOS)-capacitors, which imposes serious restrictions on the design flexibility and integratability with other photonic components. In this work, for the first time we report experimental demonstration of an all-silicon accumulation phase modulator based on a lateral MOS-capacitor. Using a Mach-Zehnder interferometer (MZI) modulator with a 500-µm-long phase-shifter, we demonstrate high speed modulation up to 25 Gbit/s with a modulation efficiency (VπLπ) of 1.53 V-cm.

56 Gbps Si/GeSi integrated EAM

The growing demand for fast, reliable and low power interconnect systems requires the development of efficient and scalable CMOS compatible photonic devices, in particular optical modulators. In this paper, we demonstrate an innovative electro absorption modulator (EAM) developed on an 800 nm SOI platform; the device is integrated in a rib waveguide with dimensions of a 1.5 µm x 40 µm, etched on a selectively grown GeSi cavity. High speed measurements at 1566 nm show an eye diagram with dynamic ER of 5.2 dB at 56 Gbps with a power consumption of 44 fJ/bit.The growing demand for fast, reliable and low power interconnect systems requires the development of efficient and scalable CMOS compatible photonic devices, in particular optical modulators. In this paper, we demonstrate an innovative electro absorption modulator (EAM) developed on an 800 nm SOI platform; the device is integrated in a rib waveguide with dimensions of a 1.5 μm x 40 μm, etched on a selectively grown GeSi cavity. High speed measurements at 1566 nm show an eye diagram with dynamic ER of 5.2 dB at 56 Gbps with a power consumption of 44 fJ/bit.

Mid-infrared Ge-on-Si electro-absorption modulator

We present the first waveguide electro-absorption modulator in germanium-on-silicon material platform at 3.8 μm wavelength, based on free-carrier injection into a straight waveguide. The fabricated 1 mm long device has modulation depth of >35 dB at 7 V.

Raw data for "High-speed Si/GeSi hetero-structure Electro Absorption Modulator"

Data plotted in figure 2b, 6a, 6b and 11 of the paper: Mastronardi, L. et al (2017). High-speed Si/GeSi Hetero-Structure Electro Absorption Modulator. Optics Express.

Group IV compounds for integrated photonic applications

We report methods of engineering the bandgap of SiGe and Ge compounds for the fabrication of electro absorption modulators and light emitting devices. We demonstrate uniform composition, single crystal, defect free SiGe-on-insulator formation. The composition can be tuned in different positions of the chip by modifying the structural design. We also demonstrate Ge disks with strain values of 1.1 and 0.6%.