Doron Rubin

A high-speed silicon optical modulator based on a metal–oxide–semiconductor capacitor

Silicon has long been the optimal material for electronics, but it is only relatively recently that it has been considered as a material option for photonics. One of the key limitations for using silicon as a photonic material has been the relatively low speed of silicon optical modulators compared to those fabricated from III–V semiconductor compounds and/or electro-optic materials such as lithium niobate. To date, the fastest silicon-waveguide-based optical modulator that has been demonstrated experimentally has a modulation frequency of only ∼20 MHz (refs 10, 11), although it has been predicted theoretically that a ∼1-GHz modulation frequency might be achievable in some device structures. Here we describe an approach based on a metal–oxide–semiconductor (MOS) capacitor structure embedded in a silicon waveguide that can produce high-speed optical phase modulation: we demonstrate an all-silicon optical modulator with a modulation bandwidth exceeding 1 GHz. As this technology is compatible with conventional complementary MOS (CMOS) processing, monolithic integration of the silicon modulator with advanced electronics on a single silicon substrate becomes possible.

High-speed optical modulation based on carrier depletion in a silicon waveguide

We present a high-speed and highly scalable silicon optical modulator based on the free carrier plasma dispersion effect. The fast refractive index modulation of the device is due to electric-field-induced carrier depletion in a Silicon-on-Insulator waveguide containing a reverse biased pn junction. To achieve high-speed performance, a travelling-wave design is used to allow co-propagation of electrical and optical signals along the waveguide. We demonstrate high-frequency modulator optical response with 3 dB bandwidth of ~20 GHz and data transmission up to 30 Gb/s. Such high-speed data transmission capability will enable silicon modulators to be one of the key building blocks for integrated silicon photonic chips for next generation communication networks as well as future high performance computing applications.

High speed silicon Mach-Zehnder modulator

We demonstrate a silicon modulator with an intrinsic bandwidth of 10 GHz and data transmission from 6 Gbps to 10 Gbps. Such unprecedented bandwidth performance in silicon is achieved through improvements in material quality, device design, and driver circuitry.

31 GHz Ge n-i-p waveguide photodetectors on Silicon-on-Insulator substrate.

We report on evanescently coupled Ge waveguide photodetectors that are grown on top of Si rib waveguides. A Ge waveguide detector with a width of 7.4mum and length of 50 mum demonstrated an optical bandwidth of 31.3 GHz at -2V for 1550nm. In addition, a responsivity of 0.89 A/W at 1550 nm and dark current of 169 nA were measured from this detector at -2V. A higher responsivity of 1.16 A/W was also measured from a longer Ge waveguide detector (4.4 x 100 mum2), with a corresponding bandwidth of 29.4 GHz at -2V. An open eye diagram at 40 Gb/s is also shown.

Development of CMOS-Compatible Integrated Silicon Photonics Devices

This paper surveys technical challenges involved in designing and manufacturing integrated optoelectronic devices in a high-volume complementary metal-oxide-semiconductor (CMOS) microelectronic fabrication facility. The paper begins by introducing the motivations for building these devices in silicon. We discuss the advantages and challenges of both hybrid and monolithic strategies for optoelectronic integration. We then discuss the issues involved in building the devices in a standard CMOS facility, including specific technical examples. These include low-loss waveguides (WGs) for Raman lasers, fast silicon modulators, SiGe heterostructures for infrared photodetection, silicon-oxynitride (SiON) devices on silicon-on-insulator (SOI), silicon optical bench (SiOB) technology, and waveguide tapers. We conclude with a discussion and recommendations for future work in silicon photonics

Wavelength Division Multiplexing Based Photonic Integrated Circuits on Silicon-on-Insulator Platform

We review recent advances in the development of silicon photonic integrated circuits for high-speed and high-capacity interconnect applications. We present detailed design, fabrication, and characterization of a silicon integrated chip based on wavelength division multiplexing. In such a chip, an array of eight high-speed silicon optical modulators is monolithically integrated with a silicon-based demultiplexer and a multiplexer. We demonstrate that each optical channel operates at 25 Gb/s. Our measurements suggest the integrated chip is capable of transmitting data at an aggregate rate of 200 Gb/s. This represents a key milestone on the way for fabricating terabit per second transceiver chips to meet the demand of future terascale computing.

Recent development in a high-speed silicon optical modulator based on reverse-biased pn diode in a silicon waveguide

We review the recent development of a high-speed silicon optical modulator based on electric-field-induced carrier depletion effect in a silicon-on-insulator waveguide containing a reverse-biased p–n junction. The device design, fabrication and characterization are presented. To obtain efficient optical modulation, we design a sub-micrometer size silicon waveguide phase shifter based on both semiconductor device modeling and photonic circuit modeling. By employing traveling-wave drive that allows co-propagation of electrical and optical signals along the waveguide, we demonstrate a high-frequency modulator with 3 dB optical response bandwidth of 30 GHz and data transmission up to 40 Gb s−1. Such a high-speed silicon modulator will be a key component for silicon-photonic-integrated circuits for future computing I/O applications.

Silicon Optical Modulator for High-speed Applications

We review silicon photonic technologies enabling low-cost photonic integrated circuits (PIC) for future optical interconnects. In particular, we discuss design, fabrication, and characterization of a high-speed silicon optical modulator capable of transmitting data up to 30 Gbps.

40Gb/s Ge-on-SOI waveguide photodetectors by selective Ge growth

Ge waveguide photodetectors with dimension of 7.4 μm × 50 μm and 4.4 μm × 100 μm demonstrated optical bandwidth of 31.3 GHz and 29.4 GHz, responsivity of 0.89 A/W and 1.16 A/W at 1550 nm, and 40 Gb/s open eye diagrams at -2V.

Developments in Gigascale Silicon Optical Modulators Using Free Carrier Dispersion Mechanisms

This paper describes the recent advances made in silicon optical modulators employing the free carrier dispersion effect, specifically those governed by majority carrier dynamics. The design, fabrication, and measurements for two different devices are discussed in detail. We present an MOS capacitor-based modulator delivering 10 Gbps data with an extinction ratio of ∼ 4 dB and a pn-diode-based device with high-speed transmission of 40 Gbps and bandwidth greater than 30 GHz. Device improvements for achieving higher extinction ratios, as required for certain applications, are also discussed. These devices are key components of integrated silicon photonic chips which could enable optical interconnects in future terascale processors.