Gadi Sarid

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

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.

Epitaxially-grown Ge/Si avalanche photodiodes for 1.3µm light detection

We designed and fabricated Ge/Si avalanche photodiodes grown on silicon substrates. The mesa-type photodiodes exhibit a responsivity at 1310nm of 0.54A/W, a breakdown voltage thermal coefficient of 0.05%/°C, a 3dBbandwidth of 10GHz. The gain-bandwidth product was measured as 153GHz. The effective k value extracted from the excess noise factor was 0.1.

Integrated silicon photonics for optical networks [Invited]

Feature Issue on Nanoscale Integrated Photonics for Optical Networks Fiber optic communication is well established today in long-haul, metro, and some data communication segments. Optical technologies continue to penetrate more into the network owing to the increase in bandwidth demands; however, they still suffer from too expensive solutions. Silicon photonics is a new technology developing integrated photonic devices and circuits based on the unique silicon material that has already revolutionized the face of our planet through the microelectronics industry. This paper reviews silicon photonics technology at Intel, showing how using the same mature, low-cost silicon CMOS technology we develop many of the building blocks required in current and future optical networks. After introducing the silicon photonics motivation for networks, we discuss the various devices--waveguides, modulators, Raman amplifiers and lasers, photodetectors, optical interconnects, and photonic crystals--from the points of view of applications, principle of operation, process development, and performance results.

Monolithic Ge/Si avalanche photodiodes

We demonstrate mesa-type and waveguide-type Ge/Si avalanche photodiodes both with high performances. The gain-bandwidth product was measured as high as 340GHz and the receiver sensitivity was −28dBm and −30.4dBm for mesa-and waveguide-type devices, respectively.

State of the art Si-based receiver solutions for short reach applications

We report on the recent progress in Ge/Si receivers which are becoming competitive in performance with their III-V counterparts. In particular, we will focus on pin and avalanche photodetector-based receiver results at 1310 nm.

Epitaxially-Grown Germanium/Silicon Avalanche Photodiodes for Near Infrared Light Detection

Avalanche Photodiodes (APDs) are widely used in fiber-optic communications as well as imaging and sensing applications where high sensitivities are needed. Traditional InP-based APD receivers typically offer a 10 dB improvement in sensitivity up to 10 Gb/s when compared to standard p-i-n based detector counterparts. As the data rates increase, however, a limited gain-bandwidth product (~100GHz) results in degraded receiver sensitivity. An increasing amount of research is now focusing on alternative multiplication materials for APDs to overcome this limitation, and one of the most promising is silicon. The difficulty in realizing a silicon-based APD device at near infrared wavelengths is that a compatible absorbing material is difficult to find. Research on germanium-on-silicon p-i-n detectors has shown acceptable responsivity at wavelengths as long as 1550 nm, and this work extends the approach to the more complicated APD structure. We are reporting here a germanium-on-silicon Separate Absorption Charge and Multiplication (SACM) APD which operates at 1310 nm, with a responsivity of 0.55A/W at unity gain with long dark current densities. The measured gain bandwidth product of this device is much higher than that of a typical III-V APD. Other device performances, like reliability, sensitivity and thermal stability, will also be discussed in this talk. This basic demonstration of a new silicon photonic device is an important step towards practical APD devices operating at 40 Gb/s, as well as for new applications which require low cost, high volume receivers with high sensitivity such as imaging and sensing.

Progress toward competitive Ge/Si photodetectors

Research and development on silicon-based optoelectronic devices is increasing as the need for integrated optical devices is becoming more apparent. One component which has seen rapid performance improvement over the last five years has been a Ge-on-Si photodetector which can operate between 850 and 1600 nm with high quantum efficiencies and bandwidths. We have reported on three types of these detectors; normal incident illuminated p-i-n detectors, waveguide p-i-n detectors, and avalanche photodetectors (APDs). The former has achieved -14.5 dBm sensitivity at 10 Gb/s and 850 nm, which is comparable to similarly commercially packaged GaAs devices. Waveguide photodetectors have achieved bandwidths of approximately 30 GHz at 1550 nm with internal quantum efficiencies of 90%. Normal incident avalanche photodetectors operating at 1310 nm have achieved a primary responsivity of 0.54 A/W with a 3-dB bandwidth of 9GHz at a gain of 17.

850 nm Germanium Photodetector Performance

Photodetectors made from silicon-germanium have been pursued for the past two decades as a way to bring near infrared detection capability into a low-cost silicon process. The raw performance of Ge on Si detectors at 850 nm has been found to be close to that of GaAs devices in optical properties, and the leakage current for these relatively large devices is nearing that needed for many applications. Further receiver data shows that the Ge detectors are comparable to commercial receivers based on GaAs detectors at 4 Gb/s with a sensitivity lower than -18 dBm and jitter performance less than 40 ps