ADOPT WINTER SCHOOL Romme Alpin

January 23–26, 2014

PROGRAM

Trail Map

Mountain Facts: Vertical drop: 275 meters Longest run: 2700 meters Total slope distance: 24 km Number of slopes: 28 Snowmaking: Yes, on all the runs. Total 679 snow canons. Number of lifts: 13 (of which 3 are six-seat express lifts). Beginner ski conveyor belt : 1 Ski rentals: Express Booking via internet: http://rommealpin.com/skidhyra__1033 or at the ski rental on place.

School Organizing Committee: Lech Wosinski and Min Yan Theme: Silicon’s bright future

Welcome message:

Every second year ADOPT is organizing a winter school.

Winter School 2014 is taking place in RommeAlpin ski resort, January 23 - 26. This time the focus is on "Silicon's bright future" and we will have 14 lecturers, both internal (KTH) and external, discussing Silicon photonics and photonic-electronic convergence on Si platform. As last time, we stay in the lodge, which also contains a restaurant, bar and a conference room. We have booked 14 rooms each having 4 beds, thus the workshop can accommodate 60 people including speakers. The whole stay including ski pass (but not ski rental and drinks) is paid by the ADOPT Linné centre!

After a very mild period this winter we booked a ski whether for the time of our school. Recently we got a lot of snow and most of the slopes are well prepared.

I hope we will have an interesting school, but also great skiing and lot of fun.

Lech, lech@kth.se 2013-09-30

Practical information:

Bus transportation

• Bus from Stockholm to Romme Alpin: leaving AlbaNova (Roslagstullsbacken 35) at 2014-01-23 2:30PM, via Electrum Kista (Isafjordsgatan 22) at 3:00PM

• Bus from Romme Alpin to Stockholm: leaving 2014-01-26 5:00PM (arriving ~7:30PM), first to Kista, then to AlbaNova

PhD course (IO3000)

A PhD student is eligible for obtaining 2 third-cycle course credits for participating the winter school. The corresponding course code is IO3000. Evaluation criteria: the participant has to follow all the lectures given during the winter school, as well as to correctly answer at least 60% of questions formulated based on the lectures. Examiner: Prof. Sebastian Lourdudoss.

Program of the school Thursday, January 23 14:30 Bus leaves from Albanova 15:00 Bus leaves from Electrum, Kista 19:15 Buffet dinner 20:30 Evening program

20:30 Welcome – Lech and Min Yan (students present themselves) 20:40 Discussion: Current status of Si in optics and photonics

Friday, January 24 8:00 Morning lectures – Si photonics - General

8:00 Gunnar Björk, KTH

ADOPT – status and news 8:15 Lorenzo Pavesi, University of Trento

Silicon nanophotonics: a new twist to silicon photonics 9:15 Coffee

9:30 Lars Thylén, Photonics and Microwave Engineering, ICT School, KTH

Photonics communications: From global reach to photonic interconnect networks on multicore architecture chips: The role of low power nanophotonics in data centers

10:30 Thomas F Krauss, University of York Photonic crystal cavities

11:30 Lunch followed by free time on ski/other activities 16:30 Afternoon lectures – Light sources 16:30 Coffee 16:45 Bart Kuyken, University of Gent

Nonlinear optics in silicon wire waveguides: Towards integrated long wavelength light sources

17:45 Jan Linnros, Material Physics, ICT School, KTH

The search for a silicon light source 19:15 Buffet dinner 20:30 Evening program 20:30 Min Yan The next Si industry in optics and photonics (Round I)

Saturday, January 25 8:00 Morning lectures – Silicon integration with other materials

8:00 Sebastian Lourdudoss, Semiconductor Materials, ICT School, KTH

Heteroepitaxy and selective area heteroepitaxy of III-V compounds on silicon for silicon photonics

9:00 Coffee

9:30 Ziyang Zhang, Fraunhofer Heinrich Hertz Institute, Berlin

Polymer photonic devices and hybrid integration on silicon platform 10:30 Robert Palmer, Christian Koos, Karlsruhe Institute of Technology

Hybrid photonic integration: Enabling technology for terabit/s communications 11:30 Lunch followed by free time on ski/other activities 16:30 Afternoon lectures – CMOS integration 16:30 Coffee

16:45 Henry Radamson, Integrated Devices and Circuits, ICT School, KTH Si-based materials for photonics and electronics 17:45 Gideon Joffe, Kaiam Corporation, Newark, CA

Silicon photonics for data communications 19:15 Conference dinner 21:15 Evening program 21:15 Min Yan The next Si industry in optics and photonics (Round II) 22:00 Winner awards - Min Yan

Sunday, January 26 8:00 Morning lectures - Implementations

8:00 Min Qiu, Optics and Photonics, ICT School, KTH

Merging silicon photonics and plasmonics 8:45 Coffee 9:00 Kristinn B. Gylfason, Micro- and Nano Systems, EES School, KTH

Biosensing with silicon photonics

9:45 Laurent Vivien, Univ. Paris Sud Silicon photonics: Optical modulation and detection

10:30 Lech Wosinski, Photonics and Microwave Engineering, ICT School, KTH

Silicon- and plasmonics-based nanophotonics for telecom and interconnects 11:30 Lunch followed by free time on ski/other activities 16:30 Afternoon coffee 17:00 Bus leaves for Stockholm - approximate arrival in Stockholm: 19:30

Abstracts of the lectures

Thomas F Krauss, University of York

Photonic crystal cavities

Abstract: The ability to confine light in ultrasmall cavities remains one of the most compelling properties of photonic crystals. I will review progress in photonic crystal cavities and highlight recent developments. The key property of these cavities is their high Finesse, based on the high reflectivity achievable with photonic crystal mirrors, combined with a very small mode volume. This affords very efficient light-matter interaction, resulting in low power nonlinear effects, low power modulation and efficient light emission.

Lorenzo Pavesi, University of Trento

Silicon nanophotonics: a new twist to silicon photonics

Abstract: Silicon photonics is a technology which enables to take pace with the development of internet and the large bandwidth requests of data center and high performance computers, still keeping low the power consumption. At the same time, many other applications are emerging for silicon photonics in such a different fields such as medicine and security. In this talk, after a brief introduction of silicon photonics I will review the opportunities that are opened by applying the nanotechnology paradigm to silicon photonics. I will discuss two examples: 1. Chaos in self induced oscillations in sequence of microrings, 3. Whispering gallery resonators for biosensing applications.

Ziyang Zhang, Fraunhofer Heinrich Hertz Institute, Berlin

Polymer photonic devices and hybrid integration on silicon platform

Abstract: Low-temperature, low-cost, flexible, and tolerant fabrication technology for polymer-based photonic devices opens up a new horizon in the design of photonic integrated circuits. Low-loss polymer waveguides can be patterned for all kinds of passive functions. Silicon-based high index material can be imbedded in polymer to form heterogeneous waveguides, in order to bring down the device footprint and broaden the device functionalities. Metals can be added, wherever necessary, as DC/RF electrode, micro heaters and deflecting mirrors. Unique properties of polymers can be utilized for ultrafast electro-optic switching and power-efficient thermo-optic tuning. Sawed or locally etched 45° mirrors combined with multi-layer / multi-core structures are paving ways for 3D photonic integration for future telecom and datacom applications. This lecture is divided into two parts. The first part summarizes the established technology on the polymer / silicon platform. The second part introduces new research directions based on silicon nitride / polymer heterogeneous waveguides.

Laurent Vivien, Univ. Paris Sud

Silicon photonics: Optical modulation and detection

Abstract: Silicon is the mainstream material in the electronic industry and it is rapidly expanding its dominance into the field of photonics. Indeed, silicon photonics has been the subject of intense research activities in both industry and academia as a compelling technology paving the way for next generation of energy-efficient high-speed computing, information processing and communications

systems. The trend is to use optics in intimate proximity to the electronic circuit, which implies a high level of optoelectronic integration. Over the last decade, the field of silicon photonics has advanced at a remarkable pace. Most applicative sectors have now included silicon photonics in their roadmaps as a key technology to be deployed over short, medium or long term horizons. This evolution towards silicon-based technologies is largely based on the vision that silicon provides a mature integration platform supported by the enormous existing CMOS manufacturing infrastructure which can be used to cost-effectively produce integrated optoelectronic circuits for a wide range of applications, including telecommunications, optical interconnects, medical screening, spectroscopy, and biological and chemical sensing… This lecture will introduce the basics and recent results of silicon optical modulators and germanium photodetectors and their integrations in a common photonic/electronic platform.

Robert Palmer, Christian Koos, Karlsruhe Institute of Technology

Hybrid photonic integration: Enabling technology for terabit/s communications

Abstract: Silicon photonics offers tremendous potential for large-scale photonic-electronic integration by enabling foundry-based fabless processing and co-integration of photonic and electronic circuitry. Silicon as an optical material, however, falls short of properties that are indispensable for high-performance devices: The indirect bandgap of crystalline silicon prevents efficient light emission, and bulk silicon does not feature any second-order optical nonlinearity due to crystal symmetry, making high-speed electro-optic modulators and power-efficient phase shifters challenging. These deficiencies can be overcome by hybrid photonic integration concepts, which combine silicon photonic circuitry with other material systems that provide complementary optical properties. We will give an overview on our research in the areas of silicon-organic hybrid (SOH) integration and photonic multi-chip integration. SOH integration combines conventional silicon-on-insulator (SOI) waveguides with functional organic cladding materials and is particularly well suited for high-speed electro-optic phase modulators and power-efficient phase shifters. Photonic multi-chip integration relies on pho-tonic wire bonding as a chip-to-chip interconnect technology and enables heterogeneous photonic systems that are assembled from known-good dies of different material systems. The review of fundamental technological concepts will be complemented by the discussion of selected application demonstrations. Hybrid photonic systems are key to power-efficient transmission of terabit/s data streams.

Bart Kuyken, University of Gent

Nonlinear optics in silicon wire waveguides: Towards integrated long wavelength light sources

Abstract: Most of the research on silicon-on-insulator integrated circuits so far has been focused on applications for telecommunication. By using the large refractive index of silicon, compact complex photonic functions have been integrated on a silicon chip. However, the transparency of silicon up to 7 µm enables the use of the platform for the mid infrared wavelength region, albeit limited by the absorption in silicon oxide from 4um on. This could lead to a whole new set of integrated photonics circuits for sensing, given the distinct absorption bands of many molecules in this wavelength region. These long wavelength integrated photonic circuits would preferably need broadband or widely tunable sources to probe these absorption bands.   We propose the use of nonlinear optics in silicon wire waveguides to generate light in this wavelength range. Nonlinear interactions in just a few cm of silicon wire waveguides can be very efficient as a result of both the high nonlinear index of silicon and the high optical confinement obtained in these waveguides. We demonstrate the generation of a supercontinuum spanning from 1.53 um up to 2.55 um in a 2 cm dispersion engineered silicon nanowire waveguide by pumping the waveguide with strong picoseconds pulses at 2.12 um [1]. Furthermore we demonstrate broadband nonlinear optical

amplification in the mid infrared of up to 50 dB [2] in these silicon waveguides. By using this broadband parametric gain, a silicon based synchronously pumped optical parametric oscillator (OPO) is constructed [3]. This OPO is tunable over 70 nm around a central wavelength of 2080 nm.   Finally, we also demonstrate the use of higher order dispersion terms to get phase matching between optical signals at very different optical frequencies in silicon wire waveguides. In this way we demonstrate conversion of signals at 2.44 um to the telecommunication band with efficiencies up to +19.5 dB [4]. One particularly attractive application of such wide conversion is the possibility of converting weak signals at the mid-IR to the telecom window after which they can be detected by a high-sensitivity telecom-band optical receiver. [1] B. Kuyken et al., "Mid-infrared to telecom-band supercontinuum generation in highly nonlinear silicon-oninsulator wire waveguides", Optics Express, 192011 [2] B. Kuyken et al., "50 dB Parametric Gain in Silicon Photonic Wires", Optics Letters, 2011 [3] X. Liu & B. Kuyken et al., "Frequency conversion of mid-infrared optical signals into the telecom band using nonlinear silicon nanophotonic wires", Nat, Phot, 2012 [4] B. Kuyken et al., "Widely Tunable Silicon Mid-Infrared Optical Parametric Oscillator", optics express, 2013

Gideon Joffe, Kaiam Corporation, Newark, CA

Silicon photonics for data communications

Abstract: Silicon photonics components, fabricated on standard CMOS platforms, are now being deployed in some commercial optical communication products. While the performance of any individual component is not as good as a state-of-the-art equivalent made on alternative platforms, the maturity of the silicon industry means that costs can be very low. This talk provides an overview of key components such as electro-optic modulators, wavelength multiplexers, and tunable lasers, and also looks at some of the challenges, especially the coupling of light into the sub-micron silicon waveguides.

Lars Thylén, Photonics and Microwave Engineering, ICT School, KTH

Photonics communications: From global reach to photonic interconnect networks on multicore architecture chips: The role of low power nanophotonics in data centers

Abstract: Photonics communications is evolving from the global network to encompass ever shorter distances. In the next generation big data centers, it is essential to increase the computation performance and network efficiency while curbing the exponentially increasing electric power consumption. A significant part of this power consumption is associated with transmission or interconnects of different length scales in the data centers. The current impending introduction of photonics interconnects in cabinet backplanes will be followed by intraboard and eventually on chip connections, though at a slower pace than predicted in an optimistic article in IEEE Spectrum in 2002. For the emerging multi- and many-core architectures, core counts are expected to double every 18 months and the bandwidth required to support concurrent computation on all cores will increase by orders of magnitude. Architecture studies and analysis of power dissipation and bandwidth requirements point to integrated nanophotonics as a solution, partly because its length independent power dissipation. Thus, photonics interconnection based on nano-scale photonic integrated circuit technology and optical waveguides of different types are of prime importance and the rapid development of the photonic integration technology is showing great promise for the deployment in the next generation data centers, including reduced power consumption , small footprint and increased functionalities. Such nanophotonics technology would include diverse materials and devices using compound semiconductors, group four semiconductors, dielectric wires, micro-rings, photonic crystals, nanowires, plasmonics, metamaterials, polymers and nanostructures. But continued progress is required not least in the practical implementation.

This lecture will briefly discuss some systems and architectures issues and focus on the device technology required for future data centers.

Jan Linnros, Material Physics, ICT School, KTH

The search for a silicon light source

Abstract: In the field of “silicon photonics” there is a great need for a silicon-based light source. In particular for on-chip optical communication the demands on such a source would be tremendous, both in terms of fast switching time and brightness to allow gigabit data streaming rates. Silicon as a material, on the other hand, is characterized by an indirect bandgap and so has been deemed a non-optical material. Yet, silicon is widely used as a solar cell material and has been shown to reach among the highest efficiencies for any material. This lecture aims at shedding light on silicon light emission, what are the theoretical limitations and which routes have been explored to make it shine. This includes pure band-to-band bulk light emission, emission by defects or by specific impurities such as erbium, by manipulating the band structure, by nanostructured silicon, by growing Ge or SiGe structures or finally by epitaxial or hybrid integration of direct bandgap light emitting layers. The pro’s and con’s of different approaches will be discussed. Finally, some new applications for silicon light emission will be presented.

Sebastian Lourdudoss, Semiconductor Materials, ICT School, KTH

Heteroepitaxy and selective area heteroepitaxy of III-V compounds on silicon for silicon photonics

Abstract: An overview of the major achievements in recent years on heteroepitaxy and selective area heteroepitaxy that are relevant to silicon photonics is given. The main focus is on the materials aspects. Under heteroepitaxy, several systems based on gallium arsenide, indium phosphide, gallium antimonide and dilute III-nitrides and their related materials, all on silicon substrate, are covered and assessed with quantum dot and quantum well lasers as device examples. The potential of the emerging SnGeSi/Si system is also presented. Under selective area heteroepitaxy, germanium-seeded indium phosphide growth from silicon dioxide trenches in silicon, indium phosphide nanopyramidal template for QD growth on silicon and epitaxial lateral overgrowth of indium phosphide on silicon are exemplified as the potential routes for monolithic integration on silicon. The expected trends and anticipated advances are indicated.

Min Qiu, Optics and Photonics, ICT School, KTH

Merging silicon photonics and plasmonics

Abstract: Silicon photonics is one of the most promising candidates for large scale photonic integration, due to its potentials of being compatible with the CMOS technology. Many of silicon photonic devices have been demonstrated for the past decade, and great advances have been made. On the other hand, plasmonic devices, nanostructures with the excitation of surface plasmon polaritons (SPPs), have also attracted increasing attention in the past decade. SPPs are essentially electromagnetic waves which travel along a metal-dielectric interface, and it may provide opportunities to confine light in a subwavelength scale. Sub-micron resonators, waveguides, bends, splitters, etc., have been demonstrated by many groups. It would thus be very interesting to seek the possibility of merging silicon photonics and plasmonics, and both parties may provide endless opportunities for novel concepts and devices. In this talk, I will review some of our recent works on this topic.

Kristinn B. Gylfason, Micro- and Nano Systems, EES School, KTH

Biosensing with silicon photonics

Abstract: Biosensor technology is an increasingly important tool in pharmaceutical development, medical diagnostics, security and safety, and environmental monitoring. Silicon photonics enable the creation of very compact biosensor arrays that are well suited for integration in Lab-on-Chip systems. We review the foundations of biosensing and the specific benefits that silicon photonics bring to the field.

Henry H. Radamson, Integrated Devices and Circuits, ICT School, KTH

Si-based materials for photonics and electronics

Abstract: Si-based materials have been dominantly used in electronic devices for more than five decades. However, in recent years, more attention was attracted to Sn-alloying with Ge (for 6-8% Sn content) when different theoretical calculations presented direct bandgap property. Therefore, Ge-Sn-Si alloys were widely proposed for photonic applications. The main drive is to find a monolithic solution for advanced chip design where data processing is performed in CMOS part and the data communication in photonic components. At first, the properties of Ge material were investigated. This is due to existence of both the direct and indirect gaps (Γ- and L-band, respectively). The difference of Γ- and L positions in conduction band of Ge is only 140 meV. In this case, the Ge bandgap can be tailored by the strain engineering for direct transitions. For example, for tensile-strained Ge, the direct bandgap part shrinks faster than indirect one when the strain amount is increased. Such strained Ge material is grown in form of PIN structures for detection or emitting light. The other application for Ge-Sn-Si is for channel material in MOSFETs for high carrier mobility. There are also visions to apply such alloys in nanowire form for beyond CMOS era in future. This tutorial will present the design of Ge-Sn-Si alloys for advanced electronic/photonic devices. The challenges to synthesize Ge-Sn-Si alloys and material processing are discussed. The focus will be on strain engineering to tailor the bandgap for high performance detectors (or lasers) operating in NIR and MIR regions.

Lech Wosinski, Photonics and Microwave Engineering, ICT School, KTH

Silicon- and plasmonics-based nanophotonics for telecom and interconnects

Abstract: Silicon-based integrated photonics became a very attractive technology for guiding and manipulating of light in highly integrated structures due to the large index contrast between silicon and cladding materials allowing for very high mode confinement. Moreover, these structures can be realized by conventional planar CMOS techniques. Different passive devices based on Si nanowire waveguides have been realized using SOI technology or amorphous silicon deposition with applications in highly integrated communication systems for optical networking, bio and sensing, as well as for computer interconnects in data centers. Nevertheless for future use, especially for inter-core and intra-core computer communication, structures allowing for subwavelength light confinement based on surface plasmon waveguiding are an attractive solution. Different methods to decrease or compensate the intrinsic high losses of these structures have been proposed. I will present our work on design and experimental realization of hybrid plasmonic waveguides and devices that allow for considerable decrease of losses, still keeping sub-wavelength light confinement.