Silicon Photonics for Green Data Centers

Transcription

1 Silicon Photonics for Green Data Centers

2 60 Years

3 The Datacenter Energy Problem Cloud and mobile are driving data center expansion! This is impacting datacenter systems in all areas from HPCs to small corporations. Internet, Cellular, and video traffic from: Smartphones Tablets Internet-enabled everything HDTV, Video,.... All end up.. In a datacenter somewhere 3

4 What is Driving Internet Traffic Mobile and Video Traffic Explosion..Ends up in the Datacenter IEEE Datacenter Bandwidth Assessment Study 4

5 The Datacenter Energy Problem The number of mobile devices with Internet capability is forecasted to exceed the worlds popula9on by Data center are rapidly expanding and evolving with new architectures to support this demand. Networking and silicon photonics will play key roles. A single data center suppor1ng Amazon, Google, Facebook, etc. can easily consume as much power as a small city. Datacenters worldwide consume around 30 billion WaAs of electricity, the equivalent of about 30 nuclear power plants. The power required to run servers, networks, and storage may only be a frac1on of the total; Hea1ng and cooling the datacenter contributes to overall power consump1on Redundant power in the form of backup generators and baaeries adds to the power consump1on A decade ago there were ~2 datacenters in the world that consumed 10 MW of power. Today, there are dozens of datacenters, HPCs, and many warehouse- scale facili1es planned requiring MW. (Source: the 2012 OFC/NFOEC) Large HPC, search/social, and high- end datacenters may require 100,000 servers today This is forecasted to escalate to 500,000-1million servers in the next 3-4 years 5

6 6 Datacenter Sizes of Just Yesterday

7 Mega Datacenters Built Today This is the end of the building! 7

8 8 Mega Datacenters Today

9 Mega Datacenters Built Today Facebook Apple Microsoft 9

10 The Datacenter Energy Problem Electricity bills have become the most significant expense and concern for datacenter operators today. Datacenters are es1mated to consume a phenomenal 3%- 5% of the en1re electrical power in the USA and is expected to climb significantly. Gartner Group says energy costs may increase from 10% of the IT budget today to over 50% in the next few years in the USA IDC says the cost to power servers will exceed the cost of servers by next year The total power and cooling bill for servers in the USA stands at $14 billion/year If current trends persist, this bill is going to rise to $50 billion by the end of the decade New server spend is nearly flat in growth but the installed base con1nues to grow each year. Power & cooling costs have grown from $10B in 2000 worldwide to $28B in The largest data center in the world at the Lakeside Technology Center, Chicago, covers >1 million sq. O. consuming 100 MW of power. Smaller datacenters in the Top10 are larger than half dozen football fields. MicrosoO Chicago Data Center has capacity for 224,000 server blades 10!

11 Networking Energy ConsumpTon Data centers consist of 3 main components: Servers, storage and networking; Servers consume ~40%; Storage ~37% Networks consume ~23% of the total IT power consumpton Interconnects are mainly based on copper and waste enormous amounts of energy as data rates climb Compounding effects: 1W consumed at the component-level requires 3W-7W of total power consumption in the datacenter to support it. Saving 1W x 20,000 interconnections = 20KW 11

12 12 Networking Becomes a Major BoYleneck

13 13 Luxtera 4x10G Silicon photonics Chip

14 14 Luxtera 4x25G Transceiver chip

15 15 Source: Casimer DeCusatis, CTO, IBM OIDA Datacenter Conference, OFC

16 16

17 Scaling toward complex systems We re seeing a Moore s Law- like growth in system complexity Doubling 1me is around a year Filling a re1cle with photonic devices of ~500 square microns gets us to ~1.7M devices Number of components (excluding off chip couplers) 2^20 2^15 2^10 2^ Doubling every 18 months Doubling every 12 months Selected data points from references , Year

18 How does the electronics world handle monumental complexity? A fundamental innova1on in VLSI was the separa1on of design from fabrica1on Process Design Kits (PDK) Design Rule Checking (DRC) SPICE empirical extracted models And higher levels block level, chip level, rou1ng, litho simula1on, parasi1c extrac1on, design- for- manufacturing, design- for- test, PDK automated extrac1on By comparison, where are we in silicon photonics? Layout is being done by hand for the most part LVS and DRC are primi1ve at best, if they exist at all No widely accepted SPICE equivalent

19 OpSIS- IME Process IME: Ins1tute of Microelectronics, Singapore Photonics- only process, no front- end CMOS 8 inch line, 248nm lithography, 3 etch steps, 6 silicon implants, Epi- Ge growth, 2- level metal interconnects waveguides, gra1ng couplers, modulators, Ge- on- Si detectors 19

20 OpSIS- IME process wafer scale testng Wafer- scale, normal incidence opto- electronic test setup: Automated device naviga1on and op1cal alignment Measured Passive: waveguide(loss, group index), gra1ng couplers, direc1onal couplers, Y- junc1ons Ac1ve: photodetectors (dark current, BW, damage threshold, capacitance), modulators (pn- junc1on capacitance, phase- shio, loss due to doping, ring devices and traveling- wave devices) Electrical: silicon resis1vity of different layer thickness and doping level, metal and via resis1vity, transmission line characteris1cs 20

21 OpSIS- IME- 001 Run Preliminary Result summary In OpSIS- IME PDK V2 Modulators And Detectors Opsis- IME PDK V1 Induc1ve Peaking Ge PD 0.7A/W, 58GHz 0.54A/W, 20GHz Ring Modulator 28pm/V, 45GHz 11pm/V, 19GHz Traveling Wave MZ 7V Vπ, 30GHz 7V Vπ, 15.8GHz Passive Components New Y- junc1on 0.3dB IL 1.3 db IL WG Crossing 0.18dB IL Nonuniform Gra1ng Coupler 3.1dB IL 3.7dB IL 1.2um Wide Channel WG 0.4dB/cm 500nm Rib WG 2.0dB/cm 2.4dB/cm Other PDK supported devices: Edge couplers, thermal modulators, forward PIN modulators, many more 21

22 OpSIS- IME Enhanced 58 GHz photodetector Challenge of increasing bandwidth while maintaining yields and compa1bility OpSIS PDKv1 Element 25 Gb/s detector, 0.56 A/W How to improve without changing process? Gain peaking concept U1lize closely integrated BEOL to peak out RC 22

23 Ring Modulators OpSIS PDKv1 element Tunability: 10.6 pm/v Bandwidth: 18.7 GHz How to improve the tunability and bandwidth? PN junc1on- > P+/N+ junc1on Next genera1on PDK element Performance (DC) Typical Q=2.7k, FSR=7.6nm ER> 20dB Tunability=28pm/V from to 0.5V Peak Shift (pm) Bias Voltage (V) power/ dbm Wavelength/nm 0.5V 0V 0.5V 1V 1.5V 2V 3V 23

24 Ring Modulator Cont d RF performance 45GHz EO bandwidth Low dispersion, <2ps at 50GHz 2.5Vpp driving voltage to get 5dB ER, lower voltage is possible in the cost of inser1on loss EO S21 Mag (db) EO S21 Phase (Deg) Frequency (GHz)

25 Traveling- wave Mach- Zehnder modulators Basic Concept Distributed junc1on and metal capacitance into a transmission line electrode, longer device (lower voltage) is feasible at high speed The loaded transmission line should have a RF effec1ve index matching to op1cal group index OpSIS- IME- 001 PDK element: 15.8 GHz 25 Gb/s, 1Vpp 6.2dB inser1on loss 25Gb/s Tom Beahr-Johns et.al Optics Express

26 25G Data The electrooptic (EO) S21 of a typical photodetector with 2 V reverse-bias, as well as an eye pattern at 25 Gb/s. The 3 db rolloff is at 20 GHz. 1 Vpp at 25 Gb/s. 5.2 db of extinction is achieved. 5.5 db of excess loss in addition to the intrinsic device loss is seen on the modulator for a 1 bit, due to the device bias point.

27 Sub- 1V MZI Modulators

28 Sub- 1V devices a, Electroop1c (EO) S21 parameters of both arms of the traveling- wave 5 mm device. 3 db bandwidths are seen at 10 GHz. b, An eye paaern at 20 Gb/s is shown. A 0.63 Vpp differental drive is used, centered at 0 V, with 5 db excess loss for a 1 bit and a 5 db ex1nc1on ra1o achieved. c, An eye paaern at 20 Gb/s with 1 Vpp differental drive; an excess loss of 1.6 db is achieved with 5.7 db of ex1nc1on.

29 Traveling- wave MZ, cont d Device Performance 7dB inser1on loss (excluding rou1ng wg) 9.2 V small signal bias. (7 Vπ at 0V bias) 30GHz BW on both arms at 1V reverse bias low dispersion, 50Gb/s ready: es1mated 2Vpp driving voltage for 5dB ER 5 0 Top arm S21 Mag Bot arm S21 Mag Tom arm S12 Phase Bot arm S21 Phase EO21 Magnitude/dB EOS21 Phase/deg Frequency (GHz) 29

30 40G TWMZ Test data Eye-diagrams at 40Gb/s with differential-drive: (a) 0V bias and 1.6V pp drive voltage, 3.1dB extinction ratio was achieved with bias loss of 1.4dB. (b) 0.25V reverse bias and 2.5V pp drive voltage, 5.1dB extinction ratio was achieved with bias loss of 1.7dB. 30

31 31 Ver1cal coupling package 3 db /coupler

32 Integrated Design Environments Pyxis n n n n Capture and assemble hierarchical mixed-signal schematics EDA Standard callback driven property editing Advanced constructs Net busses and bundles Implicit pins For frames and function blocks Model configuration and netlisting for multiple languages 32 Mentor and Lumerical Collaboration, Mentor Graphics Corporation

33 Mentor and Lumerical Collaboration Design Capture and Layout Implementation n Pyxis Schematic captures PDK specific design and performs netlisting n Pyxis Layout performs SDL, waveguide routing 33 Mentor and Lumerical Collaboration, Mentor Graphics Corporation

34 Things on our roadmap Co- packaging of lasers Bonding of advanced electronics Schema1c design and co- simula1on Expanded library Process improvements to make beaer devices and improve yield Enhanced sta1s1cal controls and models 34

35 Acknowledgments Tom Baehr- Jones, OPSIS Co- Director Mario Paniccia, & Jus1n RaAner, Intel Gernot Pomrenke, AFOSR IME Par1ck Lo Guo- Qiang, Selin Teo Hwee Gee, Andy Lim Eu- Jin, Jason Liow Tsung- Yang, and the rest of their team Ran Ding, Yang Liu, Yi Zhang, and the other students in the UD Nanophotonics Group MaA Streshinsky, Ari Novack, and the NUS Nanophotonics Group students