Terabit/s Superchannels: needs, challenges and beyond

Fatima GunningPhotonic Systems GroupPhotonics Centre, IPIC

Outlook

□ IPIC and Tyndall

□ Capacity crunch: is this happening?

□ Superchannels for efficient use of bandwidth

□ Challenges

□ Alternatives

This is who we are…

2003

2015

Photonics+

Micro/Nano electronics

energy

health

environment

comms

• Sustained investment by SFI over more than a decade (>€80M) has enabled build of full photonics ecosystem at Tyndall-UCC & CIT (‘atoms to systems’)

• IPIC is driving a more coherent and inclusive technical strategy combining medium/long term research and also involving industry

Origins – History of Photonics in Cork

Superchannels(SFI CDA) Gunning

Science Foundation Ireland Centres

Hybrid Integration

Monolithic Integration

Photonic Integration

Integrated team from “atoms to systems”

Advanced facilities:semiconductor growth to systems test

• Total programme value €30M• Minimum of 30% from industry• Dynamic – can add new spokes

IPIC’s industry friendly ‘Hub and Spoke’ structure

Targeted Projects• Directly aligned with company need

• Researchers working closely with company personnel, trained in company technology requirements and roadmaps

• Companies have exclusive option to IP

Platform Research• Drives leading-edge science• Training ground for PhDs • Seeds new industry projects and start-ups

Commercial Projects• Company owns IP, full commercial rates

and overheads applied

Research Commercialisation

New Manufacturing Technologies:Micro Transfer Printing

Silicon Photonic Chip(with flipchip IC)

25Gbaud InP MZM Data Modulator

10Gb/s Burst Mode Receiver

Transmission testbeds (100Gb/s and beyond)1000km of field installed fibre supplied by BT

High Speed Communications:Optoelectronics, electronics, integration, packaging, test

Smart, small, flexible, high functionality integrated devices are key to the future of the Internet.

And this is why…

Capacity crunch

5th December 2014, Sao Paulo, Brazil

2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 -

500

1,000

1,500

2,000

2,500

3,000

3,500

Year

# In

tern

et u

sers

(mill

ions

)Demand

Source: ITU_Key_2005-2014_ICT_data

Kurt Michel, Akamai - https://blogs.akamai.com/2014/07/welcome-to-the-future.html

Limited bandwidth?

att

en

uati

on

wavelength

Physical constrains

ISD

Power density

Optimising the use of bandwidth…

In general physical terms…

Amplitude, phase, and amplitude&phase modulation

Increase baud rate // time-domain shaping

Add more frequencies (e.g. WDM)

Two orthogonal polarisations

Orthogonal modes

50GHzf

100GHzf

increasingspectral

efficiency

WDM…

The need for Superchannels

50GHzf

50GHzf

freed bandwidth!

only possible with orthogonal subcarriers

reducing crosstalk

Single wavelengthchannel

Wavelength DivisionMultiplexing

Superchannels /Orthogoanal FrequencyDivision Multiplexing F

illin

g t

he o

pti

cal p

ipe

$$$

The need for flexibility

The move to flexi-grid withsuperchannels

Challenges:• Fragmentation

• Flexible routing required

• Nonlinear impairment compensation

• Continuous monitoring

• Complex digital signal processing • High-density integration &

packaging (foundry-compatible)

0

1

Pha

se (

rads

/)

0

1

2

Pha

se (

rads

/)

2π 0 0 0 2π

Time

I

Q

• All-optical BPSK OFDM superchannel• Channels spaced Δf apart• Modulated with BPSK data at Δf

• Four-wave mixing in SOA• Pump beats with subcarriers in SOA, fluctuating the carrier density• Modulates the gain and refractive index

• Idlers produced with double the frequency spacing and double the phase• Idlers stripped of modulation, since ei0 = ei2π

• Beating the two idlers at the detector will give a recovered clock at twice the original frequency

fS2Δf

BPSKSubcarriers

BPSKSuperchannel

Pump, fP

Idlers

2ΔfFrequency

OutSOA

In

Frequency

Pump, fP BPSKSubcarriers

Δfm2

Δfm1

Δf = fS2 – fS1fS1 2fS1 – fP 2fS2 – fP

fS1 + fS2 – fP

Δfm2

Δfm1

fS2fS1

0

1

Pha

se (

rads

/)

0

1

2

Pha

se (

rads

/)

π 0 0 0 π

I

Q

Time

,Δφ1

,Δφ2

,Δφ1

,Δφ2

Optical signal processing of superchannels

M. Power et al, “"Four-wave mixing for clock recovery of phase modulated optical OFDM superchannel," Opt. Express 22, 7007-7013 (2014)

Let’s not forget the power of DSP…

NONLINEAR COMPENSATION

Dis

pe

rsio

nco

mpe

nsati

on

Constellationm a p p i n g

clock recovery/estimationSoftware defined modulation

F i l t e r i n g

All with ASICS at high sampling rates: >100 million gates

Xiang Liu et al, “Digital Signal Processing Techniques Enabling Multi-Tb/s Superchannel Transmission”, IEEE SIGNAL PROCESSING MAGAZINE pp. 16-24, March 2014

Mitigation withSoftware Defined Networks

*Katsumi Emura, OECC, Plenary 2012

http://cordis.europa.eu/infowin/acts/rus/projects/ac305.htm

http://www-video.eecs.berkeley.edu/~dtan/PV99/fecs.gif

Creative HD wallpapers

Alternatives solutions to SMF…

http://www.tuhh.de/okt/Forschung/ModeBeating/ModeBeating.htm

Exploiting multi-mode…

R. G. H. van Uden et al, Nat. Photon. 8, 865–870 (2014)

detectors

lasers

passives

opticalAmplifie

rs

1mm

slotted FP laser

HC-PBGFAW

G fi

lter

photodetector

optical amplifier

[6]

[7]

[8]

[9]

…or perhaps being adventurous with HC-PBGF

And demonstrating 100Gbit/s at 2m

H. Zhang et al, "100 Gbit/s WDM transmission at 2 µm: transmission studies in both low-loss hollow core photonic bandgap fiberand solid core fiber," Opt. Express 23, 4946-4951 (2015)

Ultimately, however…

http://www.ecokids.ca/pub/eco_info/topics/renewable_energy/

Energy is and will be finite, hence

- We need energy efficient components & networks

- We need to look into efficient/passive device cooling

http://www.photonicsspectra-digital.com/photonicsspectra/may_2015?pg=18&pm=2&fs=1#pg18

• Thank You•• •

Photonic Systems Group, Tyndall National Institute, University College Cork, Ireland.http://ie.linkedin.com/in/fatimagunning/

http://research.ucc.ie/profiles/E025/fatimagunning

http://www.tyndall.ie/users/fatimagunning

Acknowledgements:H. ZhangN. KavanaghZ. LiJ. ZhaoN. YeY. ChenN. V. WheelerJ. P. WoolerJ. R. HayesS. R. SandoghchiF. PolettiM. N. PetrovichS. U. AlamR. PhelanJ. O’CarrollB. KellyL. Grüner-NielsenD. J. RichardsonB. CorbettP. GunningA. EllisB. ManningM. PowerP. TownsendK. Razeeband many others!