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
2003
2015
• 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
• 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
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…
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
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
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
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
http://cordis.europa.eu/infowin/acts/rus/projects/ac305.htm
http://www-video.eecs.berkeley.edu/~dtan/PV99/fecs.gif
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!
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