[clug] [OT] Optical Fibre reading list & acronym list [LONG]

steve jenkin sjenkin at canb.auug.org.au
Fri Aug 23 11:07:35 UTC 2019

Thanks for AARNET for their very generous exposition last night on their new INDIGO fibre.

I know there were acronyms and topics that I needed to read more about, so created notes for anyone playing along at home that wanted to read more or play acronym decoder.

This is ridiculously long so people can scan / search for one term and ignore the rest, not a linear / sequential read.
It’s not meant to be ‘everything about cables’ or ‘everything AARNET said'



The most important and least obvious part of the talk was about ‘proper care & feeding’ of the in-line Optical Amplifiers.
They work best with a constant power signal over the full-spectrum, otherwise their gain vs frequency curve isn’t flat enough to be usable.

Consequently there's a great deal of attention paid by everyone in generating (white?) noise to fill unused channels.
The cable operator will ‘drop’ a signal source if it is 'out of spec’ and replace it with noise from an internal source to preserve the performance of the whole system.

The 36nm “Spectrum” of each fibre pair  is shared between 4 Consortium partners as 4 x 1075Ghz + guard bands.
The cable is 2 x pairs for both SYD - PER and PER - Singapore. 4 x pairs around Indonesia.

While these Telco-grade submarine systems are super-fast, “5 nine’s” availability and hence very expensive,
we’ve seen via the application of Moore’s Law the “trickle down effect” delivering these techniques into ‘’Enterprise” gear even down to commodity servers & “workstations” and maybe desktops.

In 10 years, we might be able to run 600Gbps on affordable Optical transceivers.
Just how we drive those loads, I’m not sure.
Server backplanes are stretched by 100Gbps already.


I worked for most the 1980’s for OTC doing exchange software and other services, including email.
This was on the cusp of Fibre Optics taking over - the weekly Library Bulletin was full of articles on Fibre & Optical system research.

In 1987, Telecom built it’s first fibre trunk: SYD - CBR - MEL [roughly that route, more complex than this].
That complemented ISDN or "number 7 signalling”  SS7 - digital common channel signalling. [1988 ISDN introduced]
I’ve been told they started doing inter-exchange links before then [eg. around SYD & MEL]

From 1986 - 1991, Tasman 2 was designed and built for $160M, 2 pairs at 560Mbps. [link to press release in previous email]
OTC was merged into Telstra Feb 1992. Tas-2 was their last big build.


Those 100Gbps end-end tests…. Brought to you by good Open Source.

iPerf - The ultimate speed test tool for TCP, UDP and SCTP


PFS - electrical "power feed system” 
	- or, how do you push 1-Amp DC down copper conductor for 5,000km?

Couldn’t find a good link with those  search terms.


"Dispersion-Compensation” - it’s complex… 

Tutorial: Submarine Optical Fibre and Cable: Foundation of Undersea Communication Networks
2013. PDF


Phase / Amplitude encoding of digital bit-streams onto Optical carriers
[there’s additional layers to this, including layer-1 (link) encryption]

‘Baud’ is the measure of ’symbols / second’- how fast the carrier is being modulated.

A ’symbol’ can encode multiple bits, there’s many way to do this.
a 25G-baud signal could carry 100Gbps or much higher, depending
[Yes, you’ve all seen exactly this before with dial-up modems.]

With single mode optical signals, Polarisation can be maintained, allowing independent QPSK encoding of the different polarisations.

25Gbaud x 2-bits / symbol x 2 polarisations = 100Gbps [unsure if that’s the standard - looked but search terms failed]

Channel spacing of 25 or 50Ghz is only possible if highly tuned filters can select carrier frequencies before the receiver.
To get higher bit rates, each baud has to carry more bits, because the carrier frequencies and channel spacing are a given.

The AARNET optical encoders can be configured to a maximum of 600Gbps (QAM-64?), but they’re running at 200Gbps on longer runs and 300Gbps on shorter.
They’ve a lot of expansion capacity available.

QPSK - Quadrature Phase Shift Keying, 4 phases = 2-bits per ‘baud'

QAM - Quadrature amplitude modulation

 - QAM64 used for 600Gpbs. [not obtained due to limited SNR]

QPSK etc applied to Optical systems

Optical Component Requirements for 400Gbps and 600Gbps Coherent Systems
2017 [has eye diagrams]

For example, a single wavelength system operating at 64 Gbaud and 64 QAM can achieve 600Gbps,
 with allowance for overhead,
 over distances of 80 km suitable for datacenter interconnects (DCI).  
A modest premium of 25% in the cost of the high performance components and electronics
 gives a five-fold reduction in the cost per transmitted bit. 

Complex modulation comes to optical fibre

Because the QPSK signal travels in two polarizations,
it is called either DP-QPSK (dual-polarization QPSK) or PM-QPSK (polarization-mode QPSK)
—the terms are interchangeable and both are commonly used.


ROADM - reconfigurable optical add-drop multiplexer 


OSNR  - Optical Signal to Noise Ratio
2005 paper - PDF
Photonics and Optical Communication Course

• Optical Signal to Noise Ratio (OSNR)
• Bit Error Rate
• The Eye Diagram
• Q Factor


EDFA = Ebrium Doped Fibre Amplifier
 - lasers disguised as optical fibre

Figure 3 illustrates a simplified energy diagram of Er, 
showing how amplification takes place at 1550 nm.
Two typical wavelengths to pump an EDFA are 980 or 1480 nm.

Obligatory Wikipedia Link on Optical Amplifiers
 - SOA - Semiconductor Optical Amplifier 
 - Raman amplifier


Gain and lasing in Erbium-doped fibers were first demonstrated in 1986–87 by two groups;
	one including David N. Payne, R. Mears, I.M Jauncey and L. Reekie, from the University of Southampton
	and one from AT&T Bell Laboratories, consisting of E. Desurvire, P. Becker, and J. Simpson.[

The dual-stage optical amplifier which enabled Dense Wave Division Multiplexing (DWDM,) 
was invented by Stephen B. Alexander at Ciena Corporation.


INDIGO Consortium

Sub-partners home page, INDIGO


Press Release,  APRIL 6, 2017

Indigo subsea cable made ready for use
	36Tbps cable linking Australia to Singapore launched slightly over two years from announcement.
May 30 2019
	- article is useful for list of current cable projects

Indigo subsea cables ready for use
30 May, 2019

The Indigo subsea cable system is ready to be deployed by
	 Indosat Ooredoo, 
	 Superloop's SubPartners and 
 the consortium announced.


Long distance “Optical Communications” manufacturers


CISCO & Acacia Communications

Commentary on ‘Coherent Tech’ and why CISCO wants to buy in


Cables to Asia off Western Australia were mentioned, acronym used was ’SEA-ME-WE3'

SEA-ME-WE3 or South-East Asia - Middle East - Western Europe


In December 1994, a Memorandum of Understanding was signed by 16 Parties for the development
 of the Sea-Me-We 3 project between Western Europe and Singapore.

 In November 1996, additional MOU(s) were signed to extend the system from Singapore to the Far East and to Australia.

 Finally in January 1997, the Construction and Maintenance Agreement for Sea-Me-We 3 was signed by 92 International Carriers.

 By end-2000 the entire network was completed.


Australia vs Geography - compare the ‘Ring of File Map and Pacific Optical Cables on TeleGeography’s map [link below]
You’d think Japan to US would cross ’the ring’ twice… 

Ring of Fire

Submarine Cable Map


SCCX: Important as first Optical Fibre cable from Australia to use “Optical Amplifiers” not ‘digital regenerators’ [fixed capacity]

Southern Cross Cable
commissioned in 2000
 - 320Gbps notional capacity when built
 - currently around 

Company SCCX


Other Pacific Cables

Coral Sea Cable System - part of Australian Aid budget.
	40Tbps submarine fibre optic cable, bringing next-generation connectivity to the people of Papua New Guinea and Solomon Islands.
	• A 4,700km submarine cable system linking Sydney to Port Moresby and Honiara.


TGA - Aus to NZ

Tasman-2 entered service in late 1992, 2 x pairs @ 560Mbps PDH to NZ,.
Phase 2 was NZ to US via ? (Hawaii IIRC) - collectively called PacRim East.
Phase 3 was ‘PacRim West - cut and relocated to PNG as APNG-2.

	• RFS: 2017 March
	• Cable Length: 2,288 km

15 Apr 2016
Cable Compendium: a guide to the week’s submarine and terrestrial developments

Construction work on the first section of a new submarine cable link between New Zealand and Australia, named Tasman Global Access
(TGA), has commenced, with the laying of a 3km fibre-optic cable at Ngarunui Beach in Raglan (New Zealand), newshub.co.nz writes.

 The 2,300km direct link between Raglan and Narrabeen Beach (Australia) will incorporate three fibre pairs with a current design capacity of 20Tbps;
the system is scheduled to be RFS [Ready for Service] by end-2016. 

As previously reported by TeleGeography’s Cable Compendium, the TGA consortium
 – comprising Spark New Zealand (formerly Telecom New Zealand), Telstra and Vodafone – 
awarded the TGAdeployment contract to Paris-based equipment vendor Alcatel-Lucent (now part of Nokia) in January 2015.

 The new system will provide an alternative path for trans-Tasman traffic
 – currently routed via Tasman-2 and Southern Cross Cable Network (SCCN) –
 and is expected to significantly improve New Zealand’s international connectivity options.


Steve Jenkin, IT Systems and Design 
0412 786 915 (+61 412 786 915)
PO Box 38, Kippax ACT 2615, AUSTRALIA

mailto:sjenkin at canb.auug.org.au http://members.tip.net.au/~sjenkin

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