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`Rafik Ward
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`Finisar » Why Use LCoS in a Wavelength Selective Switch?
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`Home > LCoS technology
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`Why Use LCoS in a Wavelength Selective Switch?
`
`Posted by Rafik Ward June 12, 2009
`
`Located in the heart of Sydney, Finisar Australia is the home of Finisar’s Wavelength Selective
`Switch (WSS) product line. In this blog post, Dr. Simon Poole, one of the founders of Finisar
`Australia, outlines the interesting technology choices leading up to the development of the Finisar
`WSS and some of the thought processes and decisions made along the way.
`
`***************************************************
`
`When we first started working on Wavelength Selective Switches (WSS) back in 2003, the critical
`decision was on which technology platform should we base our WSS? At the time, there was no
`such thing as a WSS so we could start with a clean sheet of paper and look around to see what had
`been happening in related product lines. We looked firstly at what had been achieved in the
`Wavelength Blocker space, where liquid crystal technology seemed to be the ‘weapon of choice’ and
`also at optical cross-connects, where companies like Network Photonics, OMM, Xros and many
`others had pioneered the use of MEMS switching elements. A third alternative we considered, but
`rejected, were the use of planar technology (PLCs) as we could see that this was limited to degree-
`2 ROADMs.
`
`Whilst we were investigating the various existing technology options, we also came across a
`technology called Liquid Crystal on Silicon (LCoS) which was, at the time, being developed by a
`large number of companies including Intel, Philips, and Panasonic for projection television
`applications. It was our CTO, Dr. Steve Frisken, who made the intuitive leap that we could maybe
`use this as the basis for a WSS.
`
`The huge advantage of LCoS, as opposed to the other technology platforms, was that it had a large
`number of pixels (typically 2 million) and we could create the switching ‘image’ using industry-
`standard computer display drivers – indeed much of the early product development was done using
`the DVI output from a standard PC. In addition, the fact that we had so many pixels to play with
`meant that we could envisage a whole range of additional functionality that couldn’t be achieved
`with the other technologies we were considering.
`
`At this point in our thinking, we were about to make a ‘bet your company’ decision (we were, at the
`time, a very small company called Engana) so we spent much time comparing the various options
`and in drawing up tables, similar to that below, in an attempt to analyse the various options we
`had. In all the analyses we came back to the same basic conclusion, that LCoS offered more
`flexibility at a competitive cost, but had the obvious problem that it was unproven in telecom
`applications. The table below provides a comparison of potential WSS technologies in late 2003.
`
`This analysis process made it clear that the opportunities for enhancing WSS functionality through
`the use of LCoS technology were the key to unlocking the potential of future reconfigurable
`networks and so we decided to jump on a bandwagon of one and go with the LCoS technology
`option.
`
`Five years later, we are now able to offer many of these advanced functionalities through our
`WaveShaper™ Programmable Optical Processors as well as our WSS product line .
`
`We have such a plethora of capabilities that it is still sometimes unclear what will be required for
`next generation reconfigurable networks. Some of the capabilities we can offer within our LCoS
`
`http://www.finisar.com/blogs/lightspeed/why-use-lcos-in-a-wavelength-selective-switch/[6/6/2014 8:51:36 AM]
`
`1
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`THOMAS SWAN 2002
`Finisar v. Thomas Swan
`IPR2014-00465
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`

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`platform, all of which are settable per-channel ‘on the fly’ include:
`
`• Optical “Drop-and Continue” for optical broadcast networks;
`• Mixed Channel Plan – mix-and-match of 50- and 100-GHz channels;
`• Channel Bandwidth Control – e.g. for ASE noise minimization on dropped channels;
`• Channel Dispersion Control – providing adjustable 2nd (and higher) order CD compensation; and
`• Channel Shape Control – control of the channel filter shape.
`
`What other capabilities would you like to see in a programmable WSS?
`
`Please comment here or contact me at simon.poole@finisar.com.
`
`Dr. Simon Poole is the Director of New Business Ventures of Finisar Australia
`Dr. Steve Frisken is the CTO of Finisar Australia
`
` LCoS technology, Optics, WSS products | Rafik Ward |
`
` 12:23 pm
`
`5 Comments
`
`By shemale, November 17, 2010 @ 7:31 am
`
`Interesting.
`
`By guiming chen, May 21, 2013 @ 5:56 am
`
`Dear Dr. Simon Poole,
`
`Thank you to share the history why Finisar chose LCoS to make WSS, but I am not
`sure if the LCoS for WSS is same as that for projection television or not, if different,
`why, only because wavelength is different ? thanks
`
`By Simon Poole, June 6, 2013 @ 1:33 am
`
`Dear Guiming Chen
`
`Thank you for your question. As I explained in the article, our LCoS platform is
`derived from the technology developed for projection TV. As you point out, the
`difference in wavelength range does require modifications to the design of the LCoS
`cell – in particular the thickness of the Liquid Crystal layer will generally need to be
`grater to obtain the necessary performance at 1.55µm compared to the shorter
`wavelength visible range required for TV applications.
`
`Simon Poole
`
`By Lional Rajasekera, July 15, 2013 @ 12:02 am
`
`Hi Simon
`
`Congrtulations and all the best to you.
`
`Looks like you are winning all the awards.
`
`Regards
`
`Lional R
`
`By Simon Poole, July 18, 2013 @ 1:06 am
`
`Thanks, Lional
`
`The awards are really appreciated and are built on the hard work and dedication of
`the teams I’ve been fortunate enough to work with over the years.
`
`All the best
`
`Simon
`
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`Pritha Khurana: Thank you for your
`query. We have 795nm VCSELs
`currently available for atomic
`magetometer...
`
`jarrod short: Thank you for this very
`interesting post. Are any VCSELs
`commercially available for atomic
`magnetometer...
`
`Simon Poole: Thanks, Lional The
`awards are really appreciated and are
`built on the hard work and dedication of
`the...
`
`Karl Rumelhart: I think it is interesting
`to ask: as SDN becomes increasingly
`the standard for data centers, what
`are...
`
`Lional Rajasekera: Hi Simon
`Congrtulations and all the best to you.
`Looks like you are winning all the
`awards....
`
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