A question for those who understand filters, what's the market for 50 gig versus 100 and 200?
It's all about channel spacing. As channel counts rise in DWDM systems, it will be crucial to decrease the effective channel spacing in order to facilitate more channels in the same frequency bands. 50GHz channel spacing would be important to JDSU to get efficient high channel count filters onto the market.
There were several questions on the call and Jay said they can use interleaving to make a 50 out of a 100 and I don't have a clue what this means. What are the advantages of a pure 50 vs. a hybrid?
Basically, interleaving is a way to take 2 filters with double the target channel spacing and combine them by interleaving their channels, effectively creating a filter with the desired channel spacing. So you could take 2 100GHz filters and interleave them to create a 50GHz device. To illustrate, if an 80 channel count DWDM system requires 50GHz channel spacings over an operating window (C-band, L-band, whatever), each 100GHz filter would take care of 40 channels within that operating window. One would have the odd channels, and the other would have the even channels. Once combined, the resulting 50GHz filter would cover all 80 interleaved channels in the proper order (odd, even, odd, even, etc).
If what you need is a 50GHz filter, interleaving 2 100GHz filters is a more than adequate way to achieve this. It allows one to use a mature technology and avoid long product cycles which would be needed to create a new technology suited for the narrower channel spacing. Because the mature technology probably has higher yields, interleaving may result in lower overall costs.
So what are the downsides? While you feasibly could interleave up to 4 filters to create 1/4 the channel spacing, it would probably become unwieldy if you needed to scale this further. Therefore, developing a 50GHz filter would allow you to eventually create 25GHz and possibly (I really don't have a clue) 12.5GHz filters through interleaving.
Hope that helps.
Ali |
