ROADMs Get Sized Up

Bigger reconfigurable optical add/drop multiplexers (ROADMs) are en route to next week's OFC/NFOEC in San Diego, at least in demo form.

CoAdna Photonics Inc. announced this week that it's got a 1x23 wavelength selective switch (WSS, the switching element at the heart of a ROADM) to demonstrate at the tradeshow, and JDSU (Nasdaq: JDSU; Toronto: JDU) noted yesterday that it's going to demo a 1x23 WSS as well. (See CoAdna Intros WSS, TFA and JDSU Shows at OFC/NFOEC.)

Each is laying claim to the industry's "first" 1x23 WSS. Which one is right might depend on who gets to the door of the San Diego Convention Center first.

The 1x23 switches (dropping up to 23 wavelengths from an incoming DWDM stream) has been presumed to be the next size for ROADMs, after the 1x9 size that's the current maximum. A presentation from Finisar Corp. (Nasdaq: FNSR) at last year's OFC/NFOEC put probable systems deployment in the 2011 timeframe -- and, yes, Finisar is working on a 1x23 device as well, apparently called the HWP.

As for the choice of 23 ports: The number was floated by Cisco Systems Inc. (Nasdaq: CSCO) some years ago and just stuck in the industry's consciousness, according to Jonathan Homa, vice president of business development for Xtellus Inc. That's from a conversation that took place before Xtellus's acquisition by Oclaro Inc. (Nasdaq: OCLR). (See Oclaro Makes Its ROADM Bid and Why Oclaro Picked Xtellus.)

Vendors of wavelength-selective switches, the switching elements that are the heart of ROADMs, seem to agree that the market will settle into three groups of products:

• Today's typical market, 1x4 to 1x9
• Smaller ones (mostly 1x2) for access networks
• Big ones: 1x23 or even larger

ROADMs already are undergoing an upgrade in a different direction, handling 80 wavelengths instead of 40. That's accomplished by squeezing the DWDM channel spacing more tightly, to 50GHz from 100GHz. Those models are already on the market. (See Finisar Climbs ROADM Ranks.)

The other advancement that's expected is a move toward ROADMs with more than one input -- NxN or NxM, as they're called. Such devices would be useful in the case of mesh networks, and they've drawn academic interest from the carriers, according to multiple vendors, but not in the form of any requests for quotations (RFQs) yet.

"I don't have an exact timeframe, but it's going to be a while," says Craig Iwata, JDSU's manager of corporate marketing.

— Craig Matsumoto, West Coast Editor, Light Reading