Network Photonics Inc. has unveiled an optical switching technology designed to lower service providers’ equipment costs and space requirements by obviating the need for dense wavelength division multiplexers.
Called CrossWave, the technology integrates wavelength demultiplexing, switching and multiplexing to enable dynamic wavelength switching. CrossWave will be a building block for all-optical wavelength cross-connects (WXC) that switch DWDM wavelengths optically without converting them to electrical bits.
This increases network efficiency because it eliminates the need for repeated optical-electrical-optical (OEO) conversions of traffic, Network Photonics says.
In addition to WXCs, Network Photonics says CrossWave can be used to develop dynamic optical add/drop multiplexing (OADM) modules for the metropolitan, long-haul and ultralong-haul networks. The company also says its technology can be used to develop a hybrid cross-connect by combining the WXC capability with grooming optical core switches (OCS). This hybrid OCS manages wavelengths and groomed services, is highly scalable, costs less and can reduce OEO requirements, Network Photonics says.
CrossWave integration is achieved by combining one-dimensional microelectro-mechanical switching (1-D MEMS) technology and a wavelength dispersion element, which is a prism-like component. The dispersion element spatially separates wavelengths from input fibres and focuses them on the surface of a micromirror, where the switching occurs.
The dispersion element then recombines the switched wavelengths into DWDM signals that exit onto desired output fibres.
CrossWave uses a linear array of silicon micromirrors that switch between two positions, such as left and right. Each mirror switches a single wavelength in 100 microseconds, 50 times faster than switching technologies such as 2-D and 3-D MEMS, Network Photonics says.
The mirrors are controlled with simple digital electronics, the company says, which eliminates the need for multiple, more complex components. Network Photonics developed this 1-D MEMS technology internally and has more than 30 patents pending.
Unlike 2-D MEMS or 3-D MEMS technology, Network Photonics says 1-D technology requires a single port per fibre, not per wavelength. The company also claims that its 1-D MEMS technology uses smaller mirrors that occupy a fraction of the chip on which they are housed.
How It Scales
The technology scales in two different ways. First, wavelength count can be increased by increasing the number of mirrors on a 1-D MEMS chip. Second, the fibre port count can be increased by reengineering the CrossWave components, similar to the way an electrical cross-connect fabric is reengineered.
Two-dimensional MEMS technology uses a 2-D array of mirrors, requires one port per wavelength and is usually limited to 1,024 mirrors per chip. It is not easily scalable, as it requires N-squared mirrors for N number of ports, Network Photonics says. As a result, applications for 2-D MEMS are generally limited to less-sophisticated switching requirements.
Three-dimensional MEMS technology uses a 3-D array of mirrors and requires one port per wavelength. It uses 2N mirrors for N number of ports and can scale to thousands of ports. It is typically used for large core-switching applications but is complicated and requires a lot of electronics.
Reliable Business Case
While 1-D MEMS is apparently less complex than 2-D or 3-D MEMS, the value lies in Network Photonics’ financial stability and solid business case for 1-D, says Lawrence Gasman, research analyst for Communications Industry Researchers. By virtue of its simplicity, 1-D MEMS is more likely to be able to guarantee reliability, the No. 1 concern of service providers, he says.
“I’m very impressed with their business case,” Gasman says. “They have brought a realism to the market that the market is not the same as it was a year ago. People keep coming out with these faster and faster chips, and while they are nice, there is no evidence that these products are going to be bought. Network Photonics has addressed several real needs here: reliability, the need for OXCs and the need for OADMs.”
Network Photonics currently has CrossWave systems available for customer and partner testing and plans general product availability for early next year.
