Ranovus delivers direct detect optics for 200Gb/s DCI

Optical start-up Ranovus has announced general availability of its 200G on-board optics and CFP2 direct detect transceivers. It plans to demonstrate both devices in partnership with ADVA Optical Networking at the upcoming OFC Exhibition in San Diego, California.

This is an important milestone for the company and its technology. Founded in 2012, Ottawa headquartered Ranovus aimed to commercialise quantum dot laser (QDL) technology on a silicon photonics integration platform. The initial market targeted is high-speed, data centre interconnect (DCI) and metro access applications over distances up to 80km.

‘After a series of successful trials over the last year, we are pleased to announce the general availability of our product portfolio that enables scalable multi-terabits bandwidth connectivity in form factors that consume less power and are at a third the cost of coherent and half the cost of other PAM4 direct detect transceivers per Gb/s,’ said Hamid Arabzadeh, chairman and CEO at Ranovus.

The availability of a direct-detect option at 200G – an emerging data rate for next-generation servers and switches – will provide greater flexibility for equipment vendors and their customers. Ranovus’ direct detect CFP2 transceiver is form factor and pin-out compatible with coherent modules, allowing the same line card to support both coherent and direct detect configurations.

While ‘coherent is a good technology for a lot of applications’, it is not suited to all distances, explained Saeid Aramideh, co-founder and chief marketing and sales officer at Ranovus. ‘In a lot of cases, especially in China, distances are short, and coherent is overkill for that market, so we’re seeing traction for that market,’ he said.

The company expects 200G will be the dominant data rate for these applications until 400ZR comes along, probably in mid-2019. 400ZR is the standard being developed by the Optical Internetworking Forum (OIF) for a low-cost single-wavelength coherent transmission format at 400G, dubbed ‘coherent lite’.

Direct detect optics use multiple wavelengths – in this case, 4 x 56Gb/s to produce 200G – and that’s where quantum dot lasers come in. The ‘dots’ can be engineered to produce a variety of wavelengths from the same device. Quantum dot lasers are used in the medical and display industries, but this is the first time the technology has been commercialised at 1550nm communications wavelengths, Aramideh said.

The lasers are combined with ring resonators, which are compact waveguide structures that select and modulate the optical signal. The use of ring resonators, which provide an ‘optical bus’ function, means that no mux/demux function is required on the chip. The resulting highly integrated devices have a much smaller footprint, which gives a better manufacturing yield, which in turn means a lower-cost end product, according to Aramideh.

Ranovus says its products are now in lab trials with multiple optical networking equipment vendors. The product demonstration with ADVA will showcase transmission of live traffic over Ranovus’ on-board optics integrated into ADVA’s FSP 3000 CloudConnect terminal, as well as Ranovus’ 200G CFP2 modules. Both optics will send signal over 80km of standard singlemode fibre utilizing ADVA’s open line system (see ADVA shipping open line system for direct-detect DCI).

The demonstration validates the continued use of direct detect technology as data rates increase, according to Christoph Glingener, CTO/COO at ADVA. ‘In partnership with Ranovus, we have made impressive progress to validate direct detect technology as an effective way for data centre operators to lower their cost per bit and improve energy efficiency,’ he said.

Ranovus’ 200G CFP2 and optical engine products support transmission distances of 15km, 40km and 80km+. The products offer 96 DWDM channels in the C-band now and will support L-band in the future. The company is using Broadcom’s 56Gb/s PAM4 PHY with multiple programmable FEC options to optimise link performance.

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