Guest blog: Is photonic integration market disruptive?

Guest blogger Roy Rubenstein, editor of gazettabyte, offers his take on photonic integration.

Nortel and Infinera have markedly different views regarding photonic integration. And if their company fortunes also differ, there is no doubting both firms’ optical engineering expertise.

Nortel was first-to-market with its 40-Gbps dual-polarization quadrature phase-shift keying (DP-QPSK) system. Kim Roberts, Nortel's director of optics research and one of the engineers that developed the system, acknowledges photonic integration’s role in reducing system cost and size but downplays its importance overall. Useful but not revolutionary, he says.

Infinera’s chief strategy officer, Dave Welch, thinks differently, arguing that the photonic integrated circuit (PIC) is optical networking’s current disruption. Longer-term, its impact on the industry’s supply chain could be as disruptive as the digital camera’s CMOS image sensor – also a PIC – has been on the photography industry, he says.

So who is right? And has photonic integration been overhyped in a hype-starved industry?

Looking more carefully, the two companies may have different takes on photonic integration yet both are on the same page regarding a broader form of integration, that of photonics and electronics.

Nortel’s approach is to push CMOS technology to the extreme to address high-speed transmission impairments at 40 and 100 Gbps. In particular it is using digital signal processing to extend optical transmission systems. This simplifies end-to-end optics even if the resulting DP-QPSK transmit and receive optics is more complex and clearly benefits from photonic integration.

Infinera uses its PICs to ease conversion between the optical and electrical domains. And by designing its system around its PIC, it can trade off performance between the two domains.

Both firms also have impressive high-speed transmission roadmaps. Nortel has discussed up to 1 terabit per wavelength speeds while Infinera has shown 2- and even 4-terabit PICs. To date, Infinera has detailed a 10x40-Gbps DP-DQPSK PIC.

Photonic integration is thus not so much overhyped as still in its infancy.

Surveying the landscape, photonic integration’s impact is limited but then so has been its application.

For high-speed transmission, it is now being used to simplify the design complexity of phase/phase-polarization modulation schemes: DPSK, DQPSK, DP-DQPSK, and DP-QPSK.

For PON, hybrid and monolithic integration are being pursued by Enablence Technologies and OneChip Photonics, respectively, solely to reduce cost. Yet market-leading PON transceiver makers still favor using TO-can discretes and manual labor.

Wavelength-selective-switches have moved away from optical waveguide technology, using free-space optics instead. Here the integration story is at the packaging level. And while JDSU’s XFP-based tunable laser shows how monolithic integration can achieve a milestone form-factor shrink, the compactness is at the expense of optical reach.

Accordingly, all the while the industry is led by conservative service providers, confining system vendors and component players to the constraints of existing DWDM networks, photonic integration’s full potential will be curtailed.

But that could change. At the OIDA photonic integration event held in September, Google presented a talk entitled Life beyond 100 Gbps: Why Photonic Integration is a Must.

Today’s PICs could yet be seen as the equivalent of the first digital cameras. If so, we are still years away from PICs being deployed widely in new architecture-changing platforms, the telecom equivalent of cameras on handsets and even TVs.

Roy Rubenstein
For his gazettabyte article on photonic integration, click here.