The development of silicon based microelectronics means today it costs only a few cents to design and develop per square millimetre of chip, as the technology is mature and highly standardized. In addition, its development costs are low because we have sophisticated software for the fast and accurate design of the chips.Teams at Eindhoven University of Technology, led by Professor Meint Smit, want the same for photonic devices. And now that tipping point has been reached.
“Around the start of this new century, we were all asking ourselves: when is photonics integration really going to take off in the same way as silicon micro-electronics?” explains Smit. “After all, in 1980 I had started saying it would kick start in the 1990. Ten years later, the tipping point had moved to the start of the new millennium. By that time, some critics started to say that the promise of photonics integration would always remain in the future.”
Understanding the success of microelectronics “In Eindhoven, we looked at the world of microelectronics and discovered that things were arranged in a very different way. Up until the 1980's you had a lot of different technologies being used. There were a whole range of transistor types and countless variations between them. But in the 1980's things started converging and you started to see the development of generic processes.”
“Designs start to use the same basic building blocks of transistors, resistors and capacitors. Even some of today’s most complicated processors, with over 1 billion transistors, have less than 10 different components. So you are using the same set of building blocks to create all kinds of things.”
“We asked ourselves, how can this be applied to photonics? If you look to light, it has an amplitude, a phase and a polarisation. So if you make a component for manipulating phase, another for changing polarisation, and one for altering phase, you could achieve a lot of things. Then you simply need a waveguide to connect them.” “So we started developing a process with an optical amplifier for the amplitude, a phase modulator to change the phase, and a polarization converter.”
“There is a big advantage if everyone uses the same generic process. You can combine a lot of different designs on one chip. In a recent successful test case, we had 20 different designs on one wafer.”
There’s always more than one run “The challenge in this business of integrated photonics has been the cost of making a chip prototype. If you develop a chip it always takes 2-3 runs before you get it right, because the chip never performs exactly as you expect.”
“Traditionally, one process run currently costs at least €200,000, if you do it on your own. So this is a huge barrier for small companies. But if 20 users can share the same wafer, then the costs drop to €10,000 each and that's within the scope of many startups. You get 8 identical cells back from the foundry which you can test and measure. You can then iterate the design, so that the next run gives even better results.”
Open Collaboration is key to maintaining Europe’s Lead Eindhoven Technical University (TU/e) also drives and actively contributes to the International JePPix platform. This is an open collaboration between over 240 members, designed to connect researchers, PIC designers, and generic foundries to dramatically cut costs and speed up the time to market. TU/e have also set up Smart Photonics, the only foundry in the world dedicated to the production of low volume Indium Phosphide chips.
“The role of Jeppix is to act as an independent broker between designers and foundry's. We announce a production schedule, collect the designs and produce one big mask. That goes to the foundry that produces the wafers, cuts them up and sends the result back to the various designers. So this is the way TU/e has introduced generic photonics manufacture into Europe.”
The race is on “Clearly, others have recognised we’re on to something. In October 2014, US President Obama reserved US$ 220 million to set up something similar in the United States. Several leading universities and technology companies there are bidding in the tender to create the “Integrated Photonics Institute for Manufacturing Innovation”. Everyone in the industry is waiting to see which city gets to host the institute, because it will mean the creation of many local jobs in the USA for whoever wins.”
“It turns out that the generic integration process is quite complex, so being able to master this gives us a head start. But we’ve reached a very important tipping point. And when we look at the world of semiconductors, no-one thought such generic processes could ever drive very fast 60 GHz radio frequency circuits. Personally, I think if you are willing to invest enough money in a single technology, then it will surpass the rest.”
Indium Phosphide Wins on Price “Now, let’s suppose your chip works and you're happy with its performance. Then scaling up to produce 100,000 pieces is no problem. You can order them immediately knowing that the specs will remain constant. This part can be done using a more traditional process. A large Photonics foundry like Oclaro can manufacture 10,000 wafers a year.”
“The other point is the chip cost. We are actually cheaper. Of course, silicon photonics can make their chips cheaper if you buy a million, but few small companies want a million. They want to start with a few hundred or a few thousand. And if you want a few hundred from a silicon foundry then the entry/set-up costs are very much higher than in photonics. So if you look at the functionality per Euro, Indium Phosphide wins and we are very competitive in the lower volumes.”
“The next step, and we have the first products lined up for that, is to do the whole thing again but then not on a substrate of Indium Phosphide, but on Silicon. But then we will add a very thin layer of Indium Phosphide.”
Riding the Seven League boots of Silicon “The holy grail of this industry is to put lasers onto a piece of Silicon. Silicon itself is not suitable for this - you can't generate light directly, whereas with Indium you can generate light directly on the substrate. We’ve validated methods to build a photonic component on an Indium Phosphide layer and then connect it to a Silicon layer underneath. We are in the process of launching the first working devices.”
“We think that Indium Phosphide will champion by using the “seven league boots of silicon” and we believe our generic approach will scale faster.”
Mark your calendar for 23 September On Wednesday September 23rd 2015 there will be a one-day conference at High Tech Campus Eindhoven. It is dedicated to the huge business opportunities that lie ahead for integrated Photonics as described by Professor Meint Smit. The meeting will also showcase surprising examples of applications for photonics that are just round the corner.