Books in 2018
Gazettabyte has asked various industry executives to discuss the books they have read in 2018. Here, Valery Tolstikhin and Alexandra Wright-Gladstein give their recommendations.
Valery Tolstikhin, president and CEO of Intengent, a consultancy
I read too many technical and business texts during the day so I leave my bedtime for more human reading.
Valery Tolstikhin
This year I wasn’t too lucky with fiction books but I did read some great non-fiction ones: Homo Deus: A Brief History of Tomorrow by Yuval Noah Harari, Jordan Peterson’s 12 Rules for Life: An Antidote to Chaos and Leonardo Da Vinci by Walter Isaacson.
All three titles are bestsellers and do not need an introduction, but still.
Harari’s book - the second in the series, and there is a third already published - encourages you to think of the big issues by detaching yourself from everyday routines and trivia.
Peterson’s book is about how to make yourself comfortable with these very routines and trivia while remaining at peace with the big issues. The book is also music to the ears of conservatives.
Isaacson’s book is as much about Leonardo da Vinci as it is about human’s aspiration for harmony, which extends from the arts to physics theories to iPhone design.
I highly recommend all three.
Alexandra Wright-Gladstein, co-founder of Ayar Labs
I'd recommend Measure What Matters: How Google, Bono and the Gates Foundation Rock the World with OKRs, by John Doerr, and Daring to Drive: A Saudi Woman's Awakening by Manal al-Sharif.
Alexandra Wright-Gladstein
Measure what Matters is a great overview of how several of the top companies of our time use the management method known as OKRs (objectives and key results), first developed by Andy Grove of Intel, to motivate large teams to accomplish impressive goals.
John Doerr learned the method early in his career while at Intel. Then, when he became a VC investor, he started teaching the method to the companies he invested in, including Google.
It is great that the method is now available for the rest of us.
Daring to Drive is just a wonderful story, a page-turner I could not put down. It is the autobiography of a woman who was raised in a conservative part of Saudi Arabia, who eventually revolted by driving a car (an illegal act for women in Saudi Arabia) and putting a video of her doing so on YouTube.
The book came out last year. This year we felt the impact of her life's work and the book when the Saudi government legalised driving for women - an incredible win for Manal and her community.
An insider's view on the merits of optical integration
Tolstikhin is president and CEO of Intengent, the Ottawa-based consultancy and custom design service provider, and an industry veteran of photonic integration. In 2005 he founded OneChip Photonics, a fabless maker of indium phosphide photonic integrated circuits for optical access.
One important lesson he learned at OneChip was how the cost benefit of a photonic integrated circuit (PIC) can be eroded with a cheap optical sub-assembly made from discrete off-the-shelf components. When OneChip started, the selling price for GPON optics was around $100 a unit but this quickly came down to $6. "We needed sales in volumes and they never came close to meeting $6," says Tolstikhin.
OneChip changed strategy, seeing early the emerging opportunity for 100-gigabit optics for the data centre but despite being among the first to demonstrate fully integrated 100-gigabit transmitter and receiver chips – at OFC 2013 – the company eventually folded.
When OneChip started, the selling price for GPON optics was around $100 a unit but this quickly came down to $6
Integent can be seen as the photonic equivalent of an electronic ASIC design house that was common in the chip industry, acting as the intermediary between an equipment vendor commissioning a chip design and the foundry making the chip.
Integent creates designs for system integrators which it takes to a commercial foundry for manufacturing. The company makes stand-alone devices, device arrays, and multi-function PICs. Integent uses the regrowth-free taper-assistant vertical integration (TAVI) indium phosphide process of the California-based foundry Global Communication Semiconductors (GCS). "We have also partnered with a prominent PIC design house, VLC Photonics, for PIC layout and verification testing,” says Tolstikhin. Together, Intengent, VLC and GCS offer a one-stop-shop for the development and production of PICs.
III-V and silicon photonics
Tolstikhin is a big fan of indium phosphide and related III-V semiconductor materials, pointing out that they can implement all the optical functions required for telecom and datacom applications. He is a firm believer that III-V will continue to be the material system of choice for various applications and argues that silicon photonics is not so much a competitor to III-V but a complement.
"Silicon photonics needs indium-phosphide-based sources but also benefits from III-V modulators and detectors, which have better performance than their silicon photonics counterparts," he says.
He admits that indium phosphide photonics cannot compete with the PIC scalability that silicon photonics offers. But that will benefit indium phosphide as silicon photonics matures. Intengent already benefits from this co-existence, offering specialised indium phosphide photonic chip development for silicon photonics as well.
"Silicon photonics cannot compete with indium phosphide photonics in relatively simple yet highest volume optical components for telecom and datacom transceivers," says Tolstikhin. Partly this is due to silicon photonics' performance inferiority but mainly for economical reasons.
Silicon photonics will have its chance, but only where it beats competing technologies on fundamentals, not just cost
There are also few applications that need monolithic photonic integration. Tolstikhin highlights coherent optics as one example but that is a market with limited volumes. Meanwhile, the most promising emerging market - transceivers for the data centre, whether 100-gigabit (4x25G NRZ) PSM or CWDM4 designs or in future 400-gigabit (4x100G PAM4) transceivers, will likely be implemented using optical sub-assembly and hybrid integration technologies.
Tolstikhin may be a proponent of indium phosphide but he does not dismiss silicon photonics' prospects: "It will have its chance, but only where it beats competing technologies on fundamentals, not just cost."
One such area is large-scale optoelectronic systems, such as data processors or switch fabrics for large-scale data centres. These are designs that cannot be assembled using discretes and go beyond the scalability of indium phosphide PICs. "This is not silicon photonics-based optical components instead of indium phosphide ones but a totally different system and possibly network solutions," he says. This is also where co-integration of CMOS electronics with silicon photonics makes a difference and can be justified economically.
He highlights Rockley Photonics and Ayar Labs as start-ups doing just this: using silicon photonics for large-scale electro-photonic integration targeting system and network applications. "There may also be more such companies in the making," says Tolstikhin. "And should they succeed, the entire setup of optics for the data centre and the role of silicon photonics could change quite dramatically."
Silicon photonics economics set to benefit III-V photonics
Silicon photonics promises to deliver cheaper optical components using equipment, processes and fabrication plants paid for by the chip industry. Now, it turns out, traditional optical component players using indium phosphide and gallium arsenide can benefit from similar economies, thanks to the wireless IC chip industry.
Valery TolstikhinSilicon photonics did a good thing; it turned the interest of the photonics industry to the operational ways of silicon
So argues Valery Tolstikhin, head of a design consultancy, Intengent, and former founder and CTO of Canadian start-up OneChip Photonics. The expectations for silicon photonics may yet to be fulfilled, says Tolstikhin, but what the technology has done is spark interest in the economics of component making. And when it comes to chip economics, volumes count.
“For III-V photonics - indium phosphide and related materials - you have all kinds of solutions, designs and processes, but all are boutique,” says Tolstikhin. “They are not commercialised in a proper way and there is no industrial scale.” The reason for this is simple: optical components is a low-volume industry.
This is what Tolstikhin seeks to address by piggybacking on high-volume indium phosphide and gallium arsenide fabrication plants that make monolithic microwave integrated circuits (MMICs) for wireless.
“To take photonics out of boutique fabs, you need to do some standardisation and move to a fabless model, then you can load the fabs day and night with wafers,” says Tolstikhin. “That is the only way to make a process mature, reproducible and reliable.”
Tolstikhin has spent the last decade pursuing this approach. “The idea is to use something available in indium phosphide which is relatively close to a pure-play foundry.” A pure-play foundry is a fab that makes chips but does not design, market or sell them as its own products.
Tolstikhin’s first involvement was at start-up OneChip Photonics which developed an indium-phosphide platform that used a variety of photonic devices to make photonic integrated circuits (PICs), based on a commercial MMIC process.
The issue with III-V integrated photonics is that to implement different functions - a passive waveguide and a laser, for example - different materials are needed. “What makes a low-loss passive waveguide, does not work for the laser,” says Tolstikhin.
To overcome this, the wafer is repeatedly etched in certain areas, to remove unwanted material, and new layers grown instead with the required material, a process known as selective-area etch and regrowth. This is a complicated and relatively low-yield process that is custom to companies and their fabs, he says: “This is how all commercial lasers and PICs are made.”
In contrast, MMICs using indium phosphide do not need regrowth, simplifying the process considerably. To use a MMIC fab for an optical design, however, it must be developed in a way that avoids the need for regrowth stages.
“At OneChip we believe we did the first commercial laser - not just the laser but the PIC with it - regrowth-free,” says Tolstikhin. “It was made in a MMIC fab, that is the key.”
“To take photonics out of boutique fabs, you need to do some standardisation and move to a fabless model, then you can load the fabs day and night with wafers”
Wafer economics
To understand the relative economics, Tolstikhin compares the number of wafers - wafer starts - processed in silicon, indium phosphide and gallium arsenide.
One large TSMC fab has 400,000 12-inch CMOS wafer starts a year whereas globally the figure is equivalent to some 70 million such wafers a year. For MMICs, one fab Tolstikhin works with has 15,000 4-inch indium phosphide wafer starts a year whereas a large optical component company uses just a couple of thousand 3-inch indium phosphide wafers a year.
“In photonics, the [global] volumes – even for components going into the most massive markets like PON and the data centre interconnects – are still very low,” says Tolstikhin.
Gallium arsenide is somewhere in between: Win’s fab in Taiwan, which makes power amplifiers for wireless and other MMICs, has 250,000 6-inch wafers starts a year, while TriQuint’s fab in USA, with similar product line in wireless, totals 150,000 6-inch wafer starts a year.
Such volumes are not negligible and exceed all the needs of photonics, he says, enabling photonics to make claims similar to those trumpeted for silicon photonics: a mature process with a well-established quality system and, with its volumes, delivers better economics.
Moreover, if applications that currently are based on indium phosphide could be transferred to gallium arsenide, that would give an order of magnitude economies of scale, says Tolstikhin: “One example is mid-reach single-mode optical interconnects with an operating wavelength around 1060 nm, with gallium arsenide used for the transmitter, receiver and transceiver PICs”.
And while the scale of III-V semiconductor manufacturing may still be much lower than CMOS, the up-front cost involved in using a III-V fab is also much less.
Using III-V semiconductors for analogue electronics like the laser /modulator drivers or the trans-impedance amplifier also delivers a speed advantage: heterojunction bipolar transistors (HBTs) in indium phosphide have been demonstrated working at up to 400 GHz, and these, being vertical devices, do not have their speed scaled with lithography. In contrast, CMOS analog electronics is much slower and its device speed is scalable with lithography resolution. A 130 nm CMOS process, the starting point for silicon photonics, cannot support optical components with bit rates beyond 10 Gbps.
Design house
Intengent, Tolstikhin’s company, acts as a bridge between OEMs building optical components and sub-systems and the III-V foundries making photonic chips for them.
He compares Intengent to what application-specific IC (ASIC) companies used to do for the electronic chip industry. Intengent works with the OEM to specify and design the photonic chip based on its system application and then works with the fab to develop and turn the chip into a product by meeting its design rules and process capabilities.
“The aim is that you can go and design within existing fabs and processes something that meets the customer’s application and requirements,” he says.
Tolstikhin is also working with ELPHiC, a Canadian start-up that is raising funding to develop single-mode mid-board optics. The indium-phosphide design combines analogue electronic circuitry with the photonics.
“It appears the best way [to do mid-board optics] is based on electronic and photonic integration onto one substrate and indium phosphide is a natural choice for such a substrate,” he says.
Tolstikhin makes clear he is not against silicon photonics. “It did a good thing; it turned the interest of the photonics industry to the operational ways of silicon: standardised processes, pure-play foundries, device designs separate from the semiconductor physics, and circuit designs separate from the wafer processing.”
As a result, something similar is now being pursued in III-V photonics.