May 2008 Archives

It's not everyday that you can apply to be an astronaut but today is that day. The European Space Agency (ESA) has posted many people's "dream job" advert and is looking to appoint four individuals to its European Astronaut Corps. There has not been a selection campaign since 1992, so this is a rare opportunity to be part of future missions to the International Space Station, the Moon and beyond.

Prospective candidates can now carry out the first step of the application procedure by filling in details online. The deadline for applications is 16 June 2008.

All shortlisted candidates will go through a series of selection procedures and at the end of the day, four lucky individuals will begin basic training at the European Astronaut Centre in Cologne, Germany. The final appointments will be officially announced in 2009.

So, what qualities is ESA looking for? Well, optical scientists will certainly be in with a chance. "The ideal candidates should be competent in relevant scientific disciplines, such as life sciences, physics, chemistry and medicine and/or be an engineer or experimental test pilot," says ESA.

And if you have ever suffered in a lab trying to make your experiment work, you will certainly relate to some of these additional qualities. "Applicants should also have demonstrated outstanding abilities in research, applications or the educational field, preferably including operational skills. A good memory and reasoning ability, concentration, aptitude for spatial orientation and manual dexterity are also prerequisites."

Applicants have to be fluent in English (with Russian being an asset) and should have high motivation, flexibility, team competence, empathy with others and emotional stability.

Right, I'm off to apply and search for a book on "Beginners Russian for Prospective Astronauts".

On May 16th 1960, Theodore Maiman changed the world when he demonstrated the world's first working laser. He made his breakthrough at Hughes Aircraft Corporation, by generating pulses of coherent light from a fingertip-sized lump of ruby illuminated by a flash lamp. The exact attribution of the invention has historically been a little problematic. Maiman beat a number of other physicists to the post, including Charles Townes who had earlier developed the maser, a microwave forerunner of the laser, while Townes' student Gordon Gould coined the actual word "laser".

How ever the credit should be apportioned, the results have been extraordinary, with lasers playing a huge role in our lives already and further breakthroughs nearly every day. You can be sure that the achievements of laser developers in the next 48 years will be every bit as remarkable as Maiman's ground-breaking experiment. And that optics.org will bring them to you.

I wasn't at CLEO for the last day, but optics.org publisher Claire Bedrock was. There was one particular talk that caught her eye:

"For those who stayed for the final day of the conference there was a fascinating day-long symposium on hollow-core photonic crystal fibre. The final talk of the day created a particular buzz, when Brian Mangan of Crystal Fibre of Denmark presented some new results obtained in a collaboration with the Technical University of Denmark.

First up was a fibre with an antiresonant core, which achieved an attenuation of 9.3 dB/km ‐ a new record for this type of seven-cell fibre). Then Mangan presented results for two high-birefringence fibres, one with an air-fill factor of 91% and the other with a lower air-fill factor of 85%. The latter produced an impressive attenuation of 19 dB/km.

When questioned at the end about the future of photonic crystal fibre. Mangan replied that 'there are loads of talented guys in the field and I'm sure we'll find a solution to the limitations'. This seemed an appropriate note on which to end not only a fascinating symposium but an exciting conference."

In Thursday's post-deadline session, Liang Dong of fibre laser specialist IMRA showcased a new class of fibre that supports singlemode operation for fiber laser applications requiring high peak powers. According to Dong, the new all-glass fibre will extend the reach of practical ultrafast amplifiers to millijoule pulse energies, and could also lead to continuous-wave fibre lasers and amplifiers in the 10 kW range.

Dong explained that high peak powers requires singlemode operation to be achieved in a fibre with a large effective area. He pointed out that today's large-mode area fibres are limited to a core diameter of 30 µm, while photonic crystal fibres have been demonstrated with diameters of up to 100 µm.

Those figures make it even more impressive that IMRA has achieved singlemode operation in fibres with core diameters of up to 170 µm. The fibres exploit the company's "leakage channel fibre" (LCF) design, in which the core of the fibre is formed by six low-index features arranged in a hexagonal grid. Unlike photonic crystal fibre, in LCF the air holes are filled with flourine-doped silica glass, and so it can be cleaved, spliced and handled in the same way as normal optical fibre.

Versions of the fibre with core diameters of 100 µm and 170 µm were designed as passive LCFs. The 100 µm version achieves a pump absorption of more than 25 dB/m &ndash which Dong says would mean that a typical amplifier could be just tens of centimetres long – while LCFs with larger diameters could yield even shorter amplifiers.

A ytterbium-doped LCF was also fabricated with a core diameter of 50 µm. A single-stage amplifier constructed from this fibre achieved pulse energies of 600 µJ for a pulse length of 600 ps and a repetition rate of 25 kHz, which Dong says shows that "the design is a practical choice for extending the peak power in fibre lasers".

Keen-eyed delegates may have been intrigued by the signage for PhotonXpo scattered around the CLEO exhibit hall.

Well, all was revealed this morning: it's part of a rebranding exercise for the CLEO technical exhibit. "The goal is to provide the exhibit with its own identity," Colleen Morrison, the OSA's director for for public relations, told me today. "It has continued to expand, and we wanted a name that would better reflect what's out there on the show floor."

This year's CLEO attracted 320 exhibitors, but the organizers hope that renaming the event will increase numbers at the 2009 event in Baltimore, Maryland.

And that's it from me for now. I'm off to the airport for the red-eye flight to London, but look out in the next couple of days for a couple of post-deadline posts.

The growing interest in commercial photovoltaic sources was apparent at Wednesday afternoon's PhAST session. A full conference room heard Craig Cruikshank of cintelliq, a UK consultancy specializing in organic semiconductors, explain how increased research funding into organic photovoltaics (OPVs) would lead to increased efficiencies and lifetimes, but that the real challenge will be to manufacture devices in high volume and at low cost.

For the moment, he said, the efficiency of OPVs is limited to around 5%, but manufacturers such as Konarka have claimed that improved materials and device architectures will increase that figure to 20% by 2015 – which is comparable to that of silicon solar cells. But he said that widespread adoption of OPVs would not happen until the cost per watt approaches that of conventional power generation systems.

That theme was picked up by James Dietz of Plextronics, a US-based manufacturer of OPV materials. He said that falling prices for OPV systems, combined with rapidly increasing rates for electricity producing using conventional means, would enable OPVs to reach grid parity in around 2015. "Analysts predict that demand for OPVs will outstrip supply once grid parity is reached," he said.

In the meantime, said Dietz, OPVs will be limited to niche applications. One key market lies in micro-powered consumer devices, for example to reduce the battery power required in toys and handheld devices. OPVs are particularly suited to this type of power scavenging application, since they maintain good efficiency at low light levels – such as you might find indoors.

Finally, both Dietz and Cruikshank issued a warning about the accuracy of efficiency and lifetime measurements claimed by OPV manufacturers. The methodology for taking these measurements has not yet been standardized, which can lead to some misleading figures. According to Dietz, Plextronics and other companies are now working with the National Renewable Energy Laboratory (NREL) – which currently runs a certification programme for OPV measurements – to define future standards.

At Wednesday's plenary session, the OSA recognized the achievements of key optical scientists and engineers in its annual awards ceremony.

A popular winner was Ursula Keller of ETH Zurich, who was presented the Joseph Fraunhofer award for her work on ultrafast lasers, notably semiconductor saturable absorber modelocking. We have already reported on Keller's latest research into integrated modelocked VECSELs, and she clearly felt honoured to receive such an award. She pointed out that her two sons, aged 9 and 11, were in the audience "to see why Mommy is away all the time".

In her acceptance speech, Keller urged women scientists to continue to do good science, but also to remember to have a family. "You can do it," she said. "It may be tough at times, but you just need to try harder."

Other winners were:

* Eric Mazur of Harvard University was awarded the Esther Hoffman Beller Medal, which is presented for contributions to optics education. Mazur won the award for developing a teaching methodology known as "peer instruction", which promotes deeper understanding of the fundamentals of science.

* Kam Y Lau, professor emeritus at the University of California, Berkeley, was awarded the Nick Holonak Jr. Award for his work on high-speed direct modulation of semiconductor lasers through enhanced differential gain.

* Robert R Alfano of the City College of New York won the Charles H Townes award for his contributions to the discovery and investigation of supercontinuum sources, and the development of tetravalent chromium-based tunable solid-state lasers. By a happy coincidence, Alfano also celebrated his birthday today.

Finally, the 2008 Student Award, which is sponsored by New Focus, was decided on Tuesday night in a competition between seven finalists. Each finalist presented a research paper to a panel of judges, as well as to a "live" audience, and the winner was Richard Sandberg of JILA and the University of Colorado at Boulder. Sandberg receives $5000 as part of his award, while the runners up each receive $1500.

One of the most eye catching displays at this year's CLEO exhibit can be found on Paradigm Lasers' booth. Its o-Tool product offers a simple visual display that allows users to quickly and easily assess the light output from a laser source. It can be used by scientists to instantly visualize the output intensity from their light source, and by educators to demonstrate the concept of polarization.

Company president Tim Irwin told me that the o-Tool provides the same ease-of-use for optical systems as a multimeter provides for electronic systems. "Full characterization of an electrical system requires an oscilloscope, but all labs have a multimeter to quickly measure voltage and current levels," he said.

Before use, the o-Tool just needs to be plugged in and energized by shining a light at a side hole. Directing a laser at the centre of the instrument then generates a response that depends on its intensity, and an optional infrared attachment makes it possible to "see" the output from an IR source.

An additional polarization plate makes it possible to visualize the direction and intensity of a polarized light source. Irwin believes this could be a real winner in a teaching environment, since it would allow students to see the effect of waveplates and polarizing sheets on the laser output. With the basic instrument retailing for around $225, it could be a worthwhile investment.

At the CLEO exhibit today, Paul Morris of Gooch & Housego gave me a sneak preview of a prototype fibre Q-switch that is significantly smaller than an earlier device that delivers similar performance (see picture). According to Morris, the innovative device is a direct result of the integrated strategy that Gooch & Housego unveiled back in January.

The fibre Q-switch is designed to boost the output of pulsed fibre lasers operating in the 20–40 W range. According to Morris, the small size of the device was achieved in part by reducing the size of the crystal, drawing on the expertise of the company's main site in Ilminster, UK. But it also exploits fibre packaging know-how acquired from the former SIFAM business in Torquay, UK, to efficiently couple light into the crystal and so eliminates the need for bulk optics to achieve good alignment.

Morris said that Gooch & Housego is currently previewing the device to key customers in the fibre laser space. A formal launch is scheduled for Q3 – at which time a full technical spec will be released – while manufacturing of the device is slated to start by the end of the year.

The size of the market for such a fibre Q-switch is not yet clear. Manufacturers of fibre lasers either use fibre amplifiers or Q-switches to achieve pulsed operation at high powers, depending on the performance parameters needed for each application. Morris believes that the compact size of the fibre Q-switch will prove popular, while power levels below 50 W represent a sweet spot for fibre lasers to displace conventional Q-switched lasers in marking applications.

Also in the pipeline is a scalable fibre isolator technology. Isolators are needed in all fibre lasers to prevent reflected laser light from damaging the pump laser diode, but currently they are fabricated one at a time in a lab-based environment. Gooch & Housego is now working on a fibre isolator that would allow for higher throughputs, and Morris said that formal announcements are likely to be made towards the end of this year, or early in 2009 – no doubt in time for next year's Photonics West.

All-optical data processing at ultrafast speeds is the goal of researchers at Sandia National Laboratories in Alberquerque, New Mexico. In today's conference session on high-speed components, Sandia's Gordon Keeler said that the initial aim is to develop a chip-based optical platform that can perform logic operations at speeds of up to 40 GHz, but that the longer term goal is to achieve processing speeds of 100 GHz and beyond.

The critical technology in the Sandia team's research is a self-electrooptic effect device, or SEED for short. SEEDs, which were invented 25 years ago by David Miller at Bell Labs, operate as both a modulator and a high-speed photodetector. Crucially, when two of these devices are put together to form a symmetric SEED (S-SEED), they operate as a bistable device that can be switched by an optical pump.

This means that S-SEEDs can be exploited as all-optical logic gates, in particular to perform both NAND and NOR operations. And, according to Keeler, more complex logic circuits can be realized by cascading several S-SEEDs together using micro-optics.

Earlier work at Sandia demonstrated fast switching times for S-SEEDs fabricated in AlGaAs that operate at 865 nm. Now, however, the team has developed devices in a different material system that deliver similar performance at the more useful telecom wavelength of 1550 nm.

The telecom-compatible S-SEEDs are made from InAlGaAs quantum well structures grown on InP substrates. According to Keeler, the quantum wells are made shallow enough that a few picojoules of energy from a modelocked fibre laser is sufficient to switch the state of the logic gate.

Using this scheme, Keeler and his Sandia colleagues have demonstrated switching times at 1550 nm of down to 5.5 ps, which should yield an operating frequency of 40 GHz. Simulations suggest that all-optical switching in this system shouldbe possible at speeds of up to 100 GHz, but will ultimately be limited by the carrier dynamics in the system.

An intriguing notion was presented this afternoon by Max Shtein of the University of Michigan. Rather than fabricating organic light-emitting diodes as discrete planar devices, Shtein has shown how organic emitters can be formed on 3D structures such as cylindrical fibres and micron-scale cantilevers for use in atomic force microscopy (AFM).

Once you think about it, the idea is obvious: organic materials have been fêted for their flexible nature, and the weak van der Waals forces that bind organic molecules together are weak enough for the organic layers that make up an OLED to conform to non-planar substrates.

The problem, says Shtein, is the need in conventional OLED structures for transparent electrodes. Indium tin oxide (ITO) is the usual choice, but remains an expensive option for large-area deposition. And ceramic materials that also combine optical transparency with good electrical conductivity must be deposited at high temperature – which increases the fabrication cost – and are too brittle to be used on curved substrates.

The solution for Shtein and his team is to replace the transparent electrodes either side of the organic layers with thin metal films. Tests on a planar metal–organic–metal (MOM) structure emit light efficiently, but the spectral content varies with viewing angle. In contrast, forming the MOM structure on a cylindrical fibre substrate yields uniform colour output at all viewing angles.

More intriguing still is the idea of depositing OLED structures onto an AFM tip. This enables localized current injection at the vertex of the tip – largely because the sharpness of the tip concentrates the electric field and so increases the current density – which leads to controlled light emission at the vertex of the tip.

What's more, says Shtein, the fabrication process is scalable, and so could allow OLED structures to be deposited onto an array of AFM tips in a single process run. "The ability to fabricate nanoscale light sources on commercial AFM cantilevers could enable new applications in high-resolution optical scanning microscopy, as well as nanoscale optical and chemical sensing," he said.

The first fibre-based laser to deliver picosecond pulses at high average power levels took pride of place when I visited Coherent's booth this morning. According to Matthias Schulze, Coherent's director for product marketing, the Talisker laser is targeted at industrial micromachining applications where high precision and high throughput are critical for success.

Schulze told me that nanosecond Q-switched lasers operating at ultraviolet wavelengths have become the industry standard for machining materials such as silicon at the micron scale. But he says that in some cases the Talisker laser could offer the same performance at infrared wavelengths, which would eliminate the need for costly UV beam delivery systems.

Indeed, the Talisker laser can switch operation between three wavelengths. UV output at 355 nm enables ultraprecise machining with an average power output of 4 W, while the laser can also produce visible output at 532 nm and infrared at 1064 nm – in which case the average power output rises to 18 W. In each case, the pulse repetition rate is 200 kHz, which equates to a pulse width of less than 15 ps.

According to Schulze, this flexibility will allow customers to evaluate which wavelength works best for their particular application. "If infrared picosecond pulses provide the same precision as a UV nanosecond laser, Talisker would make it possible to increase throughput and lower the system cost without compromising on precision," said Schulze.

According the Schulze, the combination of ultrafast operation and high output power Talisker is only possible with a hybrid design. A fibre-based laser oscillator provides a stable and robust source of picosecond pulses, while a free-space amplifier boosts the peak power to levels some ten times greater than is possible with a fibre laser on its own.

Schulze says that the laser could be used for micromachining applications in the microelectronics, biomedical, and solar cell industries, and that customers are currently evaluating its use with a range of materials. He also mentioned that Talisker is just the first in a series of fibre-based products that Coherent will be launching to address materials processing applications at the micron scale.

* Also new for CLEO, and aimed more at the research community, are two new ultrafast amplifiers that now offer pulse widths of less that 25 fs. The Legend Elite USX-HE offers pulse energies of more than 2.5 mJ, while the Duo-USX model delivers pulse energies in excess of 5 mJ.

According to Marco Arrigoni, director of marketing for Coherent's scientific business, this is the first amplifier to achieve such short pulse widths – which are needed in research applications such as ultrafast spectroscopy, high-harmonic generation, and attosecond physics. This performance is achieved by a regenerative amplifier module combined with Coherent's BandMax technology, which ensures stable short-pulse generation.

According to Phil Wright of the Optoelectronics Industry Development Association (OIDA), sales of commercial OLED lighting products will reach $14 bn by 2020. Speaking at today's PhAST conference, which is held in conjunction with the CLEO exhibit, Wright said that OLED backlights for LCD screens would be the first application to drive widespread market adoption.

"OLEDs will start to displace other backlight technologies by 2010, and it will still be the largest single market for OLEDs in 2020," he said. "Illumination applications will be the second largest market by 2020, followed by automotive and signage."

Wright believes that early adopters of OLEDs for illumination will be lighting engineers who want to make a bold design statement. Otherwise, OLEDs face stiff competition from incumbent technologies, including compact fluorescent bulbs and inorganic LEDs.

Further penetration of OLEDs into the lighting market will require further improvements in luminous efficacy and lifetime, combined with a reduction in manufacturing costs. Wright pointed out that the US Department of Energy predicts that laboratory devices will achieve efficiencies of 150 lm/W by 2012, with the same figure being attained by commercial devices a few years later. Lifetimes are also expected to reach 40,000 hours by 2015, while the cost of production is predicted to fall to $10 per thousand lumens over the same time frame.

A full conference session this afternoon heard Ursula Keller of ETH Zurich describe a new type of ultrafast semiconductor laser called the MIXSEL – which stands for modelocked integrated external-cavity laser. MIXSELs promise to deliver high output powers at repetition rates of 10–100 GHz, parameters that Keller says are needed in biomedical applications, optical clocks for computer processor cores, and telecoms applications.

The MIXSEL design is the culmination of several years' work on passively modelocked vertical external-cavity surface-emitting lasers (VECSELs), which were first demonstrated by Keller's group in 2000. Indeed, the latest modelocked devices achieve an average output power of 2.1 W at pulse durations of less than 500 fs and repetition rates of 50 GHz – which Keller says is competitive with the performance of diode-pumped solid-state lasers.

However, these headline results were obtained from a hybrid structure consisting of the VECSEL gain medium and a separate semiconductor saturable absorber mirror (SESAM), an arrangement that poses problems for high-volume wafer-scale fabrication. Keller's group has therefore been working to integrate the SESAM functionality into a single laser architecture.

The result of these efforts is the MIXSEL structure, which consists of five sections: a distributed Bragg reflector (DBR) that is highly reflective at the laser wavelength of 960 nm; a saturated absorber made from self-assembled InAs quantum dots embedded in GaAs layers; an intermediate DBR for the pump wavelength at 808 nm; the gain section with seven InGaAs quantum wells; and an anti-reflection coating.

Initial results for this structure showed an average output power of 182 mW with a pulse duration of 32 ps when the MIXSEL was cooled to –50°C. In this case, however, the power output was limited by the high thermal impedance of the 600 µm GaAs substrate on which the structure was grown. Further power scaling will be achieved by growing the layers in reverse order (the normal "upside down" approach), which will allow the substrate to be removed using selective etching.

The existing MIXSEL design requires optical pumping, but Keller is confident that electrical pumping should also be possible. Further optimization is also needed to produce shorter pulses, potentially down to the femtosecond range, and this will one of the goals of a new European research project to produce compact ultrafast sources for biomedical applications.

Near-field pattern

At my first CLEO talk of the day, Susumu Yoshimoto and colleagues at Kyoto University in Japan described an electrically pumped GaN laser that emits blue-violet wavelengths at room temperature. The device is the first GaN photonic-crystal surface-emitting laser (PC-SEL) to operate at room temperature under pulsed current injection.

Just a couple of weeks ago, optics.org reported on a GaN VCSEL that achieves electrically pumped lasing at 462 nm. But Yoshimoto claims that the PC-SEL design could deliver powers of up to 1 W – orders of magnitude greater than can be achieved with both GaN VCSELs and photonic-crystal nanolasers – while also producing a narrower and more controllable beam than is possible with edge-emitting devices.

In the PC-SEL design, a two-dimensional photonic structure is created close to the active quantum-well region of the device. The photonic crystal creates a feedback effect that leads to the generation of a 2D cavity mode, and also acts to couple light emission into the vertical direction. Changing the parameters of the photonic crystal also allows the polarization and the beam pattern of the emitted light to be controlled.

This type of operation has already in demonstrated in GaAs-based structures, but fabricating a PC-SEL in GaN proved more difficult. One key problem, said Yoshimoto, is that the distance between the planar photonic crystal and the active region should be about the same as the wavelength of light in the material, which is shorter in GaN than it is in GaAs.

"To obtain the required band-edge effect, the photonic-crystal structure must be constructed within 300 nm of the active layer," said Yoshimoto. "It also requires the fabrication of a high-quality GaN/air periodic structure with a lattice constant of between 100 and 200 nm."

To meet these exacting demands, Yoshimoto's group developed a new fabrication method known as AROG (air holes retained over growth). In this technique, the periodic pattern is first defined in the GaN epitaxial layer using lithography and dry etch processes, and silicon dioxide is then deposited in each air hole. Another GaN layer is then overgrown using molecular-organic vapour phase epitaxy to cap the top of the air holes, while the silicon dioxide prevents GaN growth within the holes. The result is a well defined arrangement of air holes inside the GaN epitaxial layer.

Tests on the GaN PC-SEL revealed light emission at 406.5 nm, with large-area lasing observed in the near field and a narrow (100 µm²) beam forming in the far field. This replicates the single-mode, large-area oscillation that has previously been observed in GaAs structures.

One remaining challenge is that the laser currently requires a large threshold current, at around 6.9 A (67 kA/cm²). Yoshimoto believes that this could be reduced by improving the crystalline quality of the multiple-quantum-well active layer; optimizing the distance between the active layer and photonic; and using a transparent electrode. The target threshold current density for the group is 5.4 kA/cm².

Farmer's market

Most visitors to CLEO from Europe will, like me, have flown on Saturday to get a cheaper airfare. The downside is that you miss a weekend at home (and, for those from the UK, this time it's a holiday weekend), but the upside is that you get an extra day to recover from the flight and the jet lag.

You might wonder what there is to do in downtown San Jose on what has turned out to be a beautiful spring day. Well, so did I.

Luckily for me, a couple of friends recommended that I should stay for the weekend in Los Gatos, a town in the Santa Cruz hills that is only about 15 miles away from San Jose. And I'm glad they did, because Los Gatos is the perfect place to spend a lazy day.

I found plenty of interesting shops to browse in (I particularly liked Powells Sweet Shoppe and Inner Journey, a purveyor of "metaphysical supplies"); a farmer's market with fresh Californian produce that's held every Sunday morning; and great coffee and cake in the Los Gatos Coffee Roasting Company.

There's plenty here for more active types as well. I started my day with a run along the Los Gatos Creek Trail, an off-road track that's clearly popular with walkers, joggers and cyclists. It was certainly enough to give me an appetite for a proper American breakfast.

Tomorrow, of course, I shall be making my way to San Jose for a full day of conference sessions. So enough of my travelog - tomorrow it's back to optics!

Terminal 5

My journey to CLEO started this morning with my first visit to Heathrow's Terminal 5, which opened in March with the aim of easing the chronic congestion at the world's busiest international airport. Sadly, the big opening was dogged by serious baggage handling problems that caused dozens of flights to be cancelled.

Today, thankfully, there was no hint of that earlier chaos. The arrivals hall is light and airy, and seems almost serene – although it's true that the terminal is still only operating at around half of its full capacity. I was even greeted by a calming display of synchronized fountains when I arrived early this morning.

But there were a few telltale signs of those "teething troubles". The fast bag drop wasn't exactly speedy and, although the system for security checks looks high tech, it took just as long as ever to get through. And I'm not sure how well the system will cope when more passengers are going through the doors.

There were other little niggles: the two-level departures area is confusing to navigate, and a simple map of the facilities would have been a big help. And although the restrooms look great – and feature those fab ultrafast hand-drying machines – some of the door locks don't work properly.

T5 fountains

All of these problems will, I'm sure, get sorted out in the coming weeks and months. But there is one big design flaw: although the shops and eateries in the departure area are arranged over two floors, there are no stairs (that I could find) and no "up" escalators – but there are two "down" escalators. Where's the logic in that?

The acid test, of course, is whether the flight left on time. In this case, we boarded the plane on time (well done, T5!), but had to wait 40 minutes for a runway slot. So T5 may well alleviate the congestion in the terminals, but Heathrow's runways are just as busy as ever.

PS. For those who aren't interested in the numerous shopping opportunities that T5 has to offer, I can recommend Gordon Ramsay's café/restaurant "Plane Food" as a peaceful haven with an outside view (nice planes!)

The CLEO/QELS event kicks off on May 4th and runs through to May 9th, drawing the optics and photonics community to San Jose's McEnery Convention Centre for one of the showpieces of the optoelectronics calendar.

This year's technical programme will see more than 1800 technical presentations alongside short courses, tutorials, symposia and poster sessions. Hot topics this year include plasmonics and nanophotonics, single-chip integration and fibre lasers.

"The total submissions to the programme are up by 10%, and for some topics it's nearer 20%," said Aephraim Steinberg, co-chair of the QELS programme. "We've extended the technical programme to a full five days to make room."

Over 350 exhibitors will take part in the trade exhibition, while students, job seekers and employers alike can visit the Career Centre to attend workshops and network.

"CLEO has a niche, giving a breadth of coverage while ensuring very high quality," said Konstantin Vodopyanov, CLEO programme co-chair. "It's the universal clock, creating the rhythm in the field. It's like a heartbeat."

You can stay close to that heartbeat by reading the optics.org CLEO show blog, where our reporters will be bringing you the latest developments and the hottest news. Check back regularly as the show progresses.