Half a laboratory reduced to fit a picnic table

Highly economical, very inexpensive and much smaller; these are the key characteristics of optical chips. By employing optical circuitry, measuring systems that currently fill half a laboratory can be reduced in size to fit on a picnic table or even slip into a jacket pocket. XiO Photonics has been working with light-manipulating chips for years. The company, based in Enschede, the Netherlands, has a whole library full of solutions based on photonic building blocks and produces applications for the medical and food industries, as well as for Life Sciences, among others.

XiO Photonics recently helped a company to find a solution for a relatively complex measurement set-up. A special biosensor with a blood sample was lit from four sides in succession. In order to do this, the company switched between four laser sources. One of the chips from XiO Photonics’ library has since replaced three of the four laser sources. The chip is linked to a single laser source and incorporates an optical switch, which acts as a kind of traffic warden. It decides which turn-off the laser light should take. The chip’s four outlets are linked to the biosensor, so that the light falls on the blood sample from the correct angle at the right time.

The measurement set-up is shrunk even further through the use of another application that XiO Photonics is keen to highlight: a tiny chip that stabilises the laser light simply by placing it behind the laser source. This is currently achieved elsewhere in the world through the use of a large box of electronic equipment. The changes described above make the measurement set-up more user-friendly, portable, robust and precise.

This approach illustrates a fundamentally different method of thinking in terms of the transportation of light from the source to the place it is needed by the researcher or technician. This can be of benefit to life science researchers, doctors or biophysicists. Take, for example, confocal microscopy; a decades-old technique that uses a laser source to obtain a pinpoint-accurate 2-D or 3-D image from a sample of tissue or food substance. The light from the laser source(s) is often still manipulated in the classic way, using components such as lenses, prisms and semi-transparent mirrors. These kinds of component are also used to combine or split laser beams. The path from the laser source to the sample is therefore long and circuitous, while the measuring equipment is space- and power-consuming. The equipment is often highly sensitive to vibration and relocation is usually not an option.

These limitations in the light delivery path barely apply when using integrated circuits, for instance in confocal or fluorescence microscopy. Miniaturisation is the key word: all of these components can be integrated in chips with a surface area that’s a hundred times smaller. The chips are able to manipulate laser beams, for example by changing their course, focusing them, combining them or even splitting them. One product that XiO Photonics has developed is a plug-and-play box that can combine up to eight different wavelengths and can be linked to other optical components using glass-fibre cables. This can be a very complex operation using mirrors and prisms. Manipulating light using simple, connectable chips makes confocal microscopy more robust, precise, smaller, more mobile and therefore more user-friendly than conventional techniques. Basically, virtually any microscopic technique, such as endoscopy or fluorescence scanning, can be miniaturised in this way.

XiO Photonics is also currently carrying out research into improving the head-up display in cars, a technology that has become increasingly commonplace. The gauges and meters in the dashboard are projected onto the windscreen making driving safer, since drivers can keep their eyes on the road at the same time.
The technology behind this is also largely based on integrated optics. The gauges and meters are split up into coloured pixels, which consist of combinations of red, green and blue. Each pixel is converted into a laser beam containing a certain amount of red, green and blue. The laser beams are projected onto the windscreen in quick succession, pixel by pixel, by means of a rotating mirror and electronic components. This technology eliminates the need for a lens, since the image on the windscreen is always in focus.

Yet it remains to make an impact. Current systems are hybrid: they combine red, green and blue laser beams with mirrors and prisms. By using a beam combiner on a chip, such as the one developed by XiO Photonics, the projection system can be much smaller, cost effective and robust.

Source: XiO Photonics and RVO.nl

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