New-Generation Photonic Materials
October 26, 2012
New photonic materials are at the center of a major project being carried out by researchers at the Military University of Technology (WAT) in Warsaw.
The project involves work to develop liquid crystal cells capable of working in outer space and new fiber optic and oxide single crystal technology. The researchers are also focusing on a new breed of infrared detectors.
Prof. Leszek Jaroszewicz, director of the Institute of Technical Physics, talks to Tadeusz Belerski:
The project covers a variety of research areas. Is it a challenge to manage a project as big as this?
Indeed the project is being carried out in four parallel research areas. The aim of the first is to obtain new liquid crystal compounds and develop mixtures and liquid crystal composites as well as to research their applications. The project also covers construction and work on the use of liquid crystals in adaptive optics components, high-speed electro-optical switches, filters, spatial light modulators as well as in optical fibers and in holographic and laser technology. In addition, the project comprises work on the development of new fiber-optic photonic components for use in telecommunications and other sectors.
How did the idea to focus on liquid crystal compounds come about?
We already know where and how these can be used. A big asset is the group led by Prof. Roman D±browski, which can produce materials and liquid crystal mixtures. The professor himself is an internationally recognized specialist in the field of synthesis and study of the physicochemical properties of liquid crystals and in the design of liquid crystal mixtures to achieve different electro-optic effects.
D±browski’s team has developed more than 2,000 new liquid crystal compounds, developed many types of liquid crystal mixtures for optical indicators, valves and converters, temperature and pressure sensors for holography and various telecommunications applications.
It takes a lot of expertise to be able to distinguish a liquid crystal from a mixture. The liquid crystal itself does no good. It acquires value only if it can be applied to some purpose. And that’s not that easy. We are dealing with a liquid for which you have to find an application and “wrap” it into a technical structure. In order to apply a liquid crystal liquid, you must first create a cell—take a pair of flat parallel plates, position them at a distance of 2-3 microns from each other. Then you have to apply a layer of transparent electrodes on these two plates, and connect them.
As a result of the program, we have developed solutions that are fit for application. For example, we have obtained liquid crystal cells that can be used in outer space. We have sent these to St. Petersburg, where they have been used in a system for positioning a Russian Mars rover.
How did it happen that the Russians placed an order for your services?
Nobody wanted to meet the requirements of the Russians. At first, we weren’t planning on taking part in this project, either. It seemed to us that it was undoable. But eventually we went for it. The device contains four positioning system cells so that the Mars rover can sit evenly on the surface. A laser impulse is sent from a long distance that is reflected off the ground and returns to the lander in four bundles, helping it land horizontally. This is a giant laser impulse that passes through the special liquid crystal we have developed in the course of our research.
We already have some experience in this area. We are conducting work at WAT related for example to laser rangefinders in which such cells are utilized, but this is for military uses.
These cells, in a different form applied in other materials, are also used in 3D glasses.
What other kinds of work are being carried out as part of the project?
Another research area being pursued by our team as part of the project is fiber optic technology. We have carved out a technological niche for ourselves that involves combining commonly used fiber optics with special fibers, so-called photonic fibers, otherwise known as microstructural fibers.
In a single-module fiber of 125 microns, there are holes with a diameter of 1 to 3 microns in the middle.
And it is possible to inject a liquid crystal, for example, into these holes and control the process. However, the problem is how one structure should be connected with another. We do the best job in the world making such connections because we have found our own way. I deal with fiber-optic technology, not with the use of fiber optics for transmitting information, but as detectors of gas or hazardous substances. Microstructural or photonic fibers with a fiber optic structure are the material of the future. The main problem is how they should be connected. For some fibers, we have been able to develop such linking technologies. The future belongs to plastic fibers that could be sewn into clothes. In such a uniform a firefighter can be warned against high temperatures, and the soldier against a high concentration of chemicals.
Yet another research area is the development of technology for new single crystals and inorganic glasses, especially oxides, including those containing quantum dots. The research focuses on composites containing ferroelectric single crystals and liquid crystals. Work is also under way on the development of technologies for new single oxide crystals, new inorganic glasses, including those containing rare earth and quantum dots, as well as composites containing organic and inorganic nanocrystals. These materials are very important for optoelectronics.
Does the project include research topics carried out for specific orders from companies?
Yes, we are working on new infrared detectors and uncooled detectors. This research is being carried out by a group led by Prof. Antoni Rogalski, an expert on infrared detectors, a correspondent member of the Polish Academy of Sciences who is known internationally. This work is being carried out on the basis of an order placed by spin-off company Vigo System SA established by WAT professors. This is the kind of application which we will deliver to them for implementation. Clearly, in addition to research, this is pure business. This spin-off company produces detectors developed by our scientists, which are among the best in the world. NASA wants to use them in a project to search for signs of life on Mars.
A further research area as part of the project involves the development of new quality materials for hydrogen storage. Hydrogen has a future. Using it to power vehicles involves the problem of storage. Material with excellent sorption and absorption properties is needed. At the moment, it is possible to build a car fitted with hydrogen batteries. The problem is not the pressure of 100-200 atmospheres, because there are highly durable materials, but the temperature in the order of 300 degrees Celsius. This is too much for the gas to be stored on an industrial scale. We are working on using nanomaterials, appropriate mixtures of nano-scale materials that make it possible to reduce the storage temperature. We are not yet at the stage of implementation, unfortunately, but we have already achieved results comparable to those offered by materials produced by large corporations.
Will the project help increase the competitiveness of the Polish economy?
Absolutely. We will provide innovative solutions that the economy needs. We will thus increase its international competitiveness. The results of the research will not be shelved but used to produce new, highly advanced materials and technology.
More than 30 academics, engineers, technicians and Ph.D. and undergraduate students are involved in the project—a total of 60-odd professionals headed by Prof. Leszek Jaroszewicz. The project has been running since 2008 and is scheduled for completion in mid-June 2013. It will cost around zl.25 million, of which zl.21 million is co-financing obtained under the European Union’s Innovative Economy Operational Program.