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Researchers in Australia have found a way to manipulate laser light at a fraction of the cost of current technology.

The discovery, published in , could help drive down costs in industries as diverse as telecommunications, medical diagnostics and consumer optoelectronics.

The research team, led by from the and , has used inexpensive crystals, known as perovskites, to make Faraday rotators. These manipulate light in a range of devices across industry and science by altering a fundamental property of light 鈥� its polarisation. This gives scientists and engineers the ability to stabilise, block or steer light on demand.

Faraday rotators are used at the source of broadband and other communication technologies, blocking reflected light that would otherwise destabilise lasers and amplifiers. They are used in optical switches and fibre-optic sensors as well.

Dr Lakhwani said: 鈥淭he global optical switches market alone is worth more than $US4.5 billion and is growing. The major competitive advantage perovskites have over聽current Faraday isolators is the low cost of material and ease of processing that聽would allow for scalability.鈥�

To date, the industry standard for Faraday rotators has been terbium-based garnets. Dr Lakhwani and colleagues at the have used lead-halide perovskites, which could prove a less expensive alternative.

Dr Lakhwani said: 鈥淒evelopment聽and uptake of our technology could be aided by the excellent positioning of Australia聽within the Asia-Pacific region, which is growing rapidly聽due to increasing investments in its high-speed communication infrastructure.鈥�

Adapting perovskites

The lead-halide perovskites used by the Lakhwani group are a class of materials that have been gaining a lot of traction in the scientific community, thanks to a combination of excellent optical properties and low production costs.

鈥淚nterest in perovskites really started with solar cells,鈥� said , a postdoctoral researcher leading the project in the .

鈥淭hey are efficient and much less expensive than traditional silicon cells, which are made using a costly process known as the . Now, we鈥檙e looking at another application, Faraday rotation, where the commercial standards are also made using the Cz method. Just like in solar cells, it seems like perovskites might be able to compete here as well.鈥�

In this paper, the team shows that the performance of perovskites can rival that of commercial standards for certain colours within the visible spectrum.

Collaboration is key

鈥淎s part of the聽聽(ACEx), we benefitted from the exchange of ideas through this high-calibre centre,鈥� Dr Lakhwani said. Collaborators included the ACEx groups of聽听补苍诲听, as well as the聽聽group at UNSW. Professor Ho-Baillie has since joined the University of Sydney as the聽.

鈥淲e鈥檝e been looking into Faraday rotation for quite some time,鈥� Dr Lakhwani said. 鈥淚t鈥檚 very difficult to find solution-processed materials that rotate light polarisation effectively. Based on their structure, we were hoping that perovskites would be good, but they really surpassed our expectations.鈥�

Looking ahead, the search for other perovskite materials should be aided by modelling.

鈥淔or most materials, the classical theory used to predict Faraday rotation performs very poorly,鈥� said聽,聽a postdoctoral researcher in the Widmer-Cooper group at the University of Sydney. 鈥淗owever, for perovskites the agreement is surprisingly good, so we hope聽that this will allow us to create even better crystals.鈥�

The team has also performed thermal simulations to understand how a real device would function. However, there is still work to be done to make commercial application a reality.

鈥淲e plan on continuing to improve the crystal transparency and growth reproducibility,鈥� said聽, from UNSW. 鈥淗owever, we鈥檙e very happy with the initial progress and are optimistic for the future.鈥�

Declaration

This work was supported by the .