Technique could bring photonic chips to light

1 min read

Researchers at the University of Southampton have found a way to produce more reliable and robust photonic chips.

Until now, testing and characterising optical chips has been difficult as the light travelling in them is confined in the silicon and therefore cannot be seen or measured. The new method developed by the Southampton team enables the flow of light in photonic chips to be 'seen' for the first time. Called ultra fast photomodulation spectroscopy (UPMS), it uses ultraviolet laser pulses of femtosecond duration to change the refractive index of the silicon in a tiny area on the chip. Project leader Dr Roman Bruck explained: "Monitoring the transmission of the chip while the refractive index is locally changed gives a precise picture of how the light flows through it. "This allows testing of individual optical elements on the chip, a crucial step in the design optimisation to ensure its flawless operation. Because the changes induced by the technique are fully reversible, this testing method is non destructive and after testing, the chip can be used for its intended application." Dr Bruck says the technique is fast, robust and has the potential to be used for industrial testing in the photonics industry.