Sensor technology enables new type of compact fibre laser

An adaption of fibre-optic sensors by researchers from the Institute of Photonics technology at Jinan University in Guangzhou has led to the development of a fibre laser photoacoustic imaging technique that exploits the effects of sound on laser pulses. The technique may have applications in wearable devices, instrumentation and medical diagnostics.

Presenting their research at an optics and laser science conference in Washington DC earlier this week, the team, led by Long Jin, explained how their technique depends on the thermo-elastic effect – temperature changes that occur as a result of elastic strain in optical fibres. According to Jin, this effect is commonly used in military fibre laser applications to detect acoustic waves in the kilohertz frequency range. "But it turns out that they don't work so well for ultrasound waves at the megahertz frequencies used for medical purposes because ultrasound waves typically propagate as spherical waves and have a very limited interaction length with optical fibers," he said. This limits their use in medical imaging, where ultrasound is frequently used. Medical ultrasound machines use piezoelectric detectors, whose sensitivity is rather low.