An elegant modification doubles the range of low-noise 'white lasers' in a single fiber
Supercontinuum light sources—often called "white lasers" because they emit a broad, continuous rainbow of colors—are essential tools for everything from advanced medical imaging to environmental gas detection. However, researchers have historically faced a frustrating trade-off: A broad spectrum comes at the expense of high fluctuations, which has effectively limited their use.
A research team at DTU Electro has discovered a novel method to significantly enhance the performance of low-noise supercontinuum lasers, known as "white lasers," without compromising their stability. These lasers emit a broad spectrum of colors, making them invaluable for various applications, including advanced medical imaging, environmental gas detection, and spectroscopy.
Traditionally, increasing the spectral width has led to heightened noise levels, limiting their utility. The DTU team's innovative approach, dubbed thermal dispersion engineering, involves heating a small section of a single optical fiber, subtly altering its internal properties to compress light pulses. This modification results in shorter, more intense pulses that generate a broader spectral range while maintaining exceptionally low noise levels.
By achieving a spectral range spanning from 0.86 to 2.90 micrometers, the team has essentially doubled the previous range of similar low-noise systems. This technological breakthrough offers numerous advantages in fields that demand precision and speed. In medical imaging, steadier light can lead to clearer images and reduced scanning times.
In environmental gas sensing, the source enables faster detection of trace amounts of pollutants or greenhouse gases. Moreover, the extended coverage into the infrared spectrum opens up new possibilities for spectroscopic and sensing applications, as many molecules exhibit distinctive optical signatures in this wavelength range.
The researchers emphasize that the advance is not only about achieving record-breaking performance but also about demonstrating an elegant and practical method that could be applied to other wavelengths and fiber systems. Postdoc and first author Andrea Arduin highlights the significance of the findings, stating that keeping noise low directly improves the sensitivity of the sources, making them more useful in practical applications.
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