Scientists from Université Laval in Canada have developed the first fiber laser that can generate femtosecond pulses in the visible range of the electromagnetic spectrum. This laser that can generate ultrashort, bright visible wavelength pulses can be widely used in biomedical, material processing and other fields.
The devices that typically generate visible femtosecond pulses are complex and inefficient, while fiber lasers have the advantages of stability, reliability, small footprint, high efficiency, low cost, and high brightness, making them a very promising alternative solution. But so far, this type of laser has not been able to directly generate visible light pulses with a duration in the femtosecond (10-15 seconds) range.
The head of the research team, Ruir Varley, said that they have developed the first femtosecond fiber laser that can work in the visible light range. The laser is based on Lanthanide doped fluoride fiber, which can emit 635nm red light, and achieve a compressed pulse with a duration of 168 femtoseconds, a peak power of 0.73kW, and a repetition rate of 137 MHz. Moreover, they use commercial blue laser diodes as energy sources in their equipment, making the overall design more robust, compact, and cost-effective.
The research team pointed out that if higher energy and power can be obtained in the near future, it can be widely applied in many fields. Potential applications include high-precision, high-quality tissue ablation and Two-photon excitation microscopy. In addition, femtosecond laser pulses can also perform cold ablation during material processing, which does not produce thermal effects, making cutting cleaner than using longer pulses.
Next, researchers plan to improve this technology to make the device completely monolithic, which means that each fiber optic component will be directly interconnected, reducing the optical loss of the device, improving efficiency, and further improving the reliability, compactness, and robustness of the laser. They are also studying different ways to increase laser pulse energy, pulse duration, and average power.