A Canadian team has developed the first visible femtosecond fiber laser

Researchers at Laval University in Canada have announced the development of the first visible femtosecond fiber laser, which is capable of producing bright femtosecond pulses in the visible light band and can be used in materials processing and a variety of biomedical applications.

Previously, it was not possible to produce visible pulses with a duration in the femtosecond (10-15 seconds) range directly using fiber lasers, as this often required complex and inherently inefficient setups.

Their new laser combines lanthanide doped fluoride fiber and a commercial blue diode-pumped laser to emit 635nm red light and achieve a compressed pulse with a duration of 168fs, a peak power of 0.73 kW, and a repetition rate of 137MHz. Thanks to the use of a commercial blue laser diode as the pump source, the overall design is more robust, compact and economical and efficient.

"We have achieved an operational demonstration of a femtosecond fiber laser in the visible spectrum, paving the way for new types of reliable, efficient and compact ultrafast lasers," said Rsamal Vallsame, leader of the research team.

According to the researchers, the recent emergence of semiconductor laser sources capable of operating in the blue spectral band is key to the development of such highly efficient visible fiber lasers. They also noted that improvements in the manufacturing process for fluoride fibers were also critical for them to obtain lanthanide doped fibers capable of achieving the properties required for efficient visible fiber lasers.

If it can be configured with higher power and energy in the future, this type of laser is expected to play an efficient role in more applications, including high-precision, high-quality biological tissue ablation and two-photon excitation microscopy. The femtosecond laser pulse is also capable of cold ablation during material processing because it does not produce a thermal effect, so it can achieve a cleaner cutting effect [than a long pulse]."

Next, the researchers hope to improve the technology by making the entire device fully monolithic, meaning that the individual fiber pigtail optics will all be directly connected together. This will reduce the optical loss of the device, increase efficiency, and make the laser more reliable, compact, and robust. In addition, they are currently investigating different ways to increase the laser pulse energy, pulse duration and average power.

Source: OFweek