image: Figure 1 | Characteristics of TBAY and ABCYSM glass and fiber. a, Transmittance spectrum before and after immersing ultrapure water experiment and calculated core attenuation curve. b, The differential thermal analysis curves of TBAY and ABCYSM glass. c, The microscope image of the TBAY fiber sample. d, Calculated dispersion curves for different core diameters of TBAY fibers.
Credit: Zhenrui Li et al.
Ultrafast laser sources in the mid-infrared (MIR) spectrum are vital for many applications, from detecting trace gases in the atmosphere to advanced medical diagnostics. However, pushing fiber laser technology into the challenging 4−5 μm wavelength range has been hampered by a significant roadblock: the very materials used to generate this light have been bulky, fragile, and inefficient.
For years, researchers have relied on fluoroindate (InF3) fibers, which require lengths of several meters to produce the desired nonlinear optical effects. These meter-scale systems are confined to specialized laboratories due to their size and poor chemical and thermal stability, making them impractical for real-world applications.
In a new paper published in Light: Science & Applications, the Advanced Laser Lab of the College of Physics and Optoelectronic Engineering at Harbin Engineering University, together with Professor Xie Guoqiang's team from Shanghai Jiao Tong University and Professor Liu Yichun's team from Northeast Normal University, have engineered a groundbreaking solution. They developed a novel fluorotellurite glass, named TBAY, which possesses a nonlinear efficiency an order of magnitude higher than previous materials.
This high efficiency allows for a radical miniaturization of the core component. The team demonstrated the generation of tunable, ultrafast pulses centered at 4.6 μm using a TBAY fiber just 13 centimeters long—more than 100 times shorter than existing systems. By slightly altering the fiber's core diameter, they could also generate a different type of light, a dispersive wave, at 4177 nm in a fiber under 10 centimeters.
The scientists summarize the significance of their new material:
“For years, the sheer size and fragility of mid-infrared laser systems have confined them to the lab. Our new TBAY fiber shatters that barrier. Its unique combination of high nonlinearity and excellent thermal and chemical stability allows us to achieve in centimeters what previously took meters, paving the way for compact, robust devices that can be taken into the field.”
Beyond its compact size, the TBAY fiber is also remarkably stable. It can withstand higher temperatures and is resistant to environmental humidity, issues that have plagued its predecessors. This robustness is critical for developing reliable, long-lasting laser systems for industrial and medical use.
“This work is a foundational step,” the scientists forecast. “By creating a better, more practical platform for generating this crucial light, we are enabling the next generation of tools for scientific discovery and technological innovation. We envision portable devices for real-time pollution monitoring, more precise surgical lasers, and new imaging techniques that were previously impossible.”
Journal
Light Science & Applications
Article Title
Generation of tunable Raman soliton and dispersive wave beyond 4 μm in centimeter-length fluorotellurite fibers