Three researchers in basic sciences have just made history with a completely new type of mode-locked laser. This groundbreaking technology is poised to transform photonics with its exceptional tunable pulse duration and ultranarrow bandwidth. This innovative laser, equipped with a long-cavity structure, allows obtaining a repetition frequency lower than one megahertz. The tuning range for pulse-width covers from 481 picoseconds to 1.38 nanoseconds. This achievement establishes a new world record, representing the widest reported tuning range ever achieved.
This laser development is indeed as remarkable. It has a series of cutting edge technologies, including a special filtering mechanism that employs two filters composed of fiber Bragg gratings. We have found that these filters are a very poor approximation of single narrow band wavelength bands. This precision pushes the laser’s exceptional performance to even greater heights. By applying mechanical stress to one of the gratings, the sensor’s capabilities are made even more robust.
Innovative Design and Mechanisms
This laser adopts a novel design based on all-SWCNTs as saturable absorbers (SAs). These pieces are an integral part of the laser’s function. These carbon nanotubes provide an ultrafast recovery time on the femtosecond scale. They are relatively cheap to produce. They are particularly good for producing stable pulse durations in the femtosecond to picosecond range. That capability uniquely positions them as a key building block for this complex laser system.
Mechanical strain applied to the grating surface further optimizes the unique filter design. This allows for very fine tunings of the pulse duration. This long-cavity structure of the laser increases its efficiency and performance. This design produces a very dense source of light, making it suitable for many different applications.
“We have successfully developed an ultranarrow bandwidth mode-locked laser with a widely tunable pulse duration using a novel filtering mechanism and a single-wall carbon nanotube SA.” – Weixi Li
Applications and Impact
The impact of this long-pulse advanced laser technology reaches far beyond defense applications, to include materials processing and photonics research. Creative design was the source of the laser, says Robert Day, chair of Professor Chengbo Mou. It is an equally important role as a tool for practical application, though.
“We have not only designed a simple, flexible, and tunable scheme for narrow-bandwidth mode-locked lasers, but have also developed an ideal light source with robust output for important fields such as cutting of single-crystal diamonds and laser stealth cutting of semiconductor wafers.” – Professor Chengbo Mou
The flexibility of this laser allows it to adapt to different operational requirements, making it a valuable asset in industries that demand high precision and control over laser properties. Furthermore, its reduced power consumption is well-timed towards the shift in demand for energy-efficient technologies.
Future Prospects
Until then, researchers are hard at work investigating everything that this new mode-locked laser makes possible. The opportunity for game-changing developments in laser technology is huge. These exciting new possibilities are largely due to the unprecedented wide tunable range and ultranarrow bandwidth. Suddenly, we could address uses that weren’t possible to reach with conventional lasers.
This exciting innovation amplifies great technologies that are already out there. It unleashes an exciting new wave of applications that will flourish on the back of better laser performance. The ongoing development and refinement of this laser technology underscore the importance of interdisciplinary research in driving advancements in photonics.