[RESEARCH HIGHLIGHTS]


| RESEARCH HIGHLIGHTS |


The widely tunable all-fiber laser developed by


researchers at A*STAR can produce infrared laser beams at an unprecedented range of wavelengths. The compact, inexpensive design could have multiple applications in medical and military fields.


Lasers:


TUNING INTO MORE COMPACT LASER DESIGNS


A LASER DEVELOPED AT A*STAR CAN PRODUCE INFRARED BEAMS OVER AN UNPRECEDENTED RANGE OF WAVELENGTHS


A*STAR scientists have developed a unique fast-pulsing fiber laser that has the widest wavelength output to date1. This type of laser could replace several fixed-wavelength lasers and form the basis of compact devices useful for a range of medical and military applications. The team developed an all-fiber laser,


constructed similarly to a fiber-optic cable. The key component is a glass tube, whose core is doped with atoms that act as a gain medium — a material from which energy is transferred to boost the output power of the laser — through


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which light particles, or photons, travel. The doping atoms are selected according to the specific wavelengths of light that they will absorb, store and then release, creating an efficient, controllable output beam. “To date, most tunable all-fiber pulsed


lasers achieve a maximum tuning range of about 50 nanometers,” says Xia Yu from the A*STAR Singapore Institute of Manu- facturing Technology, who worked on the project with her team and her collaborator Qijie Wang from Nanyang Technological


University. “We have achieved a widely tunable laser in the mid-infrared wavelength band, with a range of 136 nanometers (from 1,842 to 1,978 nanometers). We used thulium as the doping atom; this generates a laser that operates in the eye-safe range, meaning it could have medical and military applications.” The researchers combined two techniques


to create their laser and ensure the output was tunable. They used nonlinear polarization evolution, a filtering effect that picks out pulses of light at the desired wavelength and


A*STAR RESEARCH 15


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