A laser created by a team at the University of Warsaw generates ultrashort pulses of light, even under extremely difficult external conditions like large temperature gradients of more than 120 degrees Celsius. The process of generating femtosecond laser pulses takes place within a specially selected fiber optic cable.

The lasers used to generate femtosecond pulses – just a few millionths of a billionths of a second – usually require an optic resonator, or precision set of mirrors that is sensitive to external conditions. The femtosecond laser from the UW Faculty of Physics, however, generates pulses in an ytterbium-doped optical fiber. The wavelength of the light emitted is close to a micron (1030 nanometers), which can then be multiplied by generating higher-order harmonics.

Because the optical fiber itself is flexible, laser pulses can be easily led into places inaccessible to traditional laser techniques. Built using commercially available components (a pump semiconductor diode and its driver), the simple design costs just a few thousand euro.

The “spaghetti noodle” laser could be an important element of devices generating terahertz radiation, such as medical equipment and optical coherence tomography used to study soft tissues like the retina.