The researchers transmitted light pulses of 13 fs duration (1 fs = 1 millionth billionth of a second) over one meter distance, with the pulses only stretching to about double of the initial duration. “Currently, no other fiber-based technique is capable of such little distortion”, says Dr. Günter Steinmeyer.
In comparison, using similar fibers of a more conventional make, pulse stretching to more than 50 times the original duration was observed. The novel fibers may be useful in medical applications, e.g., for guiding femtosecond pulses to the patient in a flexible manner. In their advance online section, Nature Photonics reports about this novel type of fiber.
The MBI fiber consists of many glass capillaries and guides the light on a diameter equal to about half the diameter of a human hair. In contrast to conventional hollow fibers, which consist of capillaries of equal diameter, the diameter changes in MBI’s novel fiber (see figure). This can be understood as gluing straws side by side, yielding a tube of straws when the first and the final straw are also glued together. Repeating this procedure with straws of different diameter and fitting the resulting tubes into one another ultimately yields a structure similar to MBI’s fiber. For manufacturing the fiber, the researchers have used 5 such tubes of straws. Referring to the systematic change in capillary diameter, the researchers call such a structure chirped.
Launching ultrashort laser pulses into such a fiber, the chirped structure acts to distribute detrimental resonances over a wide wavelength range, which would otherwise add up at one wavelength if the capillaries had all the same diameter. The fiber was manufactured at Saratov State University in Russia.
The researchers see one particularly interesting medical application of their fiber in photodynamic therapy. For this method, a photosensitizer is accumulated in cancerous cells. Exposing the photosensitizer to light, a substance is formed which causes fatal damage of the tumor cells. Using ultrashort laser pulses rather than continuous light, the selectivity of this therapeutic method could be significantly improved as the photoexcitation could be limited to the immediate vicinity of the focal area, whereas tissue layers immediately above or below the interaction zone would stay unharmed.
So far, however, no fiber was available to guide the required short light pulses to the patient in a flexible way without severe distortions through an endoscope. The chirped fiber structure could also be beneficial for diagnostic applications in biology and medicine, such as in two-photon microscopy, a method that allows for three-dimensional resolution of smallest biological structures at effective suppress.
Significantly more productivity in USP lasers
06.12.2016 | Fraunhofer-Institut für Lasertechnik ILT
Shape matters when light meets atom
05.12.2016 | Centre for Quantum Technologies at the National University of Singapore
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
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07.12.2016 | Health and Medicine
07.12.2016 | Life Sciences
07.12.2016 | Health and Medicine