Scientists from the Lebedev Institute in collaboration with scientists from Cambridge in the framework of the European project received a blue laser picosecond pulse. These results open up new perspectives, not only in terms of scientific research, such as "photographs" of the movement of elementary particles, but also expand the use of laser technology, such as the creation of new data storage exceeding the capacity Blue Ray discs.
- Violet laser
Laser — a generator of electromagnetic waves in the visible range, that is the source of light. The light of this generator has unique properties: monochromatic (all radiation within a narrow range of wavelengths), and single-minded focus (radiation does not dissipate). Modern science uses lasers to create a gas, liquid, chemical reaction. Nevertheless, the most widely used semiconductor is based on a special pump mechanism. This year, the semiconductor lasers is 50 years old. During this time, passing from the stage of scientific discovery to widespread use, they are firmly entrenched in our lives. But even after so many years of research are still poorly understood niche violet lasers, which are based on gallium nitride (GaN) — the most promising material in electronics. The difficulty of their study is the heavy processing factory. Good examples began to appear recently in Japan.
Objective of the European project, which brings together scientists from Lebedev Physics Institute and the University of Cambridge, was the study of pulsed mode lasers in the blue / violet range. Japanese companies (Sony, Sharp, and others) have excelled in the study of continuous radiation of such lasers. Based on their research has already established technical devices, eg drive blu-ray. Pulsed regimes of generation of light in the violet range by semiconductor region remain poorly understood.
"The samples for the study, we used the lasers used in the blu-ray drives for computers, modified by ion beams using existing equipment at Cambridge University. The modifications, together with the introduction of the laser resonator managed acquisitions, allowed very much change the dynamics of the laser, translate it from continuous mode to pulse"- Says the results of one of the members and leaders of the project, leading researcher of the Physics Institute, Doctor of Physical and Mathematical Sciences Pyotr Vasilyev.
The resulting lasers studied at FIAN on the equipment, which allows to measure the pulses of picosecond (10-12c) and a femtosecond (10-15c) precision. To register these pulses using ultrafast electron-optical camera. This technique is associated with the photoelectron registration, was originally developed at the Lebedev Institute.
The main problem of the research is that the gallium nitride, which is the basis of these lasers, heavy processing. It mass defect, it also degrades quickly in the air, that is, investigated lasers have a short "shelf life", which also limits their time and research.
"We were able to get only picosecond pulses, while hoping for a femtosecond. However, these results have allowed to exceed the parameters of the Japanese laboratory Sony. According to their publications, with the additional use of lenses, lenses, diffraction gratings, as well as an external cavity, they were able to generate pulses of magnitude in units of picoseconds. And we do not use any external components and thus result in 1.4 picoseconds"- Comments Vasiliev.
Ongoing studies are of great value not only from a scientific point of view, but also for applications in biology and medicine. For example, the microscopic scale of the laser allow for compact appliances, mobile and easy to use, and the short pulse duration — to investigate and act on the body’s cells without destroying them.