Overview of the latest developments in the field of laser technology

At present, the application of laser technology has entered our daily life and has become an ideal tool for material processing. At the same time, in the field of laser technology and key devices, researchers have not stopped. Let everyone follow in the footsteps of the editor and learn about the latest developments.

1. Realize the widest spectrum dark soliton pulse output

Ultrashort pulse fiber laser has the characteristics of easy operation, compact structure, stable performance and low cost. It is widely used in high-speed optical communications, optical sensing, optical frequency comb, lidar, spectral analysis, military and other related fields. One of the research hotspots in the field. Young teachers such as Liu Wenjun and Lei Ming of the School of Science of Beijing University of Posts and Telecommunications have theoretically analyzed the dynamic behavior of dark soliton pulse generation in response to the limitations of dark soliton pulse generation technology, and experimentally achieved the widest spectrum dark soliton pulse output. Based on the nonlinear Schrodinger equation and the complex Ginzburg-Landau equation, the transmission characteristics of the dark soliton pulse in the fiber laser are studied by changing the nonlinear parameters of the fiber. A method to weaken the interaction of the dark soliton pulse is proposed theoretically, and it is realized experimentally. The stable output of the dark soliton pulse in the fiber laser. After theoretical calculations, the fiber laser cavity dispersion and nonlinear parameters were further optimized, and the widest spectrum dark soliton pulse fiber laser was successfully developed, and the shortest pulse width of 67 was achieved through the collaborative optimization of the tapered fiber and the saturable absorption material. Hybrid mode-locked fiber laser output of fs. The research group also used it for all-fiber laser mode locking, further achieving a mode-locked pulsed laser output with a pulse width of 246 fs. It is known that this is the shortest pulse width report produced by a transition metal sulfide all-fiber mode-locked laser so far.

2. The efficiency of the miniature ultraviolet band femtosecond pulse tripler is increased by three times

Researchers at the University of Warsaw have developed a miniature frequency tripler with a conversion efficiency of more than 30%. A single laser beam is focused by cascading a second-order frequency doubler to generate a 246fs ultraviolet pulse. Through the three-dimensional modeling of the propagation process of the focused broadband light field in the nonlinear and birefringent medium, the design of this ultra-small and high-efficiency inverter can be realized.

Although advanced laser technology has been able to cover a wider spectral region, it is still difficult to realize the ultraviolet band laser of about 300nm, especially the production of high-intensity short-pulse ultraviolet laser is even more difficult. Usually, scientists convert near-infrared laser pulses into ultraviolet laser pulses through nonlinear frequency converters. But the adjustment of the frequency converter is extremely complicated, and its conversion efficiency is only about 10%.

The miniature UV-band femtosecond pulse tripler developed by the University of Warsaw makes it possible to manufacture deep UV-band lasers.

3. The world record of laser monochromaticity

German and American scientists have jointly created a laser with a spectral line width of only 10 millihertz (1 millihertz is 0.001 hertz), setting a new world record for laser monochromaticity. The press release issued by the German Federal Institute of Physics and Technology stated that this is the laser that has so far been the closest to ideal monochromaticity. Using it to measure atomic frequencies can make photonic clocks more accurate, and is also useful for research in spectroscopy and radio astronomy.

The line width of ordinary lasers is usually several kilohertz to several million hertz, which is not suitable for experiments with particularly high precision requirements. Scientists from the Federal Institute of Physics and Technology of Germany and the United States Institute of Experimental Astrophysics collaborated to create two laser beams with a wavelength of about 1.5 microns. The comparison confirms that the line width is 10 millihertz. The two lasers are very stable. All the light waves that make up the laser are very similar, and the oscillation steps are highly consistent. They can maintain synchronization for at least 11 seconds at 194 trillion times per second. During this time, the laser can travel 3.3 million kilometers, which is equivalent to nearly 10 times the distance from the earth to the moon.

4. Integrated 100kHz narrow linewidth laser light source

Recently, the “Integrated 100kHz narrow linewidth laser light source” (project number: 2013AA014202) in the field of information technology under the National 863 Program undertaken by Fujian Construction has passed the expert acceptance organized by the High Technology Research and Development Center of the Ministry of Science and Technology.

This subject is oriented to the special needs of 400Gb/s high-speed coherent optical communication systems for narrow linewidth lasers. It has carried out research on semiconductor gain material growth laser gain chip preparation, fiber grating design and semiconductor laser structure packaging, etc., and developed a domestically based dual The FBG external cavity narrow-linewidth semiconductor laser with segment gain chip realizes small-scale integration, low power consumption, low cost, and highly stable narrow-linewidth laser output.

Five, storage ring free electron laser

Researchers from the Shanghai Institute of Applied Physics, Chinese Academy of Sciences recently proposed a new mechanism for generating high-brightness, fully coherent radiation based on a storage ring light source. Studies have shown that this operating mechanism can make full use of the characteristics of the storage ring electron beam, and can realize the generation of femtosecond high peak brightness X-ray pulses through simple device modification, thereby greatly enhancing the performance of the storage ring light source.

The third-generation synchrotron radiation source based on the storage ring has become a major scientific platform supporting basic and applied research in physics, chemistry, materials, medicine, and life sciences. The third-generation synchrotron radiation source has many advantages, such as high average brightness, stable pulse energy, and simultaneous support for multi-user operation. However, limited by the principle, it also has shortcomings such as low peak brightness, long pulse length and no longitudinal coherence. In order to overcome these shortcomings of the storage ring light source, people are developing X-ray free electron lasers. At the same time, with the development of diffraction-limited storage ring light sources in recent years, people have begun to explore the feasibility of generating fully coherent free electron lasers based on the storage ring, and some new solutions have been proposed.