Research progress of laser

Scientists at the University of Texas have developed the most powerful operating laser in the world. This laser generates 2000 times more energy per trillionth of a second than all power plants in the United States, and its output power exceeds 1 watt-equivalent to 10/5 watt. This laser was first started by 1996. Martinez said that he hopes his project can break this record in 2008, that is, let the laser power reach between 1.3 and 1.5. McAll Martinez, the head of the super laser project, said: "We can make materials enter an extreme state, which is invisible on the earth. The phenomenon we intend to observe in Texas is equivalent to entering space to observe an exploding star. "

Laser "grabs" carbon nanotubes and makes them move.

Scientists from new york University in Illinois and researchers from an optical company have experimented with a technique called "optical trap" in an attempt to manipulate carbon nanotubes more easily. Optical capture technology is to use the ability of laser to capture tiny particles, and make tiny particles move with the laser when moving the laser beam. Because laser can capture tiny particles, it will "clamp" tiny particles like tweezers when it moves. Scientists call this phenomenon "laser tweezers". In 20 13 years, biologists can clamp a single cell with laser tweezers. For example, a single red blood cell isolated from blood is used to study sickle cell anemia or malaria treatment. Laser tweezers can "clamp" tiny particles because the central intensity of the laser beam is greater than the edge intensity, so when the laser beam irradiates tiny particles, the light refracted from the center is more than the forward light.

When the refracted light gains an outward impulse, the reaction force on the particles makes the impulse point to the center of the laser beam, so the particles are always attracted to the center of the laser beam. If the particle is very small, the attraction or friction is very small, and when the laser beam moves, the particle will also move with it.

The diameter of blood cells moved by laser tweezers is several microns, but it will be a lot of trouble to move carbon nanotubes with a diameter of only 2 ~ 20 nanometers before 20 13. Therefore, moving a large number of carbon nanotubes to a certain position with a single laser tweezers may be as laborious as using an atomic force microscope.

To this end, scientists use a liquid crystal laser separator to divide the laser beam into 200 small laser beams that can be controlled independently. Researchers can control these laser beams to form triangles, quadrilaterals, pentagons and hexagons, thus moving a large number of nanotube groups and positioning them on the surface of microscope slides to achieve the purpose of moving carbon nanotubes.

The success of light capture technology was praised by Alex Thurtle, a nanotube expert and physicist at the University of California. He said that since there is no reliable technology to manipulate a large number of nanotubes in 20 13 years, this new optical trapping technology may be applied to industry. The transmission speed of the demonstration laser beam video experiment by NASA reaches more than 1000 megabyte per second.

April 20 14, NASA's Jet Propulsion Laboratory successfully completed an optical technology demonstration and verification experiment. Its specific plan "Optical Payload for Laser Communication Science" (OPALS) can increase the communication rate of future NASA spacecraft by 10 to 100 times. This is the first time that NASA has tested optical communication in the orbital laboratory.

In space missions, the scientific instruments used increasingly need higher communication rates to send the collected data back to Earth, or to support high data rate applications, such as high-definition video streaming. Optical communication, also known as "laser communication", is a new technology that uses laser beams to transmit data. It can provide a higher data rate, which exceeds the currently adopted radio frequency (RF) transmission speed, and has the advantage that the band operation is not regulated by the current Federal Communications Commission.

Matt Abrahamsen, the project manager, said that optical communication could change the rules of the game. Many deep space exploration missions are carrying out communication tasks of 200 to 400 kilobits per second. OPALS will display a transmission speed of up to 50 megabits per second, and the future deep space optical communication system will even provide a transmission speed of more than 1000 megabits per second. 2065438+200565438+1On October 27th, New Scientist reported that scientists captured the image of laser flying in the air for the first time with an ultra-high-speed camera that can detect a single photon at 20 billion frames per second. Within 10 minute, the researchers recorded 2 million laser pulses generated when photons collided with air. This technology can be used to patrol the corners of the environment, display invisible objects on the screen, and can also be used in places where accurate time information needs to be measured.

"This is the first time we have seen light passing by," said Gariepy, the lead researcher at Heriothwater University. Under normal circumstances, scientists can only see light through the reflection of objects. It is more difficult to see the laser emitted by the laser, because the photons move in the focused beam and in the same direction.

The camera was developed by the University of Edinburgh, and its photosensitive module consists of a single photon photosensitive pixel array. These pixels have two characteristics: one is the ability to be sensitive to a single photon-the sensitivity of each pixel is about 10 times that of the human eye; The second is their speed-each pixel is activated in only 67 picoseconds (one trillionth of a second), which is 65.438+billion times faster than blinking. "These characteristics enable us to achieve' flying imaging'." Rich said that when light flies in the air and scatters from objects, this imaging method can even photograph the light itself. Ultrafast laser

Ultrafast laser is a laser developed by Taia Laser based on SESAM mode-locking technology, Amberpico series picosecond lasers and Amberfemto series femtosecond lasers. Amberpico series picosecond lasers have ultra-short pulse width (less than 15ps), high single pulse energy (maximum single pulse energy is 30mJ), high repetition rate (above 1kHz) and reliable excellent output performance. Amberpico series femtosecond lasers have a pulse width of less than 200fs, and the repetition frequency can be selected from 1 Hz to 100 kHz. The high-efficiency output of light with the second, third and even fourth frequencies can be realized. The wavelength range covers infrared, green and ultraviolet, and the shortest wavelength can reach 266/263nm.

Picosecond continuous mode-locked laser

Picosecond continuous mode-locked laser is a kind of "ultrashort" pulse continuous mode-locked laser whose pulse width is compressed to ps order (10- 12s). According to the pumping mode, it can be divided into lamp-pumped picosecond continuous mode-locked laser and semiconductor-pumped picosecond continuous mode-locked laser. According to the mode-locked mode, it can be divided into semiconductor saturable absorber continuous mode-locked picosecond laser and dye continuous mode-locked picosecond laser. According to the laser medium, it can be divided into solid picosecond continuous mode-locked laser and fiber picosecond continuous mode-locked laser. Generally, semiconductor saturable absorption mirror is used as mode-locked device, and LD pumps picosecond continuous mode-locked laser. Generally, the so-called semiconductor saturable absorber is directly grown on the semiconductor Bragg reflector by epitaxial method, so it is called saturable semiconductor Bragg reflector (SBR) or semiconductor saturable absorber (SESAM).