Short pulse lasers in the form of chips use the so-called mode coupling principle

Nowadays, lasers that emit extremely short flashes can be found in many research laboratories, but they usually fill the entire room. Physicists have now successfully reduced this laser to the size of a computer chip. As they reported in the journal Science, their research can lay the foundation for extremely compact detectors.

A team led by Qiushi Guo from the California Institute of Technology in Pasadena has constructed their prototype semiconductor for short pulse lasers based on gallium arsenide, which is used to generate laser beams. They combined it with a crystal of another compound called lithium niobate, which is used as a conductor for light waves. Researchers arranged these two components on the basis of silicon and silicon dioxide to produce laser chips with a size of only a few millimeters.

Like other short pulse lasers, the new micro laser uses the so-called mode coupling principle: the light waves in the laser match each other in a mutually amplified manner, resulting in extremely short light pulses. Researchers successfully achieved this by applying high-frequency electric fields adapted to laser pulses. Previously, larger short pulse lasers also used this principle. But in the new laser, they cleverly arranged tiny waveguides so that they could keep the laser correspondingly small.

Trillionths of a second of short infrared flash
In testing, the prototype emitted short flashes of less than five picoseconds - millionths of a second infrared light. Their wavelength was 1065 nanometers and they repeated about 10 billion times per second. When doing so, the maximum power of the laser is half a watt, which is 500 times that of a traditional laser pen.

In the future, micro lasers can pave the way for small detectors, such as detecting bacteria and viruses in smartphones. They reflect the incident laser in a unique way, so they can be detected using highly sensitive sensors. Other applications lie in chips that use light to process digital data, making them faster than other systems. Even atomic clock lasers can be used in chip form. These can achieve accurate navigation without GPS signal, "Guo said. Considering these applications, researchers now hope not only to further increase the power of short pulse lasers, but also to make the optical pulses shorter - as low as a few femtoseconds.

Source: Laser Network