Recently, a group of researchers from the University of Twente in the Netherlands made a breakthrough in the generation of supercontinuum on ultra-efficient chips. They announced that they had successfully developed an ultra-efficient ultra-continuous white laser chip. This discovery represents "a big step forward in the field of integrated photonics" and can be applied to portable medical imaging devices, chemical sensors and laser radars. Relevant achievements have been published in the journal Advanced Photonics Research.
The light emitted by lasers is usually coherent: their waves are the same in frequency and waveform. This kind of coherence makes it possible to send a narrow beam with very low noise over a very long distance.
But this also means that this kind of laser usually only emits a single wavelength, which will limit its application. In contrast, supercontinuum spectral laser can produce continuous color spectrum, thus showing white.
They are used in 3D imaging devices. However, it has been proved that in order to produce this wide band color, supercontinuum laser has a very high peak power consumption (pulse energy), which is huge and must be stable in the laboratory. This makes them expensive and useless.
The researchers at the University of Twente significantly reduced the required pulse energy by using the so-called symbol alternating dispersion waveguide. This kind of waveguide is designed to control the dispersion of light by alternately widening and shrinking the beam. Compared with the traditional method, this method reduces the required pulse energy by about 1000 times. This method provides a more effective method to generate supercontinuous medium light on the chip, which has many potential applications in medical imaging and laser radar.
Researchers have proposed a scheme to significantly reduce the input energy demand of integrated supercontinuum power generation by several orders of magnitude, which is used for 500-1000 nm bandwidth power generation. By means of symbol alternating dispersion in CMOS compatible silicon nitride waveguide, the efficiency is increased by 2800 times.
The research shows that the energy requirement of the pulse with large bandwidth supercontinuum spectrum generated at high spectral power (such as 1/e level) is reduced from nanojoules to 6 pJ. The reduction of pulse energy requirements enables the chip to integrate laser sources (such as mode-locked isomeric or hybrid integrated diode lasers), thus realizing a fully integrated on-chip high-bandwidth supercontinuum dielectric source.
Source: OFweek
