According to reports, the frequency range of terahertz is between microwave and infrared, and it can easily pass through the three-dimensional or four-dimensional structures of macromolecules such as human skin, plastic and clothes, but it is much safer than X-rays because of its low energy.
In addition, because the terahertz spectrum of substances contains rich physical and chemical information, scientists have been hoping to use terahertz laser to distinguish different chemical raw materials, which has great scientific value and broad application prospects in environmental monitoring, medical diagnosis, broadband mobile communication, satellite communication and military radar. However, because the absorption peaks of different substances are at different frequencies in terahertz, it is necessary to use terahertz laser with wide frequency to effectively detect the content of substances.
In the past, there were only two ways to adjust the lasing wavelength of the laser: one was to change the length of the light-emitting cavity or change the temperature of the cavity. In terms that most people can understand, changing the length of the bell cavity is like pressing the strings with your fingers to change the length of the strings while playing the guitar, while changing the temperature of the cavity is like changing the tension of the guitar strings.
Second, changing the pitch means changing the diameter and width of the guitar string. The mechanism of terahertz quantum cascade laser developed by Professor Hu Qing's research group is just like changing the width of guitar strings. The wider the string, the lower the tone, the lower the frequency, the narrower the string, the higher the tone and the higher the frequency. This is a major breakthrough in laser technology research and has a wide range of potential application prospects. When the technology is mature, it can help airport security personnel to easily distinguish whether the luggage contains explosives, psychedelic drugs or painkillers, and many other new scientific and technological fields will also be developed.