SLD is a non-coherent light source that uses amplified spontaneous radiation. It combines the high power of a laser and the broad spectral characteristics of an LED. Ideal source for non-coherent optical systems such as optical coherence tomography (OCT). OCT technology is a biomedical imaging technology developed in the 1990s with many advantages such as high resolution, non-contact, and no radiation damage. It has important applications in clinical diagnosis of ophthalmology, dentistry, and dermatology. This is another major technological breakthrough after X-CT and MRI medical imaging technology. The development of the OCT system is closely related to the light source used, and its application and upgrading depend strongly on the development level of the core light source. At present, although OCT technology has been recognized by the public, some domestic and foreign hospitals have set up special OCT imaging departments, but the great advantages of OCT technology have not yet been realized, because they encountered two major bottlenecks in their development: (1) imaging resolution The rate is low; (2) The imaging depth needs to be improved. Therefore, the requirements for the broad-spectrum light source used in the OCT system are: (1) the preparation of a near-infrared broad-spectrum light source in which high power and wide-spectrum coexist; and (2) the working wavelength of the broad-spectrum light source is extended to the mid-infrared band.
In response to this scientific problem, the Zhang Zizheng team of the Suzhou Institute of Nanotechnology, Chinese Academy of Sciences, and Liu Fengqi and Wang Zhanguo Laboratory of the Institute of Semiconductors of the Chinese Academy of Sciences have used modulation-doped multilayer quantum dot structures to break the mutual constraints of output spectral width and output power in traditional semiconductor wide-spectrum light sources. In the near-infrared band, the laser pointer with high output power> 20 mW and wide-spectrum> 130 nm (as shown in Figure 1) was successfully developed. Then, quantum cascade materials with inter-subband transitions were used. As a gain medium, a wide-spectrum light source and optical amplifier monolithic integrated device structure is used to realize the world’s first mid-infrared quantum cascade SLD (see Figure 2) that operates continuously at room temperature. This progress fills the mid-infrared Blanks for semiconductor wide-spectrum light sources that operate continuously in the band at room temperature. These research results have laid the foundation of materials and devices for improving the performance of the current near-infrared OCT system and realizing the mid-infrared OCT system theoretically predicted many years ago.