As the Reuters superluminescent diodes (SLD) is a use of amplified spontaneous emission of incoherent light source which combines the properties of high power lasers and broad spectrum of an LED, while having low temporal coherence and high optical coupling efficiency, It is the ideal source for some incoherent optical systems such as optical coherence tomography (OCT). OCT technology is a biomedical imaging technology developed in the 1990s with high resolution, non-contact, and no radiation damage. It has been used in clinical diagnosis of ophthalmology, dentistry and dermatology. It 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 are still far from being reflected, because they have 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 wide-spectrum light source used in the OCT system are: (1) the preparation of a near-infrared broad-spectrum light source with high power and wide spectrum coexistence; and (2) the operating wavelength of the broad-spectrum light source expanding toward the mid-infrared band.
In response to this scientific problem, Zhang Zikai, a research group of the Suzhou Institute of Nanotechnology, Chinese Academy of Sciences, and Liu Fengqi and Wang Zhanguo, the Institute of Semiconductors of the Chinese Academy of Sciences, cooperated to modulate the doped multi-layer quantum dot structure, breaking the output spectral width and output power of traditional semiconductor broad-spectrum light sources. The relationship has successfully developed a quantum dot SLD with a high output power >20 mW and a broad spectrum >130 nm in the near-infrared region (as shown in Figure 1); then a quantum cascade material with inter-subband transitions is used as the gain. The medium, using a wide-spectrum light source and an optical amplifier monolithically integrated device structure, realizes the world's first mid-infrared quantum cascade SLD (shown in Figure 2) that works continuously at room temperature. This progress fills the mid-infrared band room temperature. A blank for continuous operation of semiconductor broad-spectrum light sources. These research results lay the material and device foundation for improving the performance of the current near-infrared OCT system and realizing the mid-infrared OCT system predicted by theory many years ago.
Fig.1 Schematic diagram, spectrum and PI curve of modulated doped self-organized quantum dot J-shaped waveguide SLD
Fig. 2 Mid-infrared quantum cascade SLD structure and illumination diagram for continuous operation at room temperature
Editor: Yan Zhixiang
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