The superluminescent light emitting tube is an incoherent light source that utilizes amplified spontaneous emission. It combines the high power of the laser and the broad spectral characteristics of the LED. At the same time, it has weak time coherence and high fiber coupling efficiency. It is a non-coherent optical system ( For example, OCT is an ideal light source for optical coherence tomography (OCT). OCT technology is a kind of biomedical imaging technology developed in the 1990s with many advantages such as high resolution, non-contact, no radiation damage, etc. It has been applied in the clinical diagnosis of ophthalmology, dentistry and dermatology. It is another major technological breakthrough after X-CT and MRI medical imaging technology. The development of OCT system is closely related to the light source used, and its application is strongly upgraded. Land depends on the level of development of the core light source. Although OCT technology has been recognized by the public, some domestic and foreign hospitals have set up specialized OCT imaging departments, but the great advantages of OCT technology are far from being reflected because of the two The main bottlenecks are: (1) Lower imaging resolution; (2) Depth of imaging needs to be improved. The appeal of the wide-spectrum light source used in the OCT system is: (1) Preparation of a broad spectrum near infrared light source with a broad spectrum of power coexist; (2) the broad band light source to expand the operating wavelength in the infrared band.
In response to this scientific problem, the Zhang Ziji research group of the Suzhou Nanotechnology Institute of the Chinese Academy of Sciences and the Liu Fengqi and Wang Zhanguo Institute of Semiconductors of the Chinese Academy of Sciences used the modulation-doped multi-layer quantum dot structure to break the output spectrum width and output power of conventional semiconductor wide-spectrum light sources. We have successfully developed a quantum dot SLD with a high output power >20 mW in the near-infrared band and a wide spectrum >130 nm (shown in Figure 1); this is followed by the use of quantum cascade materials with inter-subband transitions as gains. Medium, using a wide-spectrum light source and optical amplifier monolithically integrated device structure, the world's first mid-infrared quantum cascade SLD (shown in Figure 2) operating at room temperature, this progress filled the mid-infrared band room temperature Continuous blanking of semiconductor wide-spectrum light sources. These research results have laid a foundation for materials and devices for the purpose of improving the performance of current near-infrared OCT systems.
Fig.1 Schematic diagram of modulation doped self-organizing quantum dot J-type waveguide SLD, spectrum and P-I curve
Fig.2 Structure and luminescence diagram of mid-infrared quantum cascade SLDs working continuously at room temperature
The above results were published in Light: Science & Applications 7, 17170 (2018). This work was funded by the National Natural Science Foundation of China, the National Key R&D Program and the Youth 1000 Program.
