The Science Island team has made breakthroughs in high pulse energy mid infrared fiber transmission

Recently, the Jiang Haihe Research Group of the Health Institute of the Chinese Academy of Sciences Hefei Institute of Materia Medica made important progress in the research of the high-energy pulsed laser transmission system in the mid infrared band, and designed a 78 μ The 6-hole microstructure anti resonant hollow core fiber (AR-HCF) with a larger core diameter achieved efficient transmission of 2.79 at room temperature for the first time μ M-band high-energy pulse laser. The relevant achievements have been published in the internationally renowned optical top journal Optics and Laser Technology.

Laser medical instruments usually require a flexible catheter to transmit the laser emitted to the patient's treatment site, but traditional mid infrared laser medical instruments mostly use a guide arm to transmit the laser. However, the traditional light guide arm transmission method for laser has many problems, such as complex system structure, low transmission efficiency, and insufficient flexibility. The use of fiber optic transmission can solve the above problems, but the material of solid core fiber has a low laser damage threshold in the mid infrared band, which cannot meet the requirements of 3 μ High energy density optical guidance requirements for m-band erbium laser medical devices. So, the research team designed and researched an AR-HCF alternative light guide arm with a simple structure, high coupling transmission efficiency, large damage threshold, and flexible transmission to transmit laser energy.

The team adopts a design with 78 μ A 6-well microstructure AR-HCF with a larger core diameter of m, efficiently transported for the first time under room temperature conditions at 2.79 μ M-band high-energy pulse laser. Without damaging the optical fiber, the average coupling transmission efficiency of the entire region is 77.3%, and the highest coupling transmission efficiency reaches 85% under high beam quality and small coupling energy. If the air absorption attenuation in the fiber core is deducted, the self transmission efficiency of the fiber optic system with this structure has actually exceeded 90%. The system achieved a maximum pulse laser energy output of 11.78 mJ, with a corresponding energy density threshold of 350J/cm2, far exceeding the required value for soft tissue ablation of living organisms. At the same time, the minimum bending radius of the AR-HCF is 20cm and the corresponding loss can meet the clinical needs of surgeons, and the laser beam quality at the output end of the AR-HCF is better than that at the input end, which has been improved significantly.

Compared to other structures and materials currently used for 2.79 μ Compared to optical fibers with m-wavelength transmission, the 6-hole structure AR-HCF of this silica has stronger mechanical stability, higher damage threshold, lower bending sensitivity, and superior transmission performance compared to traditional light guide arms. This study is 2.79 μ M Cr, Er: YSGG medical solid-state laser has opened up a new way for efficient transmission.

Figure 1. Cross section structure of AR-HCF

Figure 2.2.79 μ M AR-HCF space transmission experimental device

Figure 3. Loss of AR-HCF under different bending radii and bending directions

Source: Hefei Institute of Physical Sciences, Chinese Academy of Sciences