Design of a High-Efficiency Multilayer Dielectric Diffraction Grating with Enhanced Laser Damage Threshold

Duy Thanh Cu; Tien Dat Pham; Vu Tuan Hung Le; Meng Chi Li; Hung Pin Chen; Chien Cheng Kuo

doi:10.3390/nano12121952

Design of a High-Efficiency Multilayer Dielectric Diffraction Grating with Enhanced Laser Damage Threshold

Nanomaterials (Basel). 2022 Jun 7;12(12):1952. doi: 10.3390/nano12121952.

Authors

Duy Thanh Cu¹, Tien Dat Pham¹, Vu Tuan Hung Le², Meng Chi Li³, Hung Pin Chen⁴, Chien Cheng Kuo¹

Affiliations

¹ Department of Optics and Photonics/Thin Film Technology Center, National Central University, 300, Chung Da Rd., Chung Li, Taoyuan 32001, Taiwan.
² Department of Applied Physics, Faculty of Physics and Engineering Physics, Ho Chi Minh City University of Science, 227 Nguyen Van Cu Street, Award 4, District 5, Ho Chi Minh City 748000, Vietnam.
³ Optical Sciences Center/Thin Film Technology Center, National Central University, 300, Chung Da Rd., Chung Li, Taoyuan 32001, Taiwan.
⁴ National Applied Research Laboratories, Taiwan Instrument Research Institute, No. 20. R&D Rd. VI, Hsinchu Science Park, Hsinchu 30076, Taiwan.

Abstract

Diffraction gratings are becoming increasingly widespread in optical applications, notably in lasers. This study presents the work on the characterization and evaluation of Multilayer Dielectric Diffraction Gratings (MDG) based on the finite element method using Comsol MultiPhysics software. The optimal multilayer dielectric diffraction grating structure using a rectangular three-layer structure consisting of an aluminum oxide Al₂O₃ layer sandwiched between two silicon dioxide SiO₂ layers on a multilayer dielectric mirror is simulated. Results show that this MDG for non-polarized lasers at 1064 nm with a significantly enhanced -1st diffraction efficiency of 97.4%, reaching 98.3% for transverse-electric (TE) polarization and 96.3% for transverse-magnetic (TM) polarization. This design is also preferable in terms of the laser damage threshold (LDT) because most of the maximum electric field is spread across the high LDT material SiO₂ for TE polarization and scattered outside the grating for TM polarization. This function allows the system to perform better and be more stable than normal diffraction grating under a high-intensity laser.

Keywords: diffraction efficiency; high laser damage threshold; multilayer dielectric grating.

Grants and funding

The authors would like to thank the Ministry of Science and Technology for financially supporting this research under contract no. MOST 110-2221-E-008-071.