pISSN 0374-4914 eISSN 2289-0041

## Research Paper

New Phys.: Sae Mulli 2021; 71: 301-304

Published online March 31, 2021 https://doi.org/10.3938/NPSM.71.301

## Comparison of Simulation and Optical Characteristic of a High-Efficiency Beam Combination Method for Quantum Cascade Lasers

Ji Yoon GWAG, Young Ho PARK, Soo Hyung CHO*

Hanwha Systems, Seongnam 13524, Korea

Correspondence to:jiyoon89.gwak@hanwha.com

Received: November 27, 2020; Revised: February 1, 2021; Accepted: February 2, 2021

### Abstract

Recently, the quantum cascade laser (QCL) has been spotlighted as a next-generation light source in the mid-infrared region because of its increase in optical power due to the development of manufacturing technology. However, the optical power of a single QCL is limited by the self-heating effect. Therefore, high-efficiency beam combination technology is essential to achieve a high-power mid-IR laser. In this paper, we demonstrate a simple and effective beam combination method that can be used for QCLs in the 3.85 -- 4.15 $\mu$m wavelength region. We achieved a high 89.0% efficiency by combining three QCLs using flat mirrors. In addition, we adjusted the divergence angles of the fast axis and the slow axis equally for easy application in various wavelength regions.

Keywords: Quantum cascade laser, Beam combination, Optics