Research on optical-mechanical-thermal coupling of lenses group of high-power adaptive fiber-optics collimator

The phased fiber laser array is an important technique for achieving high power and high beam quality laser output. The adaptive fiber-optics collimator (AFOC) is a key element of the phased fiber laser array, which is used to transfer the laser from fiber to free space and precisely control the direction of the outgoing collimating beam. To achieve kilowatt-level and higher power laser output from AFOC, it is necessary to design the collimating lens group to meet the high-power demand and analyze the optical-mechanical-thermal coupling effect of this device. According to the dynamic range of AFOC, a large aperture collimating lens group adapted to large deflection angle is presented in this paper. By using the finite element analysis method, the laser is simplified as the body heat source, and the temperature field and stress field at each lens of the AFOC at 1kW-10kW are simulated, and distribution is Gaussian. The wavefront phase analysis of the outgoing beam shows that the aberrations caused by heat absorption of the optical mirror group are mainly spherical aberrations and defocusing terms. At a laser power level of 6kW, the beam quality factor <i>&beta;</i> of the collimated beam can be reduced from 4.6 to 1.6 by compensating thermal defocusing. This study provides a theoretical basis for the design and optimization of high-power AFOC and offers theoretical support for evaluating their reliability.