Effects of aspheric lens parameters on the coupling efficiency of fiber with Gaussian pulsed laser

Abstract

In the system of photoacoustic microscopy coupled with fiber, the coupling efficiency of fiber is one of most important factors to ensure the photoacoustic intensity under the adequate absorbed energy of pulsed laser for the irradiated tissue. In this work, the effects of aspheric lens parameters on the coupling efficiency of fiber with Gaussian pulsed laser were studied under their reasonable ranges of the parameters. The parameters of the aspheric lens includes the curvature radius, cone constant, thickness, tilt angle, radial deviation of vertical shaft. At the same distances between the aspheric lens, fiber, and the parameters of fiber and pulsed laser, the coupling efficiencies of optical fiber under different values of all parameters of aspheric lens were obtained and compared. The influence laws of all parameters of aspheric lens on the coupling efficiency of optical fiber were all obtained. Studies results show that under the optimal distances of aspheric lens and fiber, with the increase of curvature radius, cone constant, thickness, tilt angle, radial deviation of vertical shaft, the coupling efficiency of optical fiber all first increases then decreases with the Gaussian-liked function. Moreover, the parameters scan optimization method was used to obtain the optimal values of parameters of aspheric lens. Studies show that the coupling efficiency of optical fiber can reach 85.45% when curvature radius is 1.8903mm, cone constant is -2.0627 , thickness is 250μm, tilt angle is 0°, radial deviation is 0mm.