Beam size estimation method for mid-infrared lasers using silicon-based photonic semiconductor image sensor

Abstract A beam size estimation method for mid-infrared lasers is proposed. The light-receiving surface of a silicon-based photonic semiconductor image sensor is irradiated with a mid-infrared laser beam to be measured. The semiconductor substrate is heated and excites thermal carriers at the laser incident spot. The distribution of excited carriers is captured and visualized as a monochromatic image by the image sensor. Demonstration using a carbon dioxide laser showed a correlation between the diameter of distributed thermal carriers and that of the incident laser beam with Gaussian distribution. The results indicated that the proposed method is effective for the estimation of beam diameter of mid-infrared lasers.