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Laser dazzling on complementary metal oxide semiconductor (CMOS) image sensors is an effective method in optoelectronic countermeasures. However, previous research mainly focused on the laser dazzling under far fields, with limited studies on situations that the far-field conditions were not satisfied. In this paper, we established a Fresnel diffraction model of laser dazzling on a CMOS by combining experiments and simulations. We calculated that the laser power density and the area of saturated pixels on the detector exhibit a linear relationship with a slope of 0.64 in a log-log plot. In the experiment, we found that the back side illumination (BSI-CMOS) matched the simulations, with an error margin of 3%, while the front side illumination (FSI-CMOS) slightly mismatched the simulations, with an error margin of 14%. We also found that the full-screen saturation threshold for the BSI-CMOS was 25% higher than the FSI-CMOS. Our work demonstrates the applicability of the Fresnel diffraction model for BSI-CMOS, which provides a valuable reference for studying laser dazzling. [ABSTRACT FROM AUTHOR]

A photonic lantern is a coherent beam combination device that can increase the fiber laser brightness by adaptively controlling the input light properties, such as phase, intensity, and polarization. However, the control effect is closely related to the initial optical field, which affects the convergence speed to obtain the optimum solutions. In this work, we propose a novel control strategy using the prior structural information of the photonic lantern. Taking a 6 × 1 photonic lantern as an example, we calculate the transmission matrix of the photonic lantern. The initial optical field conditions, fed as the control inputs, for various mode outputs can be obtained. Compared with the random and equal amplitude control methods, the preset method from the transmission matrix presents a significant improvement of the desired mode content. Our optimization method is generally useful for adaptive control systems to improve their performance, taking advantage of their own structural information. [ABSTRACT FROM AUTHOR]

We carry out a detailed investigation of TMI mitigation by pump modulation based on multiple current waveforms in a fiber laser oscillator. Compared with continuous wave (CW), the modulation of various waveforms, including sinusoidal wave, triangular wave, and pulse wave with a duty cycle of 50% and 60%, can increase the TMI threshold. The average output power of a stabilized beam is boosted via the adjustment of phase difference between the signal channels. The TMI threshold is increased to 270 W under a modulation of pulse wave (duty cycle: 60%) with a phase difference of 440 μs, where the beam quality is 1.45. This threshold can be further improved by adding groups of pump LDs and drivers, which is a promising approach for beam stabilization of high-power fiber lasers. [ABSTRACT FROM AUTHOR]