Ultra-Efficient Temporal Shaping Scheme in Nanosecond Pulsed Fiber MOPA System

Nanosecond pulsed lasers with flexible temporal designs have presented encouragingly excellent characteristics in particular applications. Unfortunately, even the currently optimal temporal shaping schemes based on iterative correction of optimization algorithms still suffer from extremely low shaping efficiency in nanosecond pulsed fiber master oscillator power amplifier (MOPA) systems. Users are forced to make trade-offs between iteration cost and shaping precision. Through theoretical analysis and experimental verification, we reveal that pulse misjudgment caused by backward pulse energy transfer and poor performance of optimization algorithms are key factors limiting shaping efficiency, and we propose an ultra-efficient temporal shaping scheme based on innovative pulse fitting method and adaptive ratio algorithm. In a nanosecond pulsed fiber MOPA system with over 40-dB gain, we have achieved high-precision arbitrary temporal designs (close to systematic measurement error (∼0.5%)) with very few iterations (∼10), which is a remarkable progress in terms of shaping efficiency and shaping precision.