Red-edge lasers operating within the 670-780 nm wavelength range have demonstrated considerable importance in remote sensing, with particular value in vegetation monitoring, crop identification and precision agriculture. In this work, a widely tunable red-edge laser based on an optical parametric oscillator driving intra-cavity second harmonic generation is reported. Using a double pass pumping BaGa 4 Se 7 doubly optical parametric resonant oscillator with intra-cavity KTiOPO 4 second harmonic generation, a broadband tunable output was achieved covering the range of 648.12-799.42 nm. The proposed red-edge laser system delivers an output energy above 1 mJ across a tuning range exceeding 150 nm, and the spectral linewidth is measured to be less than 0.3 nm. A comparative analysis, both theoretical and experimental, has revealed that the intra-cavity configuration reduces the threshold and improve the conversion efficiency compared to the extra-cavity configuration. The development of this widely tunable laser, with its tuning range spanning the entire red-edge region, is expected to play a vital role in advancing remote sensing technologies.
Chen et al. (2026) studied this question.