Quantum cascade lasers are semiconductor lasers based on intersubband transitions that have developed rapidly and become the most suitable mid-infrared laser sources, due to their compactness, efficiency and high room temperature performances. High-power mid-infrared quantum cascade lasers are performant sources for optical countermeasures, including night vision blinding and missile out steering. However, some drawbacks arise with high power lasers that usually lead to a strong degradation of the beam quality. For instance, beam steering is known to be one of the limiting factors inducing an irregular distribution of the optical power within the near-field beam profile. This phenomenon has already been observed in high power quantum cascade lasers before and can be explained by four-wave mixing interaction among the existing transverse modes. It dramatically degrades the far-field of the laser emission, and prevents its use for applications where high beam quality is required. In this work, we show for the first time that the use of a small amount of optical feedback reinjected into a high power quantum cascade laser emitting at 4.6 μm and with poor beam quality allows a total suppression of the beam steering effect without sacrificing the near-field profile.
Louise Jumpertz, Simon Ferré, Mathieu Carras, and Frédéric Grillot, "Beam steering in quantum cascade lasers with optical feedback," Proc. SPIE 10111, Quantum Sensing and Nano Electronics and Photonics XIV, 101112F (Presented at SPIE OPTO: February 02, 2017; Published: 27 January 2017); https://doi.org/10.1117/12.2251778.
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