Phase-locked array of quantum cascade lasers with an intracavity spatial   filter
  Phase-locking an array of quantum cascade lasers is an effective way to achieve higher output power and beam shaping. In this article, based on Talbot effect, we show a new-type phase-locked array of mid-infrared quantum cascade lasers with an integrated spatial- filtering Talbot cavity. All the arrays show stable in-phase operation from the threshold current to full power current. The beam divergence of the array device is smaller than that of a single-ridge laser. We use the multi-slit Fraunhofer diffraction mode to interpret the far-field radiation profile and give a solution to get better beam quality. The maximum power is just about 5 times that of a single-ridge laser for eleven-laser array device and 3 times for seven-laser array device. Considering the great modal selection ability, simple fabricating process and the potential for achieving better beam quality and smaller cavity loss, this new-type phase-locked array may be a hopeful and elegant solution to get high power or beam shaping. 
Lei Wang, Jinchuan Zhang, Zhiwei Jia, Yue Zhao, Chuanwei Liu, Yinghui   Liu, Shenqiang Zhai, Zhuo Ning, Fengqi Liu
physics.optics cond-mat.mes-hall