Amplitude stabilization and active control of a terahertz quantum cascade laser with a graphene loaded split-ring-resonator array

Wei, Binbin and Kindness, Stephen and Almond, Nikita and Wallis, Robert and Wu, Y. and Ren, Yuan and Shi, S. C. and Braeuninger-Weimer, Philipp and Hofmann, Stephan and Beere, Harvey E. and Ritchie, David and Degl'Innocenti, Riccardo (2018) Amplitude stabilization and active control of a terahertz quantum cascade laser with a graphene loaded split-ring-resonator array. Applied Physics Letters, 112 (20): 201102. ISSN 0003-6951

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Abstract

We demonstrate the amplitude stabilization of a 2.85 THz quantum cascade laser with a graphene loaded split-ring-resonator array, acting as an external amplitude modulator. The transmittance of the modulator can be actively changed by modifying the graphene conductivity via electrostatic back-gating. The modulator operates at room temperature and is capable of actively modulating the quantum cascade laser power level and thus stabilizing the power output via a proportional-integral-derivative feedback control loop. The stability was enhanced by more than 10 times through actively tuning the modulation. Furthermore, this approach can be used to externally control the laser power with a high level of stability