Recent Advances in Quantum Cascade Emitters: Physics, Devices and Applications

Dear Colleagues,

Inherent to the nature of quantum cascade emitters is their complexity and the interdependence of their components. The choice of the growth material depends on the design approach, which depends on the targeted emission characteristics, which in turn depends on the application. Yet, the development process of quantum cascade emitters is not always so straightforward; in fact, it almost never is. Frequency tuning, adaptability, high operating temperatures, high brightness and high output powers are examples of real-life-driven requirements on quantum cascade emitters, that lead often to compromises regarding their individual components, such as the waveguide design, the beam shape, and the possible spectral coverage. Looking for the optimum approach to solve real-life challenges is not always straightforward but still, today, quantum cascade emitters cross existing disciplinary boundaries and open new horizons in multiheterodyne spectroscopy, photonic circuits, holography, frequency combs, microfluidics, photothermal microscopy and real-time sensing, to name a few examples. 

This Special Issue seeks to showcase contributions aimed to tame the complexity of quantum cascade emitter development and research. Starting the third year of the COVID-19 pandemic, we also focus on approaches that illustrate the potential of quantum cascade emitters for medical monitoring and biomedical sensing.  

This Special Issue seeks to showcase research papers, communications, and review articles focus on:

• Volume fabrication of quantum cascade lasers and interband cascade lasers;
• CMOS compatibility and hybrid photonic circuits;
• Terahertz quantum cascade emitters including ring lasers;
• Comb formation, dynamics and applications (including holography);
• QCL-based ATR spectroscopy, microfluidics, photoacoustic spectroscopy, stand-off and photothermal microscopy;
• Applications of quantum cascade emitters in medical monitoring and biomedical sensing;
• Advances in ensemble Monte Carlo modeling;
• Advances in tuning (design approaches, tuning mechanisms, tuning speed, adaptability);
• Frequency stability, noise reduction, injection locking;
• Surface enhanced emission, novel waveguide approaches, dispersion compensation;
• Advances towards highly efficient sources (including high brightness, non-radiative current management, linewidth enhancement factor);
• Non-standard materials for quantum cascade structures (including ZnO);
• Novel design approaches for quantum cascade emitters (including deep-learning).

Dr. Yuri Victorovich Flores
Guest Editor

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• nonlinear dynamics
• broadband photonics
• frequency- and amplitude-modulated combs
• leakage current engineering
• vertically emitting devices
• biomedical sensing
• quantum cascade lasers
• interband cascade lasers
• stand-off spectroscopy
• ATR spectroscopy
• frequency locking and tuning