研究目的
Investigating terahertz quantum cascade lasers with a dense array of active micropillars forming the gain medium, identifying different optical regimes based on pillar size relative to emission wavelength, and studying the selection mechanism of the favored laser mode.
研究成果
The study demonstrates the scaling of active pillar arrays for terahertz photonic crystal lasers and subwavelength micropillar array lasers, achieving single mode emission across the spectral gain bandwidth. The operation of subwavelength pillar array devices with lower filling factors is restricted by additional losses, highlighting the need for materials with lower losses or alternative fabrication techniques to overcome these limitations.
研究不足
The operation of subwavelength pillar array devices is limited by additional losses introduced by the planarization material and the roughness of the top waveguide layer. High filling factors are necessary for the realization of nanowire-based terahertz lasers, which are increasingly difficult to realize for very small diameters.
1：Experimental Design and Method Selection:
The study involves the fabrication and characterization of terahertz quantum cascade lasers with active micropillar arrays. Theoretical models and finite element simulations are used to analyze the optical feedback mechanisms and gain enhancement effects.
2：Sample Selection and Data Sources:
The active region is a terahertz quantum cascade structure with a three-well resonant phonon design, grown using molecular beam epitaxy (MBE).
3：List of Experimental Equipment and Materials:
MBE for growth, electron beam lithography for micropillar array definition, reactive ion etching for pillar fabrication, and Fourier transform infrared spectrometer for emission spectrum measurement.
4：Experimental Procedures and Operational Workflow:
Fabrication of micropillar arrays with varying diameters and filling factors, characterization of emission spectra, and analysis of waveguide losses and transparency gain.
5：Data Analysis Methods:
Finite element modeling for eigenmode calculation, analysis of gain enhancement and waveguide losses, and comparison of experimental results with theoretical predictions.
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