Advances in THz quantum cascade lasers: fulfilling the application potential
Advances in THz quantum cascade lasers: fulfilling the application potential
复制标题
太赫兹量子级联激光器的进展：发挥应用潜力
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
E. Linfield
中科院分区：
文献类型：
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作者：
A. Tredicucci;L. Mahler;T. Losco;Jihua Xu;C. Mauro;Ruedeger Koehler;H. Beere;D. Ritchie;E. Linfield
两年半前就展示了以太赫兹频率运行的量子级联（QC）激光器，从那时起，它们的发展就以非常快的速度进行。大多数研究都集中在增益介质量子设计的新概念以及通过优化制造和波导技术来改进器件结构。各个小组的这些努力已经实现了脉冲模式下约 140 K 的最高工作温度、高达 50 mW 的输出功率以及高达 93 K 的连续波激光。这些进步使得太赫兹 QC 激光器在化学传感、天文学、光谱学和成像等各个领域的应用中越来越有吸引力。为了成功实施，必须满足特定要求，特别是有关发射光谱特性的要求。在这里，我们报告了这个方向的一些最新进展。我们展示了对激光器设计的完美控制，以实现在 2.3 THz 至 4.8 THz 整个范围内精确定义发射频率的设备。此外，还实现了具有分布式反馈谐振器的单模太赫兹激光器，并开发了一种涉及表面等离激元光栅的新技术来提高性能。后者还提供了构建分布式布拉格光栅作为高反射涂层替代品的可能性。最后，研究了允许广泛可调性的解决方案，初步结果说明了外腔设置的可行性。
Quantum cascade (QC) lasers operating at terahertz frequencies were demonstrated two and a half years ago, and, since then, their development has proceeded at a very rapid pace. Most of the research has focused on new concepts for the quantum design of the gain medium as well as on improving device structure by optimizing fabrication and waveguide technology. These efforts by various groups have led to maximum operating temperatures of about 140 K in pulsed mode, output powers of up to 50 mW, and lasing in continuous wave up to 93 K. Such advances are making THz QC lasers more and more appealing for applications in various fields like chemical sensing, astronomy, spectroscopy, and imaging. For their successful implementation, specific requirements have to be addressed, particularly concerning the spectral properties of the emission. Here we report some latest developments in this direction. We demonstrate the perfect control of laser design for the realization of devices with precisely defined emission frequency in the whole range from 2.3 THz to 4.8 THz. Additionally, single-mode THz lasers with distributed feedback resonators have been achieved and a new technique involving surface plasmon gratings has been developed to improve performances. The latter offers also the possibility of constructing distributed Bragg gratings as a replacement for high-reflection coatings. Finally, solutions allowing broad tuneability are examined, with preliminary results illustrating the viability of external cavity set-ups.