CAREER: Mid-infrared Intersubband Polaritonics

该计划的目标是开发基于光与极薄半导体层之间强量子相互作用的全新中红外光源，用于医学，工业和国土安全。 在电磁光谱的中红外部分（3-30微米）中操作的光学设备能够实现灵敏的成像和检测，因为许多分子在这些波长处表现出特异性和强吸收光谱。 为这些应用开发中红外光源的主要挑战之一是产生光的物理过程非常低效。 我们提高中红外光源效率的方法是设计光和物质之间的强量子力学相互作用，创造同时是光和物质激发的量子态，并在设备被电泵浦时研究这些混合态。 在这样做的过程中，我们的愿望是通过展示工程技术，制造，表征和控制包含强光-物质相互作用的设备，为这些光电设备开发一套工具。 除了推进中红外技术，该计划还通过开发和举办工程日来解决科学，技术，工程和数学的教育和多样性问题，这些工程日围绕着当地学校的学生实践光学挑战而建立。该计划旨在提高中红外光电器件的辐射量子效率。 然而，远离增量改进现有的设备，如量子级联激光器，我们的方法寻求发展的基础上，从电注入极化激元状态，产生强的光-物质之间的相互作用，在谐振器中的光子场和电子子带间跃迁量子威尔斯集成到谐振器的量子态之间。 这些新型光电器件将为中红外传感和成像应用所需的宽带宽、高功率非相干光源提供新的途径。 我们的方法是一个综合的理论，计算和实验的努力，（1）调查中红外微腔，（2）提高光子与中红外子带间跃迁的耦合，（3）实现有效的子带间极化激元态的电注入。 我们将研究一系列的腔和导带设计在GaAs和InP基材料系统。 我们所有的材料都将通过分子束外延生长，并在最先进的纳米制造设施中制造成器件。 我们将使用傅里叶变换光谱作为温度，谐振器和导带设计，和电泵浦功率的函数来表征器件。 我们的工作将为中红外子带间极化激元集成到光电子器件中奠定基础。 此外，子带间极化激元态的有效电注入也将有利于超可调谐量子级联激光器的发展，而光-物质耦合极限的研究将是中红外探测器和量子光学界感兴趣的。 该计划的最终结果是雄心勃勃的：电注入子带间极化激元发射器的发展，与现有的中红外子带间发射器相比，发射功率和效率提高了四个数量级以上。

The goal of this program is to develop fundamentally new mid-infrared optical sources based on strong quantum interactions between light and extremely thin layers of semiconductors for applications in medicine, industry, and homeland security. Optical devices operating in the mid-infrared portion of the electromagnetic spectrum (3-30 microns) enable sensitive imaging and detection because many molecules exhibit specific and strong absorption spectra at these wavelengths. One of the primary challenges of developing mid-infrared sources for these applications is that the physical process that generates light is very inefficient. Our approach to improving the efficiency of mid-infrared optical sources is to engineer strong quantum mechanical interactions between light and matter, creating quantum states that are simultaneously light and matter excitations, and to study these hybrid states when the device is electrically pumped. In doing so, our desire is to develop a set of tools for these optoelectronic devices by demonstrating techniques for engineering, fabricating, characterizing, and controlling devices that incorporate strong light-matter interactions. Beyond advancing mid-infrared technologies, this program also addresses education and diversity in science, technology, engineering, and mathematics by developing and hosting Engineering Days that are built around hands-on optics-based challenges for students at local schools.This program aims to improve the radiative quantum efficiency of mid-infrared optoelectronic devices. However, far from incremental improvements to existing devices such a quantum cascade lasers, our approach seeks the development of fundamentally new devices based on electrically injected polariton states that arise from strong light-matter interactions between the photon field in a resonator and electronic intersubband transitions between the quantized states of quantum wells integrated into the resonator. These novel optoelectronic devices will provide a new approach for wide-bandwidth, high-power incoherent sources needed for applications in mid-infrared sensing and imaging. Our approach is an integrated theoretical, computational, and experimental effort to (1) investigate mid-infrared microcavities, (2) improve coupling of photons with mid-infrared intersubband transitions, and (3) implement efficient electrical injection of intersubband polariton states. We will investigate a range of cavity and conduction band designs in both GaAs- and InP-based material systems. All of our materials will be grown by molecular beam epitaxy and fabricated into devices in a state-of-the-art nanofabrication facility. We will characterize the devices using Fourier transform spectroscopy as a function of temperature, resonator and conduction band design, and electrical pumping power. Our efforts will lay the groundwork for integrating mid-infrared intersubband polaritons into optoelectronic devices. Furthermore, efficient electrical injection of intersubband polariton states will also benefit the development of ultra-tunable quantum cascade lasers, while the investigation of the limits of light-matter coupling will be of interest to the mid-infrared detector and quantum optics communities. The end result of this program is ambitious: the development of electrically injected intersubband polariton emitters with more than four orders of magnitude improvement in the emitted power and efficiency compared to existing mid-infrared intersubband emitters.