创新背景

太赫兹辐射的波长介于微波和可见光之间，可以穿透许多非金属材料并检测某些分子的特征。这些方便的品质可用于广泛的应用，包括机场安全扫描、工业质量控制、天体物理观测、材料的无损表征以及带宽高于当前手机频段的无线通信。

然而，设计用于检测太赫兹波并制作图像的设备存在一些困难，大多数现有的太赫兹设备价格昂贵、缓慢、笨重，并且需要真空系统和极低的温度。

创新过程

研究人员开发了一种新型“相机”，可以在室温和室温压力下快速检测太赫兹脉冲，具有高灵敏度。更重要的是，它可以同时实时捕捉波的方向或“极化”信息，这是现有设备无法做到的。这些信息可用于表征具有不对称分子的材料或确定材料的表面形貌。

这个新系统使用了一种叫做量子点的粒子，它最近被发现可以在太赫兹波的刺激下发射可见光。然后，一种类似于标准电子相机探测器的设备可以记录下可见光，甚至可以用肉眼看到。

该团队生产了两种可以在室温下工作的不同设备：一种利用量子点将太赫兹脉冲转换为可见光的能力，使该设备能够产生材料的图像；另一个产生的图像显示太赫兹波的偏振状态。

这种新型“相机”由几层组成，采用了与微芯片类似的标准制造技术。由窄缝隔开的纳米级平行金线阵列位于基底上；上面是一层发光量子点材料以及用来形成图像的CMOS芯片。被称为偏振计的偏振检波器使用了类似的结构，但采用了纳米级的环形狭缝，这使它能够检测入射光束的偏振。

太赫兹辐射的光子能量极低，这使得它们很难被探测到。因此，这个设备所做的是将微小的光子能量转换成普通相机很容易检测到的可见的东西。在该团队的实验中，该设备能够检测到低强度的太赫兹脉冲，这超过了当今大型昂贵系统的能力。

研究人员展示了探测器的能力，通过拍摄太赫兹照明的一些结构在他们的设备中使用的照片，如纳米间距的金线和用于偏振探测器的环形缝，证明了系统的灵敏度和分辨率。

开发一个实用的太赫兹相机需要一个组件产生太赫兹波来照亮被摄物，另一个组件可以检测到它们。对于后者，目前的太赫兹探测器要么非常慢，因为它们依赖于探测波撞击材料产生的热量，而热量传播很慢，要么它们使用相对较快的光电探测器，但灵敏度非常低。此外，到目前为止，大多数方法都需要一整个太赫兹探测器阵列，每个探测器产生图像的一个像素。

CMOS相机用于捕获太赫兹光束的旋转

虽然研究人员已经用他们的新工作解决了太赫兹脉冲探测的问题，但缺乏好的来源这个问题仍然存在——世界各地的许多研究小组正在努力解决这个问题。在这项新研究中使用的太赫兹源是一个庞大而笨重的激光和光学设备阵列，不容易扩展到实际应用中，但基于微电子技术的新源正在开发中。

这种波长的传统探测器在液氦温度（-452华氏度）下工作，这是从背景噪声中提取出极低能量的太赫兹光子的必要条件。而新设备可以在室温下用传统的可见光相机检测并产生这些波长的图像，这对于那些在太赫兹领域工作的人来说是新奇的。

研究人员表示，有很多方法可以进一步提高新相机的灵敏度，包括进一步缩小组件，以及保护量子点的方法。即使在目前的检测水平上，该设备也可能有一些潜在的应用。

创新关键点

这种新型“相机”由几层组成，采用了与微芯片类似的标准制造技术。由窄缝隔开的纳米级平行金线阵列位于基底上；上面是一层发光量子点材料以及用来形成图像的CMOS芯片。

创新价值

尽管该摄像系统距离商业化还很远，但麻省理工学院的研究人员在需要快速检测太赫兹辐射时，已经开始使用这种新的实验室设备。人们只需要把其中一个插在光束上，用眼睛观察可见光发射，就可以知道太赫兹光束何时开启。这种方法是非常便利的。

The innovative development of a new low-cost camera can detect terahertz pulses with high sensitivity

Researchers have developed a new "camera" that can quickly detect terahertz pulses at room temperature and room pressure, with high sensitivity. What's more, it can simultaneously capture information about the direction or "polarization" of the waves in real time, something existing devices cannot do. These information can be used to characterize materials with asymmetric molecules or to determine the surface morphology of materials.

The new system uses particles called quantum dots, which were recently discovered to emit visible light stimulated by terahertz waves. A device similar to a standard electronic camera detector can then record visible light, which can even be seen with the naked eye.

The team produced two different devices that can work at room temperature: an ability to convert terahertz pulses into visible light using quantum dots, allowing the device to produce images of materials; The other resulting image shows the polarization state of the terahertz wave.

The new "camera" is made up of several layers and uses standard manufacturing techniques similar to those used for microchips. Nanoscale parallel gold wire arrays separated by narrow slits are located on the substrate. On top is a layer of light-emitting quantum dot material and a CMOS chip used to form the image. A polarization detector called a polarimeter uses a similar structure, but with nanometer-scale annular slits, which allow it to detect the polarization of an incoming beam of light.

Terahertz radiation emits photons of extremely low energy, which makes them difficult to detect. So what this device does is convert tiny photon energy into something visible that can be easily detected by a normal camera. In the team's experiments, the device was able to detect low-intensity terahertz pulses, which exceed the capabilities of today's large and expensive systems.

The researchers demonstrated the detector's capabilities, demonstrating the sensitivity and resolution of the system by taking pictures of some of the structures of terahertz lighting used in their device, such as nanospaced gold wires and ring cracks used in polarization detectors.

Developing a practical terahertz camera requires one component to generate terahertz waves to illuminate the subject, and another component to detect them. For the latter, current terahertz detectors are either very slow, as they rely on heat generated by detecting waves hitting the material, which travels slowly, or they use relatively fast photodetectors with very low sensitivity. In addition, most methods so far require an entire array of terahertz detectors, each producing one pixel of the image.

While the researchers have solved the problem of terahertz pulse detection with their new work, the lack of good sources remains a problem - one that many research groups around the world are working on. The terahertz source used in the new study is a large and bulky array of laser and optical devices that are not easily scaled to practical applications, but new sources based on microelectronics are being developed.

Conventional detectors at this wavelength operate at liquid helium temperatures (-452 degrees Fahrenheit), which is necessary to extract very low energy terahertz photons from background noise. And the new device can detect and produce images at these wavelengths at room temperature with traditional visible-light cameras, which will be novel for those working in the terahertz field.

The researchers say there are a number of ways to further improve the sensitivity of the new camera, including further shrinking the components and ways to protect the quantum dots. Even at current levels of detection, the device could have some potential applications.