UNI-TRAVELLING CARRIER PHOTOMIXERS FOR THZ DETECTION

尽管太赫兹(THz)(每秒一万亿次振荡)在成像、传感和安全等应用方面显示出越来越大的潜力，但测量此类信号的技术解决方案的数量有限。此外，诸如Golay单元和光声单元的检测器不能检测THz功率的快速调制。该方案建议研究使用通常用来探测光的半导体器件探测在太赫兹范围内振荡的电磁波的可能性。这种类型的器件对太赫兹探测感兴趣，主要有三个原因；第一，作为半导体器件，它紧凑且相对经济有效；第二，它在室温下工作，而大多数其他太赫兹探测技术必须在非常低的温度下工作；第三，它已经被证明作为太赫兹发射器是有效的。这项工作将集中于调查这样一个事实，即在感兴趣的半导体器件中，作为光检测结果的载流子的速度强烈地依赖于施加到该器件的电场。这种不同意味着，如果设备接收到由天线产生的电场(待检测的太赫兹信号)，它将影响其检测进入光信号的快速变化的方式。这种效应可产生低得多的频率的中频输出，可使用标准电子测量设备进行分析。在方案结束时，预计制造的装置将能够在室温下运行的太赫兹扫描系统中使用。

Although terahertz (THz) (a thousand billion oscillations in a second) show growing potential for applications such as imaging, sensing and security, the number of technological solutions to measure such signals is limited. Further, detectors such as Golay cells and photo-acoustic cells cannot detect fast modulation of the THz power. This programme proposes to investigate the possibility of detecting electromagnetic waves that oscillate in the THz range using a semiconductor device that is normally used to detect light. This type of device is of interest for THz detection for three main reasons; first, as a semiconductor device it is compact and relatively cost effective, second, it operates at room temperature while most other THz detection technologies must be operated at very low temperatures and third, it has already proven to be efficient as aTHz emitter. The work will concentrate on investigating the fact that in the semiconductor device of interest the velocity of the carriers that are the result of light detection is strongly dependent on the electric field that is applied to the device. Such a difference implies that if the device receives an electric field generated by an antenna (the THz signal to be detected) it will affect the way it detect fast changes in an incoming light signal. Such an effect can result in the creation of an intermediate frequency output at a much lower frequency, that can be analysed using standard electronic measurement equipment. At the end of the programme it is expected that a fabricated device will be able to be used in a THz scanning system operating at room temperature.