标题： 室温下，自由空间中基于子带间中红外光电混频器的连续波太赫兹产生 显示英文标题

标题： Room-temperature, continuous-wave Terahertz generation in free-space with an intersubband mid-infrared photomixer

摘要： 我们展示了一种由中红外光子在10$\mu$m波长下泵浦的太赫兹光混频器。 该器件基于双天线结构，其中二维排列的中红外贴片天线谐振器连接到对数螺旋太赫兹天线的电极上。 通过利用AlGaAs-GaAs多量子阱异质结构内的子带吸收，在两个量子级联激光器的差频处相干地产生了光电流。 光电流驱动天线电极，使自由空间中在室温下可调的连续波生成达到1太赫兹。 通过实验研究光混频器的频率响应和暗阻抗，我们证明了高频处观察到的功率滚降是由光激发载流子的本征寿命和器件$RC$时间常数的共同作用所限制的。 在所研究的光谱范围内，我们获得的连续波中红外$\rightarrow$太赫兹转换效率比利用$\chi^{(2)}$过程的单极性器件高几个数量级。 显示英文摘要

摘要： We demonstrate a Terahertz photomixer pumped by mid-infrared photons at 10$\mu$m wavelength. The device is based on a dual-antenna architecture, in which a two-dimensional array of mid-infrared patch-antenna resonators is connected to the electrodes of a log-spiral Terahertz antenna. By exploiting intersubband absorption inside an AlGaAs-GaAs multi-quantum-well heterostructure, a photocurrent is coherently generated at the difference frequency between two quantum cascade lasers. The photocurrent drives the antenna electrodes allowing tunable, continuous-wave generation in free-space up to 1 Terahertz at room temperature. By experimentally studying the photomixer frequency response and dark impedance, we demonstrate that the observed power roll-off at high-frequency is limited by the combined effect of the photoexcited carrier's intrinsic lifetime and of the device $RC$ time constant. In the spectral range investigated we obtain, in continuous-wave, mid-infrared $\rightarrow$ Terahertz conversion efficiencies exceeding by orders of magnitude those of unipolar devices exploiting $\chi^{(2)}$ processes.