Terahertz quantum-cascade-laser source based on intracavity difference-frequency generation


Mikhail A. Belkin, Federico Capasso, Alexey Belyanin, Deborah L. Sivco, Alfred Y. Cho, Douglas C. Oakley, Christopher J. Vineis, and George W. Turner. 2007. “Terahertz quantum-cascade-laser source based on intracavity difference-frequency generation.” NATURE PHOTONICS, 1, 5, Pp. 288-292. Publisher's Version
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The terahertz spectral range (lambda = 30-300 mu m) has long been devoid of compact, electrically pumped, room-temperature semiconductor sources(1-4). Despite recent progress with terahertz quantum cascade lasers(2-4), existing devices still require cryogenic cooling. An alternative way to produce terahertz radiation is frequency down-conversion in a nonlinear optical crystal using infrared or visible pump lasers(5-7). This approach offers broad spectral tunability and does work at room temperature; however, it requires powerful laser pumps and a more complicated optical set-up, resulting in bulky and unwieldy sources. Here we demonstrate a monolithically integrated device designed to combine the advantages of electrically pumped semiconductor lasers and nonlinear optical sources. Our device is a dual-wavelength quantum cascade laser(8) with the active region engineered to possess giant second-order nonlinear susceptibility associated with intersubband transitions in coupled quantum wells. The laser operates at lambda(1) = 7.6 mu m and lambda(2) = 8.7 mu m, and produces terahertz output at lambda = 60 mu m through intracavity difference-frequency generation.
Last updated on 05/29/2020