Thermoelectrically Cooled THz Quantum Cascade Laser (IMAGE)
Caption
a) The thermoelectrically cooled laser box with the laser mounted on top of a Peltier element (white square), allowing operation between 195 K and 210.5 K with the laser emitting vertically through the window in the top lid. b) The laser chip as mounted in the laser box, contacted with thin gold wires bonded on top of several laser ridges. c) Schematic of one laser ridge; the horizontal lines show the quantum-well structure formed by layered semiconductors. The ridge (150 micrometres wide) is sandwiched between thin layers of copper. d) Conduction band edge (white lines) tilted by the applied operation bias, with the electron density resolved in energy shown in colour. The electrical bias drives electrons through the non-radiative transitions indicated by the dashed arrow. This pumps the state in the thin well, which becomes more populated than the state in the wider well indicated by the green arrow, allowing for net stimulated emission of terahertz photons.
Credit
Faist group, ETH Zurich
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