We have studied the current- and temperature-driven frequency tunability of quantum cascade lasers operating at 2.5 THz. The design of the active medium follows the so-called bound-to-continuum approach. One laser has a Fabry-Perot type resonator. It operates on several modes simultaneously. The other has a distributed feedback structure on top of the active medium which leads to single mode emission. High-resolution spectra of the laser emission by heterodyne mixing with the radiation from a THz gas laser were obtained. In the case of the Fabry-Perot laser, homodyne mixing of its modes was performed too. The emission frequency increases with current for both lasers and all modes. The analysis of the spectra shows up to 2% variation of the difference frequency due to changes of the laser current. The origins of these shifts are discussed.
Spectral characterization of terahertz quantum cascade lasers by heterodyne and homodyne mixing
TREDICUCCI, ALESSANDRO;
2008-01-01
Abstract
We have studied the current- and temperature-driven frequency tunability of quantum cascade lasers operating at 2.5 THz. The design of the active medium follows the so-called bound-to-continuum approach. One laser has a Fabry-Perot type resonator. It operates on several modes simultaneously. The other has a distributed feedback structure on top of the active medium which leads to single mode emission. High-resolution spectra of the laser emission by heterodyne mixing with the radiation from a THz gas laser were obtained. In the case of the Fabry-Perot laser, homodyne mixing of its modes was performed too. The emission frequency increases with current for both lasers and all modes. The analysis of the spectra shows up to 2% variation of the difference frequency due to changes of the laser current. The origins of these shifts are discussed.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
