Wavelength selection for quantum cascade lasers by cavity length

• Published in: Applied physics letters Vol. 94; no. 9; pp. 091109 - 091109-3
• Main Authors: Young, Christina, Cendejas, Richard, Howard, Scott S., Sanchez-Vaynshteyn, Wendy, Hoffman, Anthony J., Franz, Kale J., Yao, Yu, Mizaikoff, Boris, Wang, Xiaojun, Fan, Jenyu, Gmachl, Claire F.
• Format: Journal Article
• Language: English
• Published: American Institute of Physics 02-03-2009
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.3093422

A systematic shift in spectral emission wavenumbers in quantum cascade lasers (QCLs) is observed over a variation in cavity lengths from 0.5 to 3 mm resulting in a gain peak shift ranging from 2404 to
2286

cm
−
1
. Thereby, a wavelength selection range of
118

cm
−
1
is provided, which is sufficiently broad for selecting the laser emission across the entire
CO
2
absorption band at
2326

cm
−
1
(
4.3

μ
m
)
. In contrast to current QCL wavelength selection techniques, modifying the cavity length is a straightforward postprocessing procedure. Experimental evidence confirms that this frequency shift is due to a change in threshold voltage and applied electric field as a function of cavity length which is in agreement with the theory.