TY - GEN
T1 - Single-mode quantum cascade lasers with asymmetric Mach-Zehnder interferometer type Fabry-Perot cavity
AU - Liu, Peter Q.
AU - Wang, Xiaojun
AU - Gmachl, Claire F.
PY - 2013
Y1 - 2013
N2 - Quantum cascade (QC) lasers are compact and versatile light sources suitable for a broad range of absorption spectroscopy based molecular sensing applications. However, for most of such sensing applications, single-mode operation of QC lasers is a prerequisite. Conventional single-mode QC lasers, e.g., distributed feedback (DFB) [1] or external cavity QC lasers [2], have much higher cost than multi-mode simple ridge QC lasers, mainly due to their complicated and demanding device fabrication or time-consuming system integration and alignment processes. In order to achieve more cost-effective single-mode QC lasers, we demonstrate a novel type of laser cavity design which consists of an asymmetric Mach-Zehnder (AMZ) interferometer structure monolithically integrated in a conventional Fabry-Perot (FP) cavity with simple ridge waveguide and as-cleaved facets. Strong wavelength selectivity is introduced by the properly designed AMZ interferometer whose transmission spectrum comprises equidistantly spaced narrow peaks, which in turn selects a specific FP mode associated with the entire laser cavity near the optical gain spectrum peak, effectively facilitating single-mode operation of the laser. Continuously wavelength-tunable single-mode operation of QC lasers is achieved in pulsed mode from 80 K to room temperature and in continuous-wave (CW) mode with high side-mode suppression ratio (SMSR) up to ∼35 dB. The observed spectral characteristics of the tested lasers are described with satisfying accuracy by our model developed for such cavity structures. The fabrication process for such AMZ interferometer type cavities is identical to that for simple ridge lasers, therefore providing a promising solution to achieving more cost-effective single-mode QC lasers.
AB - Quantum cascade (QC) lasers are compact and versatile light sources suitable for a broad range of absorption spectroscopy based molecular sensing applications. However, for most of such sensing applications, single-mode operation of QC lasers is a prerequisite. Conventional single-mode QC lasers, e.g., distributed feedback (DFB) [1] or external cavity QC lasers [2], have much higher cost than multi-mode simple ridge QC lasers, mainly due to their complicated and demanding device fabrication or time-consuming system integration and alignment processes. In order to achieve more cost-effective single-mode QC lasers, we demonstrate a novel type of laser cavity design which consists of an asymmetric Mach-Zehnder (AMZ) interferometer structure monolithically integrated in a conventional Fabry-Perot (FP) cavity with simple ridge waveguide and as-cleaved facets. Strong wavelength selectivity is introduced by the properly designed AMZ interferometer whose transmission spectrum comprises equidistantly spaced narrow peaks, which in turn selects a specific FP mode associated with the entire laser cavity near the optical gain spectrum peak, effectively facilitating single-mode operation of the laser. Continuously wavelength-tunable single-mode operation of QC lasers is achieved in pulsed mode from 80 K to room temperature and in continuous-wave (CW) mode with high side-mode suppression ratio (SMSR) up to ∼35 dB. The observed spectral characteristics of the tested lasers are described with satisfying accuracy by our model developed for such cavity structures. The fabrication process for such AMZ interferometer type cavities is identical to that for simple ridge lasers, therefore providing a promising solution to achieving more cost-effective single-mode QC lasers.
KW - Asymmetric Mach-Zehnder interferometer
KW - Molecular sensing
KW - Monolithic laser cavity
KW - Quantum cascade laser
KW - Single mode
KW - Wavelength tunable
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U2 - 10.1117/12.2012094
DO - 10.1117/12.2012094
M3 - Conference contribution
AN - SCOPUS:84878296716
SN - 9780819494092
T3 - Proceedings of SPIE - The International Society for Optical Engineering
BT - Novel In-Plane Semiconductor Lasers XII
T2 - Novel In-Plane Semiconductor Lasers XII
Y2 - 4 February 2013 through 7 February 2013
ER -