title: Time-resolved spectral characterization of ring cavity surface emitting and ridge-type distributed feedback quantum cascade lasers by step-scan FT-IR spectroscopy.
abstract: We present the time-resolved comparison of pulsed 2nd order ring cavity surface emitting (RCSE) quantum cascade lasers (QCLs) and pulsed 1st order ridge-type distributed feedback (DFB) QCLs using a step-scan Fourier transform infrared (FT-IR) spectrometer. Laser devices were part of QCL arrays and fabricated from the same laser material. Required grating periods were adjusted to account for the grating order. The step-scan technique provided a spectral resolution of 0.1 cm(-1) and a time resolution of 2 ns. As a result, it was possible to gain information about the tuning behavior and potential mode-hops of the investigated lasers. Different cavity-lengths were compared, including 0.9 mm and 3.2 mm long ridge-type and 0.97 mm (circumference) ring-type cavities. RCSE QCLs were found to have improved emission properties in terms of line-stability, tuning rate and maximum emission time compared to ridge-type lasers.
authors.forename: Markus
authors.initials: M
authors.lastname: Brandstetter
authors.forename: Andreas
authors.initials: A
authors.lastname: Genner
authors.forename: Clemens
authors.initials: C
authors.lastname: Schwarzer
authors.forename: Elvis
authors.initials: E
authors.lastname: Mujagic
authors.forename: Gottfried
authors.initials: G
authors.lastname: Strasser
authors.forename: Bernhard
authors.initials: B
authors.lastname: Lendl
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis / Q000379:methods*; D007834:Lasers; D011789:Quantum Theory; D017550:Spectroscopy, Fourier Transform Infrared / Q000295:instrumentation* / Q000379:methods*