DFB Lasers Between 760 nm and 16 μm for Sensing Applications

Recent years have shown the importance of tunable semiconductor lasers in optical sensing. We describe the status quo concerning DFB laser diodes between 760 nm and 3,000 nm as well as new developments aiming for up to 80 nm tuning range in this spectral region. Furthermore we report on QCL between 3 μm and 16 μm and present new developments. An overview of the most interesting applications using such devices is given at the end of this paper

Single mode interband cascade lasers based on lateral metal gratings

The authors are grateful to the European Union for financial support of this work within the FP7 project “WideLase” (No. 318798).Single mode distributed feedback (DFB) interband cascade lasers were realized by placing metal gratings laterally to dry etched ridges. A discrete tuning range of 104 nm could be realized on the same gain material by a variation of the grating period. At room temperature, a 2.4 mm long and 9.8 μm wide ridge with as-cleaved facets emitted more than 6 mW of single mode output power in continuous-wave (cw) mode at a wavelength around 3.8 μm. With typical temperature- and current-tuning rates of 0.31 nm/ °C and 0.065 nm/mA, respectively, a total tuning bandwidth of more than 10 nm could be covered with a single device.Publisher PDFPeer reviewe

ICLs open opportunities for mid-IR sensing

Singlemode interband-cascade lasers (ICLs) enable spectroscopic absorption measurements throughout the entire 3-6 mu m wavelength range while using very little power.</p

Single-mode interband cascade lasers emitting below 2.8 μm

Financial support by the European Commission within the WideLase Seventh Framework Programme Project (Grant Agreement No.: 318798) is gratefully acknowledged.In this work, single-mode distributed feedback (DFB) interband cascade laser (ICL) devices with record short wavelength emission below 2.8 μm are presented. Pulsed measurements based on broad area laser devices with a cavity of 2 mm length and 150 μm width showed threshold current densities of 383 A/cm2 at T = 20 °C and a characteristic temperature T0 of 67 K. Fabricated DFB devices were operated in continuous wave mode at room temperature, with threshold currents of 57 mA and demonstrated side mode suppression ratios of larger than 25 dB. The devices showed current tuning ranges of 7 nm and total (including drive current and temperature) tuning ranges of 12 nm, with respective tuning rates of 21 nm/W, 0.13 nm/mA and 0.29 nm/K. Using the full spectral gain bandwidth of the underlying ICL material, single-mode DFB emission was observed within a wavelength range of 150 nm utilizing different DFB grating periods.Publisher PDFPeer reviewe

Tapered quantum cascade lasers

The authors report on the fabrication of quantum cascade lasers with tapered gain sections. In order to obtain optimal results, index guided devices were realized with tapered angles varying between 0.9 degrees and 2.6 degrees. Compared to a common ridge waveguide laser (divergence of 48.7 degrees), a very small horizontal beam divergence of 6.6 degrees in the single lobe far field is achieved. The tapered quantum cascade lasers show good performance with peak output powers of more than 200 mW at room temperature at an emission wavelength of similar to 8.9 mu m. (C) 2007 American Institute of Physics.</p