Wolfgang Zeller

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.

High power DFB laser diodes

We present a new design that reduces the far field angles and increases the threshold for catastrophic optical damage of distributed feedback lasers with lateral gratings. The layer structure consists of an asymmetric large optical cavity where the active region is located very close to the upper cladding layer. The position and large refractive index of the active region results in a mode profile that is suitable for good coupling to the lateral grating. A large mode diameter on the facets is achieved by tapering the ridge from its original width to sub-micron dimensions close to the facets. This taper pushes the optical mode down into the core of the large optical cavity, leading to an increase of the mode diameter. The concept is fully compatible with standard facet coating and passivation processes. We present 980 nm laser diodes based on this concept with 5.2° and 13° full-width half-maximum of the farfield and catastrophic optical damage thresholds of 1.6 W.

DFB Lasers from 760 nm to 3400 nm for Sensing Applications

We describe the status quo concerning DFB laser diodes between 760 nm and 3400 nm as well as new developments aiming for up to 80 nm tuning range, high power and low linewidth in this spectral region.