2.1.2 Lateral metal grating DFB

Ridge waveguide GaSb DFB lasers have also been fabricated by the University of Wurzburg and commercialised by the German company NanoPlus which employ a lateral metal grating at the side of the ridge [20] as depicted in Figure 3. The metal gratings provide strong feedback but generate additional absorption loss in the laser cavity hence the ex-facet laser power is limited to 10 mW levels.

A single mode emission at 2 μm with a side mode suppression ratio of 31 dB is demonstrated in [20] and output power in the 8 mW region. The wavelength tuning rate with temperature is 0.2 nm/<sup>o</sup> C. Reported linewidth measurements are in the 0.3–0.5 MHz region [21].
