External cavity $InAs∕InP$ quantum dot laser with a tuning range of $166nm$

We have studied the tuning behavior of an external cavity laser in Littrow configuration using antireflection/high-reflection coated $InAs∕InGaAsP∕InP$ quantum dot laser diodes as the amplifying element. Adding the coatings improves the performance of the setup, and the tunability of the external cavity laser output has been increased up to $166nm$⁠. Detailed investigations have revealed that laser diode length and width influence the magnitude of the tuning range. Furthermore, the external differential quantum efficiency is systematically increasing as the external cavity laser wavelength is decreasing. These characteristics are discussed in terms of energy levels available in the inhomogeneous broadening of the self-assembled quantum dots.