InGaAs-Based Well–Island Composite Quantum-Confined Structure with Superwide and Uniform Gain Distribution for Great Enhancement of Semiconductor Laser Performance

In the development of semiconductor lasers, it has been a dream all along to simultaneously obtain extremely wide and uniform gain distribution, because such a gain configuration can greatly enhance semiconductor laser performance. Hence, it has also been a huge challenge to realize this dream so far. In this paper, we are reporting a special InGaAs-based well–island composite quantum-confined structure, with which the best results to date in achieving both superwide and very uniform gain and power distributions are obtained. The spectral flatness of the output power can reach 0.1 dB, and the gain bandwidth is broadened to 6-fold broader than the fwhm (full width at half-maximum) of the standard gain spectrum from a classic InGaAs quantum well under the same carrier density. The formation of the well–island composite quantum-confined structure is associated with the indium-rich island effect in the material growth. The great significance of this work lies in that it is making the above dream come true, since it not only can tremendously increase the spectral tuning range of an InGaAs-based semiconductor laser but also exhibits a great potential on achieving uniform output power over the full spectral tuning range of the laser.