It is proposed to apply hydrostatic pressure to vary the built-in strain to conduct a study of the physical processes responsible for the improvements in the laser characteristics with strain. Calculations of the strain in the laser structures under pressure show that an additional strain is generated in the laser active area due to the difference in the elastic constants between the active and cladding years. The cladding and carrier confinement layers, being much thicker than the active layer, deform isotropically with pressure. The additional strain created by high pressure will allow for the first time the tuning of the initial built-in strain from compressive to tensile in a single device. In t his way, it will be possible to evaluate solely the effect of strain and avoid variations in the growth conditions which take place when the effect of strain is evaluated by comparing devices from different waters with different compositions.
