Buried heterostructure lasers with highly strained InGaAs-InGaAsP acti
ve regions, emitting at 2 mu m have been fabricated and tested, The la
sers exhibited threshold current densities of 500 A/cm(2) for 1-mm-lon
g cavities, an internal loss of 11 cm(-1), and characteristic temperat
ures as high as 50 degrees C, The gain characteristics were also inves
tigated and a linewidth enhancement factor of 8 was determined.