A distributed feedback ridge waveguide semiconductor laser diode having a
waveguide region with a typical thickness of at least 500 nanometers and
an effective refractive index difference between the ridge structure and
exposed portions of the waveguide region which surround the ridge
structure of less than 0.001. This permits the width of the ridge to be
expanded beyond 3.5 microns thus translating directly to higher power
outputs at 1.55 .mu.m wavelengths, where carrier diffusion and carrier
heating limit current density injected into the active region.
