Importance

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Abstract

An integrated semiconductor device comprising a wavelength-tunable laser, such as a distributed Bragg reflector (DBR) laser, where the laser has a gain section that includes an active layer, and a grating section that includes an active layer and a current-induced grating. A first electrical contact is provided over the gain section to supply current to the gain section and control the output power of the light, and a second electrical contact is provided over the grating section to supply current to the grating section and control the wavelength of the emitted light. The current-induced grating of the present device causes gain in the active layer of the laser to be modulated spatially in the direction of light propagation, thus resulting in only one of the degenerate Bragg modes to oscillate. As the degeneracy of the Bragg modes is broken by current-injection, and not facet reflection, substantially continuous wavelength tuning is possible without the deleterious phenomenon of 'mode hopping.' The present design does not utilize a phase section, and thus eliminates the complex three-way interaction between the gain section, grating section, and a phase section. Alternative grating designs include gain-coupled gratings, complex-coupled gratings, and fractional wave shifted gratings, with relatively strong coupling products (.kappa.L>1.5), which do not rely on facet reflections to break the degeneracy of the Bragg modes.

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First Claim