Semiconductor lasers with internal wavelength selection

Laser diodes with a deep built-in trapezoidal large-period diffraction grating have been developed on the basis of InGaAs/GaAs/AlGaAs heterostructures. The electroluminescence and stimulated emission spectra and light-current characteristics of diffraction-grating laser diodes have been studied. A substantial narrowing of both the luminescence and stimulated emission spectra was achieved due to the spectral selectivity of the grating. The maximum output optical power was 1 W at a drive current of 4 A. At the highest power, the lasing spectrum had a FWHM of ～2 Å. A narrowing of the lasing spectrum of the diffraction-grating laser by tens of times was demonstrated, compared with that of a laser with a Fabry-Perot cavity.