  Large-scale optoelectronics integration is strongly limited by the lack of
efficient light sources, which could be integrated with the silicon
complementary metal-oxide-semiconductor (CMOS) technology. Persistent efforts
continue to achieve efficient light emission from silicon in the extending the
silicon technology into fully integrated optoelectronic circuits. Here, we
report the realization of room-temperature stimulated emission in the
technologically crucial 1.5 micron wavelength range from Er-doped GaN
multiple-quantum wells on silicon and sapphire. Employing the well-acknowledged
variable stripe technique, we have demonstrated an optical gain up to 170 cm-1
in the multiple-quantum well structures. The observation of the stimulated
emission is accompanied by the characteristic threshold behavior of emission
intensity as a function of pump fluence, spectral linewidth narrowing and
excitation length. The demonstration of room-temperature lasing at the minimum
loss window of optical fibers and in the eye-safe wavelength region of 1.5
micron are highly sought-after for use in many applications including defense,
industrial processing, communication, medicine, spectroscopy and imaging. As
the synthesis of Er-doped GaN epitaxial layers on silicon and sapphire has been
successfully demonstrated, the results laid the foundation for achieving hybrid
GaN-Si lasers providing a new pathway towards full photonic integration for
silicon optoelectronics.
