Present day silicon chips for communication and computing are densely packed with transistors and other passive elements. Metal-based connections between these are lossy and generate heat. Therefore on-chip optical communication links are desired. The crucial device to make this possible is a monolithic diode laser. This is the first demonstration of such a monolithic laser on (001) silicon emitting at the eye-safe wavelength of 1.3mm. The laser is made with nitride-based semiconductor nanowire arrays.
A monolithic diode laser on (001)Si is useful for silicon photonics. III-nitride based nanowires can be grown catalyst-free on silicon and other substrates. The nanowire diameter and density in an array can be varied over wide ranges. Single or multiple InGaN disks can be inserted in Ga(In, Al)N nanowires and the alloy composition in the disk can be varied to tune the luminescence from visible to near infrared. Such nanowires have desirable properties such as very low density of extended defects and minimal strain. They can also be selectively doped n- and p-type, thereby enabling the formation of junction diodes as with planar materials. These favorable attributes have been exploited to design, epitaxially grow and characterize the first edge-emitting electrically pumped InN/In(Ga)N disk-in-nanowire lasers with the peak of the coherent emission at ~1.3µm. It may be noted that light sources with emission at wavelengths larger than 590nm cannot be realized with InGaN/GaN quantum wells.
The output power and spectral characteristics of the nanowire laser emitting at 1.3mm and suitable for silicon photonics and other applications.