Cleaved-coupled nanowire lasers

Abstract

The miniaturization of optoelectronic devices is essential for the continued success of photonic technologies. Nanowires have been identified as potential building blocks that mimic conventional photonic components such as interconnects, waveguides, and optical cavities at the nanoscale. Semiconductor nanowires with high optical gain offer promising solutions for lasers with small footprints and low power consumption. Although much effort has been directed toward controlling their size, shape, and composition, most nanowire lasers currently suffer from emitting at multiple frequencies simultaneously, arising from the longitudinal modes native to simple Fabry-Pérot cavities. Cleaved-coupled cavities, two Fabry-Pérot cavities that are axially coupled through an air gap, are a promising architecture to produce single-frequency emission. The miniaturization of this concept, however, imposes a restriction on the dimensions of the intercavity gaps because severe optical losses are incurred when the cross-sectional dimensions of cavities become comparable to the lasing wavelength. Here we theoretically investigate and experimentally demonstrate spectral manipulation of lasing modes by creating cleaved-coupled cavities in gallium nitride (GaN) nanowires. Lasing operation at a single UV wavelength at room temperature was achieved using nanoscale gaps to create the smallest cleaved-coupled cavities to date. Besides the reduced number of lasing modes, the cleavedcoupled nanowires also operate with a lower threshold gain than that of the individual component nanowires. Good agreement was found between the measured lasing spectra and the predicted spectral modes obtained by simulating optical coupling properties. This agreement between theory and experiment presents design principles to rationally control the lasing modes in cleaved-coupled nanowire lasers.

Lasing from individual GaAs-AlGaAs core-shell nanowires up to room temperature

“…Our results showed that the AlGaAs shell inhibits nonradiative surface recombination such that clear near-infrared lasing operation can be achieved up to room temperature in this important materials system. The highly nonlinear input-output emission characteristics have strong potential for novel applications in which lasing is used to optically sense the local environment of the NW 34 or in the use of coupled cavity concepts for switching 35 . Although one can expect further improvements of the NW-laser performance by improving the end-facet reflectivity via chemical polishing or by placing them onto patterned substrates for which distributed feedback concepts can be exploited 36 , the direct integration of III/V NW lasers onto silicon substrates for integrated photonics and optical interconnects 37 remains a significant challenge.…”

Nanowire Lasers

“…Mode selection was performed and only one mode was stimulated at the end using two GaN nanowires coupled side by side [110]. Yang et al from Berkeley University followed the same principles, except for performing the coupling axially rather than radially [29]. This technique extended the existing concept of a cleaved-coupled cavity (C3) from conventional ridge laser diodes to nanowire lasers.…”

Polarization features of optically pumped CdS nanowire lasers

“…The consequent next step beyond the proof of nanowire lasing is the modification of the emission, for example by adjusting the resonator properties with a focused ion beam machine (FIB) to create coupled cavity NW lasers [18] or loop resonators [19]. Cadmium sulfide (CdS) nanowire lasers bridge the green spectral region around 2.4 eV, provide excellent optical mode confinement [20] and form quasi 1D optical systems with diameters between 150 nm -500 nm.…”