Propagating Polaritons in III-Nitride Slab Waveguides

Abstract

We report on III-nitride waveguides with c-plane GaN/AlGaN quantum wells in the strong lightmatter coupling regime supporting propagating polaritons. They feature a normal mode splitting as large as 60 meV at low temperatures thanks to the large overlap between the optical mode and the active region, a polariton decay length up to 100 µm for photon-like polaritons and lifetime of 1-2 ps; with the latter values being essentially limited by residual absorption occurring in the waveguide. The fully lattice-matched nature of the structure allows for very low disorder and high in-plane homogeneity; an important asset for the realization of polaritonic integrated circuits that could support nonlinear polariton wavepackets up to room temperature thanks to the large exciton binding energy of 40 meV.

Edge-emitting polariton laser and amplifier based on a ZnO waveguide

“…The geometry is very appealing because of its simple technological realization, easier electrical injection, and the possibility it opens up to design integrated polaritonic circuits with very limited radiative losses. Guided polaritons have been observed and studied in GaAs 33 , 34 , organic materials 30 , 35 , GaN 36 , and transitional metal dichalcogenides 37 (TMD), with recent reports of nonlinear polariton–polariton interaction 31 , 38 . This horizontal geometry is very favorable for straightforward implementation of polariton integrated circuits with the use of topological protection, such as in the recently reported “topological lasers” 39 , 40 .…”

Strong Coupling in Microcavity Structures: Principle, Design, and Practical Application

“…Several studies considered alternative microcavity polariton designs, for example, guided Bloch surface wave polaritons or TPP structures. A feasible system is a semiconductor planar waveguide with excitonic material embedded in the center . Compared with DBRs, waveguides operate naturally for large plane waves and group velocities; hence the polarizer spreads over a long distance.…”

“…Ciers et al . recently showed strong coupling between propagating TE 0 optical mode in compound semiconductor slab waveguides and c‐plane GaN/(Al, Ga)N QW excitons.…”

“…Strong coupling has also been demonstrated in other cavity structures, including waveguides and whispering gallery . Ciers et al . demonstrated strong coupling in III‐nitride slab waveguides.…”

Polariton relaxation and polariton nonlinearities in nonresonantly cw-pumped III-nitride slab waveguides

“…Beyond pure fundamental aspects, the remarkable physical phenomena ensuing from the mixed light-matter nature of polaritons open promising perspectives for the realization of low power consumption and small footprint active optical devices [12][13][14][15][16][17]. This is especially the case for slab WGs, which exhibit eigenmodes characterized by fast inplane propagation with group velocities on the order of 10 7 m/s, whose geometry makes them more suitable for integration into photonic integrated circuits than their planar microcavity counterparts [4,11,[18][19][20][21][22][23][24][25].…”