Precision etching for multi-level AlGaAs waveguides

Liao, Zhongfa; Aitchison, J. S.

doi:10.1364/ome.7.000895

Cited by 14 publications

(8 citation statements)

References 15 publications

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“…The periodicity was set around 240nm to have the photonic mode coupling close to the exciton resonance. We realized the grooves by writing an electron beam sensitive resist, and subsequent pattern transfer into the heterostructure via ICP-Chlorine etching [37][38][39][40]. The etched grating penetrated into the waveguide core, and three different depths were chosen, resulting in different degrees of photonic coupling.…”

Section: Resultsmentioning

confidence: 99%

Fabrication of Nanostructured GaAs/AlGaAs Waveguide for Low-Density Polariton Condensation from a Bound State in the Continuum

Riminucci,

Ardizzone,

Francaviglia

et al. 2022

Preprint

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Exciton-polaritons are hybrid light-matter states that arise from strong coupling between an exciton resonance and a photonic cavity mode. As bosonic excitations, they can undergo a phase transition to a condensed state that can emit coherent light without a population inversion. This aspect makes them good candidates for thresholdless lasers, yet short exciton-polariton lifetime has made it difficult to achieve condensation at very low power densities. In this sense, long-lived symmetry-protected states are excellent candidates to overcome the limitations that arise from the finite mirror reflectivity of monolithic microcavities. In this work we use a photonic symmetry protected bound state in the continuum coupled to an excitonic resonance to achieve state-of-theart polariton condensation threshold in GaAs/AlGaAs waveguide. Most important, we show the influence of fabrication control and how surface passivation via atomic layer deposition provides a way to reduce exciton quenching at the grating sidewalls.

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Section: Resultsmentioning

confidence: 99%

Fabrication of Nanostructured GaAs/AlGaAs Waveguide for Low-Density Polariton Condensation from a Bound State in the Continuum

Riminucci,

Ardizzone,

Francaviglia

et al. 2022

Preprint

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“…This sample sustains polariton modes arising from the strong coupling between the excitonic transition in the QWs and the traveling photonic modes confined by total internal reflection. [31,32] We further process the waveguide by dry etching [33] to obtain a series of diffraction gratings designed to modify both the polariton dispersions and their lifetime around the Γ point in the reciprocal space. In contrast to other passive photonic crystal systems, our polaritonic waveguide is an active system showing a strong photoluminescence (PL) emission under non resonant excitation.…”

Section: Theoretical and Experimental Resultsmentioning

confidence: 99%

Polariton Bose-Einstein condensate from a Bound State in the Continuum

Ardizzone,

Riminucci,

Zanotti

et al. 2021

Preprint

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Exciton-polaritons are weakly interacting bosonic excitations in semiconductor heterostructures that have already shown to display condensation and superfluidity, even at room temperature. Here we show that Bose Einstein condensation of polaritons can occur in a planar waveguide by exploiting coupling to a quasi-bound state in the continuum (BIC). The combination of the ultra-long BIC lifetime and the high finesse and tight confinement of the waveguide geometry allow to achieve a record low threshold energy density. Moreover condensation is reached in a saddle point of the reciprocal space, with peculiar topological dispersion features that give rise to a collimated, spatially confined 1D emission band. The spatial confinement of the BIC state in particular is entirely due to the polariton nonlinearities and appears to be a truly original effect of the polariton BIC. Owing to the largely simplified fabrication as compared to bulky microcavity structures, these results may open a new route to energy-efficient polariton condensation at room temperature in cost-effective heterostructures, ultimately suited for the development of polaritonic integrated optical circuits. Moreover, bringing together bosonic condensation and symmetry-protected photonic eigenmodes could uncover new ways for imparting topological properties onto macroscopic quantum states.

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“…Fabrication of these structures is certainly nontrivial but still practical, as discussed above. After all, techniques including orientation-patterning and QWI have been developed in domain-reversal and domain-suppressed QPM respectively, and high aspect ratio waveguides with low losses and precision etch control have also been achieved [34], [35]. In addition, the use of a higher order mode may first seem intimidating as it often has no easy access.…”

Section: Discussionmentioning

confidence: 99%

Wavelength Conversion Efficiency Enhancement in Modal Phase Matched $\chi^{\hbox{{(2)}}}$ Nonlinear Waveguides

et al. 2021

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Modal phase matching (MPM) is a widely used phase matching technique in AlxGa 1−x As and other χ (2) nonlinear waveguides for efficient wavelength conversions. The use of a non-fundamental spatial mode compensates the material dispersion but also reduces the spatial overlap of the three interacting waves and therefore limits the conversion efficiency. In this work, we develop a technique to increase the nonlinear overlap by modifying the material nonlinearity, instead of the traditional method of optimizing the modal field profiles. This could eliminate the limiting factor of low spatial overlap inherent to MPM and significantly enhance the conversion efficiency. Among the design examples provided, this technique could increase the conversion efficiency by a factor of up to ∼290 in an AlxGa 1−x As waveguide. We further show that this technique is applicable to all χ (2) material systems that utilize MPM for wavelength conversion.

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Precision etching for multi-level AlGaAs waveguides

Cited by 14 publications

References 15 publications

Fabrication of Nanostructured GaAs/AlGaAs Waveguide for Low-Density Polariton Condensation from a Bound State in the Continuum

Fabrication of Nanostructured GaAs/AlGaAs Waveguide for Low-Density Polariton Condensation from a Bound State in the Continuum

Polariton Bose-Einstein condensate from a Bound State in the Continuum

Wavelength Conversion Efficiency Enhancement in Modal Phase Matched $\chi^{\hbox{{(2)}}}$ Nonlinear Waveguides

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