Abstract
Propagation losses in GaAs-based photonic crystal (PhC) waveguides are evaluated near the semiconductor band-edge by measuring the finesse of corresponding Ln cavities. This approach yields simultaneously the propagation losses and the mode reflectivity at the terminations of the cavities. We demonstrate that the propagation losses are dominated by band tail absorption for shorter wavelengths and by fabrication disorder related scattering, near the photonic band edge, for longer wavelengths. Strategies for minimizing losses in such elongated cavities and waveguides are discussed, which is important for the monolithic integration of light sources with such optical elements.
Highlights
Analyzing the sources of propagation loss in semiconductor nano-photonic waveguides is important for constructing compact optical elements, with applications in integrated quantum photonics
We demonstrate that the propagation losses are dominated by band tail absorption for shorter wavelengths and by fabrication disorder related scattering, near the photonic band edge, for longer wavelengths
The quantum dots (QDs)-photonic crystal (PhC) structures were fabricated on a GaAs/Al0.7Ga0.3As membrane wafer grown by molecular beam epitaxy on a (111)B GaAs substrate misoriented by 3° towards [211]
Summary
Analyzing the sources of propagation loss in semiconductor nano-photonic waveguides is important for constructing compact optical elements, with applications in integrated quantum photonics. In such applications, single photons and other non-classical states of light are generated and routed on-chip, and the selection of proper waveguiding schemes is crucial for avoiding excessive photon loss. Strategies for minimizing propagation losses in semiconductor PhC waveguides and associated devices should consider inherent optical material absorption and the impact of fabrication induced disorder and waveguide dispersion effects [3]. In this work we analyze the wavelength dependence of the propagation losses in GaAsbased PhC waveguides by measuring the finesse of PhC Ln cavities of increasing length. We show that the increased losses at shorter wavelengths due to band-tail absorption and at longer wavelengths due to waveguide dispersion result in optimal wavelengths for which propagation losses are minimized
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