Spatial adiabatic passage of light in waveguide structures

Germano Montemezzani

Hassan Oukraou, Laura Vittadello, Virginie Coda +5 more

We study adiabatic light transfer in systems of two coupled waveguides with spatially varying detuning of the propagation constants, providing an analogy to the quantum phenomena of rapid adiabatic passage (RAP) and two-state stimulated Raman adiabatic passage (two-state STIRAP). Experimental demonstration using a photoinduction technique confirms the robust and broadband character of the structures that act as broadband directional couplers and broadband beam splitters, respectively.

Ricard Menchon-Enrich, Andreu Llobera, Jordi Vila‐Planas +3 more

We report the first experimental realization of an analogous of the Stimulated Raman Adiabatic Passage (STIRAP) technique [1] working as a light spectral filter [2,3]. The system consists of three identical coupled total internal reflection silicon oxide waveguides designed such that there is a counterintuitive variation of the evanescent couplings between the waveguides along the propagation direction (see Fig.1(a)). If couplings are strong and wide enough along the propagation direction, which only occurs for long enough wavelengths, this geometry allows for an adiabatic following of a supermode that implies only the outermost waveguides. Thus, if light is injected into the right waveguide of our device, after propagating along the system, long wavelengths are transferred into the left output whereas short wavelengths end up into the central and right outputs. In this way, the system operates as a simultaneous high and low-pass spectral filter in the visible range. We refer to this device as Spatial Adiabatic Passage (SAP) filter. Regarding the filtering efficiency, the measured stopband reaches values up to -11dB for the left output, and around -20dB for the right plus central outputs. The passband values are close to 0dB for both cases. Fig. 1(b) shows the experimentally measured intensities at the output of the left waveguide and the sum of the outputs of the right and central waveguides as the transmittance relative to the total output intensity for one of the fabricated devices.

Zhaoming Zhu

Nida Naim, Li Deng, Yueping Niu +1 more

Abstract We discuss in this paper the optical analog to rapid adiabatic passage (RAP) and two-state stimulated Raman adiabatic passage (STIRAP) in coupled waveguides with nonlinearity. With the increase of the power of light propagating in waveguides, the nonlinearity can significantly prevent the two adiabatic passages from being successfully simulated. Nevertheless, we find that the negative role of the nonlinearity can be avoided under the assistance of the method of resonance-locked inverse engineering. The method implies redesigning the longitudinally varying detuning of the propagation constants. We further point out that the variation of the detuning does not have to be exactly the same as what the method suggests. As long as the detuning has similar trend to what the method shows, the RAP and two-state STIRAP can still be realized in nonlinear waveguides. This makes the waveguide structure more simpler. Based on our study, the applications of two-state adiabatic passages in designing directional couplers and beam splitters are extended from linear to nonlinear waveguides.

Virginie Coda, Hassan Oukraou, Andon A. Rangelov +1 more