We propose a novel waveguide polarization splitter based on the optical analogue of two-photon Rabi oscillations and stimulated Raman adiabatic passage in a three waveguide directional coupler. Both these processes are borrowed from three level quantum mechanical atomic systems, in which an intermediate level is used to transfer the population from one state to another without any population occupation in the intermediate level. To show the practical feasibility of the device, simulations have been carried out on waveguides in lithium niobate and we show that two orthogonal polarizations can be separated at the output using the proposed three waveguide structures. We also show that the proposed structure is robust against changes in phase mismatch parameters, as well as wavelength of operation.

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In this paper, we propose a novel hybrid planar-channel waveguide configuration in which the channel waveguide is submerged within the planar region, with an aim to study two simultaneous three-wave mixing processes under stimulated Raman adiabatic passage. In our study, an input frequency is converted to an output frequency lying very close to or very far from the input frequency via an intermediate frequency. This frequency is in the form of a continuum of modes in the planar region, while all other frequencies propagate as guided modes of the channel waveguide. The continuum of modes at the intermediate frequency allows the simultaneous phase matching to be satisfied over a wide range of wavelengths. As a consequence, this leads to a wideband and efficient conversion from the input to the output frequency without any significant power accumulation at the intermediate stage, which is ensured through the counterintuitive and adiabatic variation in the nonlinear coupling strengths.

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We propose a novel hybrid planar-channel waveguide configuration in lithium niobate (LiNbO3) for quasi phase matched adiabatic parametric amplification exhibiting ultra wide bandwidth and complete conversion of pump into signal and idler pair.