Design And Simulation Of Optical Communication Waveguide Devices Based On Optical-quantum Analogy

Recently,the research on quantum-optical analogy has received a lot of attentions.The similarity between quantum mechanics and wave optics allows the scheme developed for manipulating quantum states to be applied to the design of waveguide devices.The ability to transfer particles between set quantum states in a controlled and reliable way is an important topic in quantum physics,and several techniques have been developed to perform population transfers,such as stimulated Raman adiabatic passage,counterdiabatic field,transitionless quantum driving and Lewis-Riesenfeld invariant theory.In this paper,we mainly use Lewis-Riesenfeld invariant theory to study and design the optical communication waveguide devices based on the analogies between quantum mechanics and wave optics.In theory,the device size can be arbitrarily small designed by the method,which provides an attractive scheme for the design of optical devices used in high-speed optical communication and ultra dense integrated system.The main research results are as follows.1.Quantum logic operations are the elemental operations for quantum computing and have been implemented in various time-evolved atomic systems.Here,we present a scheme to simulatively implement the typical quantum NOT-and Hadamard gates operations,alternatively with the coupled three-waveguide structure(rather than the usual atomic levels).two modes in sinuous waveguides encoding the two logic states of a qubit and the mode in the center straight waveguide serve as auxiliary the coupler.Based on the Lewis–Riesenfeld invariant theory,we show that the desired mode conversions for implementing the NOT gate and mode split to realize the Hadamard gate are fast achieved by engineering the coupling parameters between the optical waveguides.The implementations of the logic gates demonstrated here relay on the structure parameters of the waveguides,rather than the durations of time evolutions with the usual driven atomic systems,and thus should be feasible robustly with the current integrated optical technology.2.Experimental demonstrations of coherent dynamics for the driven quantum system are usually limited by their shorter coherent times(due to the inevitable environment noises).Given the Maxwell equation for the electromagnetic waves(EMWs)prorogating in the optical waveguides takes the similar form of the Schr?dinger equation for the driven quantum system,the quantum dynamics in time domain can be simulated by the light propagating along the waveguide in spatial domain.To simulate the fast time evolutions of quantum states during the Landau-Zener(LZ)transitions and Landau-Zenner-Stückelberg(LZS)interferences for the periodically driven two-level systems,we develop an invariant method to design the compacted curved wavguides and demonstrate the LZ transitions and LZS interferometery in the spatial domain.The paper provides a link between optical waveguide design based on quantum-optical analogue and Landau-Zener interferometry,and an alternative scheme is available for the design and fabrication of compact light modulators.3.Due to the limitations either on the level of the sizes or the signal routing channels,the current successful planar integrated optical waveguide circuits is still await for developing3 D integrated technology.Therefore,three-dimensional routing and coupling devices are the key devices for modern information transmission.In this paper we demonstrate an analytical method basing on the invariant engineering to overcome the complication in the usual method by numerically solving the relevant 3D coupled-mode equation for designing the 3D directional waveguide couplers.Our method is based on the quantum-optical analogy,i.e.,the Maxwell equation for the electromagnetic wave prorogating along the waveguide structure in the spatial domain is formally similar to the Schr?dinger equation for the evolving quantum state in the time domain.We find that the spatial-domain invariants can be effectively constructed to solve the 3D coupled-mode equations,analogously solving the dynamical evolutions of quantum systems in the time-domain.As a consequence,as long as appropriately setting the coupling parameters between the 3D interconnected waveguides,the 3D three-waveguide couplers could be designing for various desirably power divisions.As the invariant method is a natural shortcut to the adiabaticity,the compacted devices designed by the invariant-based engineering should be robust against the coupling coefficient variations and the coupler lengths.