| With technological progress,the development of traditional waveguides has gradually reached a stage where changes are needed.Due to microelectronics and semiconductor processes,there is a limit line width dominated by quantum effects.Heterogeneous waveguide is a kind of waveguide that uses the special structure of dielectric or metal to control the propagation of electromagnetic waves on subwavelength scale.It breaks through the theoretical diffraction limit with the powerful electromagnetic manipulation ability of subwavelength structure and the strong electromagnetic field confinement and guidance ability of waveguide itself.Heterogeneous waveguide can flexibly and effectively manipulate the amplitude,phase and polarization of electromagnetic waves,realizing mode conversion,efficient modulation,ultra-high sensitivity sensing and other effects.Heterogeneous waveguide can be combined with traditional integrated optical platform to realize highly integrated and multifunctional optical chip.Therefore,the research on heterogeneous waveguide devices has important significance for the development of integrated optics and photonic chip,and has great application potential in the field of optical information processing.Micro-ring resonator and phase modulator are one of the most commonly used on-chip waveguide sensor devices and modulator devices respectively.The current micro-ring sensors have the following shortcomings: first,complex micro-ring resonators often have small manufacturing tolerance and high cost;second,there is a contradiction between miniaturization design and high sensitivity design;third,silicon waveguide optical sensors have high temperature dependence,and thermal drift will reduce the reliability of refractive index sensors.And the current phase modulators have the following shortcomings: first,the modulation length of phase modulator is too long,which is not conducive to photon integration;second,the modulation voltage of traditional phase modulator is too high,and the energy consumption is large;third,the bandwidth of modulator is limited.This paper focuses on the principle and technology of heterogeneous waveguide devices,and the specific research contents are as follows:(1)A temperature-insensitive heterogeneous waveguide micro-ring resonator with double-layer U-shaped waveguide for sensing application is proposed and theoretically studied.Based on the athermal design theory,the optical field is more confined at the interface between silicon core and aqueous solution,realizing that the effective mode refractive index hardly changes with temperature.The unique structure of double-layer Ushaped waveguide not only forms a ring-shaped optical field confinement,but also releases the evanescent field from the waveguide through the coupling of upper and lower layers,enhancing the interaction between light and matter,and improving the sensing ability.The results show that the sensitivity is 496 nm/RIU±5 pm/K.Within a temperature variation range of 3.2 K,it can be considered that the measurement result is independent of environmental temperature change.(2)An ultra-compact heterogeneous waveguide phase modulator based on split-ring magnetic resonance is proposed and theoretically studied.The split ring metasurface array on the upper layer of the waveguide is used to achieve optical field control within the waveguide.With the help of split-ring magnetic resonance,the localization of the light field and the electrical coupling between the split-ring are realized,which enhances the interaction between light and matter,resulting in the effective refractive index being more sensitive to the change of conductivity of graphene.And the change of effective refractive index leading to the change of phase.The phase modulator has an ultra-short modulation length of only3.65 μm,a wide modulation bandwidth of 116.8 GHz and a low energy consumption of263.49 f J/bit,which can realize phase change from 0 to π.By optimizing the structure,the energy consumption can be further reduced to 90.69 f J/bit. |
