Surface plasmon polariton waveguide with metal-insulator-semiconductor (MIS) capacitor structure

Abstract

The invention discloses a surface plasmon polariton (SPP) waveguide with a metal-insulator-semiconductor (MIS) capacitor structure. The SPP waveguide consists of a metal layer (1), an insulating material layer (2), a doped semiconductor layer (3) and a substrate (4), which are arranged from top to bottom, wherein the substrate is grounded through a wire; the metal layer is connected with external voltage through a wire; under proper voltage, a negative real part epsilon r of a complex dielectric function is changed to be positive from an interface of the doped semiconductor layer (3) and the insulating material layer (2) to the interior of the doped semiconductor layer (3), and an area where the epsilon r is negative has characteristics similar to those of metal; an SPP mode can be supported on the interface of the doped semiconductor layer (3) and the insulating material layer (2) and an interface of the positive epsilon r and the negative epsilon r; and the SPP mode supported on the interface of the positive epsilon r and the negative epsilon r is coupled with an SPP mode supported by an interface of the metal layer (1) and the insulating material layer (2) to form a hybrid SPP mode. According to the SPP waveguide, the controllability of a semiconductor can be used for conveniently and efficiently realizing SPP wave regulation and solving a conflict between light field limit and loss.

Description

technical field [0001] The invention relates to a Surface Plasmon Polariton (SPP) waveguide structure and device with a metal-insulator-semiconductor (Mental-Insulator-Semiconductor, MIS) capacitance structure, wherein the semiconductor layer and the insulating material are utilized under the action of an applied voltage The change of the complex dielectric function and its distribution of semiconductor materials near the layer interface can realize the switch of SPP wave transmission and the control of SPP field strength, and has potential applications in photonic integration, nonlinear optics and other fields. Background technique [0002] The SPP wave is an electromagnetic wave guided at the interface between a conductor and a medium, which originates from the collective oscillation of free charges near the surface of the conductor caused by the excitation of an external electromagnetic field. The local enhancement effect brought by the unique generation mechanism of SPP ...

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Problems solved by technology

[0003]①The premise of SPP waveguide to achieve sub-wavelength optical field confinement is to store energy in the oscillation of electrons on the metal surface, so there is an inherent trade-off between optical field confinement and transmission loss Contradiction, especially when the dielectric around the metal has a high dielectric constant (such as: silicon and III-V semiconductor materials), this contradiction is more prominent, and there is no exact solution yet

[0004]②The physical properties of metals are endowed by nature, and it is difficult to carry out human intervention, which determines that even simple switching functions in traditional SPP waveguides are difficult to realize

However, in order to achieve the confinement of the optical field, the SPP waveguide structure needs to limit the spatial distribution of the mode field, which in turn will lead to an increase in the overlap between the mode field and the metal layer, which will increase the waveguide loss, which brings many restrictions to the design of the waveguide.

② Reduce the thickness of the metal layer: Although this method can reduce the overlap between the electromagnetic field and the metal, thereby reducing the waveguide loss to a certain extent, the reduction of the thickness of the metal layer is limited by technology and physics, so this method The method cannot fundamentally solve the problem of metal loss

③Introducing a gain medium into the SPP waveguide structure: This method can compensate the loss of the SPP waveguide to a certain extent, but the gain medium is usually a III-V semiconductor material. Due to the large dielectric constant, when the SPP waveguide is composed of a metal The transmission loss is large, and the field distribution of the SPP wave is mainly concentrated at the interface between the conductor and the medium, and it decays exponentially in the medium, so it is often difficult to achieve sufficient compensation even with the optimal gain medium

However, since the above two schemes adopt a metal-dielectric-metal SPP waveguide structure in the vertical direction (relative to the substrate plane), it is not conducive to integration with other devices.

ShiyangZhu of the Institute of Microelectronics in Singapore proposed a horizontal metal-insulator-Si-insulator-metal structure [Zhu, S., Lo, G.Q., Kwong, D.L., Electro-absorptionmodulationinhorizontalmetal-insulator-silicon-insulator-metalnanoplasmonicslotwaveguides.AppliedPhysicsLetters, 2011.99( 15): p.151114-3], although the above problems are solved, the structure is complicated

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