My Research and Inventions

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Introduction

Si nanowire fabrication technology

fiber/waveguide coupling setup

devices made of Si-waveguides

directional coupler

integration: plasmonic + Si waveguides

two technology of integration

Out-plane plasmonic confinement

plasmonic isolator

III-V plasmonic

AlGaAs waveguide (800 nm)

AlGaAs waveguide (1550 nm)

Si wire waveguide (1550 nm)

plasmonic on GaAs (800 nm)

plasmonic on GaAs (1550 nm)

plasmonic on Si (1550 nm)

plasmons in metal strip

in-plane confinement of plasmons

samples very old

 

 

 

Introduction

Si nanowire fabrication technology

fiber/waveguide coupling setup

devices made of Si-waveguides

directional coupler

integration: plasmonic + Si waveguides

two technology of integration

Out-plane plasmonic confinement

plasmonic isolator

III-V plasmonic

AlGaAs waveguide (800 nm)

AlGaAs waveguide (1550 nm)

Si wire waveguide (1550 nm)

plasmonic on GaAs (800 nm)

plasmonic on GaAs (1550 nm)

plasmonic on Si (1550 nm)

plasmons in metal strip

in-plane confinement of plasmons

samples very old

 

 

 

Introduction

Si nanowire fabrication technology

fiber/waveguide coupling setup

devices made of Si-waveguides

directional coupler

integration: plasmonic + Si waveguides

two technology of integration

Out-plane plasmonic confinement

plasmonic isolator

III-V plasmonic

AlGaAs waveguide (800 nm)

AlGaAs waveguide (1550 nm)

Si wire waveguide (1550 nm)

plasmonic on GaAs (800 nm)

plasmonic on GaAs (1550 nm)

plasmonic on Si (1550 nm)

plasmons in metal strip

in-plane confinement of plasmons

samples very old

 

 
Integration of AlGaAs dielectric waveguides and plasmonic waveguides

Technology

These results were reported in this paper V. Zayets, H. Saito, K. Ando, S. Yuasa , "Long-distance propagation of a surface plasmon on the surface of a ferromagnetic metal," Optics Express 23, 12834-12839 (2015).

Fig.1 Integration of AlGaAs dielectric waveguide and Fe/MgO/AlGaAs plasmonic waveguide

click on image to enlarge it

Fe is not transparent and the light propagation from input waveguide to output waveguide is blocked by the Fe. However, a surface plasmon is excited at Fe-MgO/AlGaAs interface and light can reach from input to output.

Since the Fe is magneto-optical material, the structure can be optimized that light can pass only in forward direction, but light is blocked in opposite direction. Such devices is called optical isolator or plasmonic isolator

Important technologies for the integrated plasmonic:

(technology 1) Looser out-of-plane confinement by a double-layer dielectric.

Details of the technology (1) are described here

It was used

(technology 2) Lateral optical confinement out-of-metal edge. Use of wedge, bridge and similar designs of a plasmonic structures.

Details of the technology (2) are described here

It was not used

Instead another method for a in-plane confinement out of metal edge was used.

 

 

 

 

 

Fig.2 Plasmonic waveguide Fe/MgO/AlGaAs integrated with AlGaAs dielectric waveguides.

click on image to enlarge it

The cross-sectional SEM images of dielectric and plasmonic waveguides are shown. The metal is brighter. The oxide is darker.

The field distributions of a waveguide mode and a plasmon are shown in yellow color.

 

 

 

 

 

 

 

 

 

 

 

 

 

Fig.3 Plasmonic waveguide Fe/MgO/AlGaAs integrated with AlGaAs dielectric waveguides.

click on image to enlarge it

Top view

optical microscope

Top view

SEM

Cross-sectional view

SEM

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Fiber-to-fiber transmission of the AlGaAs/MgO/Fe plasmonic structure embedded into the AlGAs/GaAs optical waveguide.

plasmon propagation loss: 0.17 dB/um
Coupling: plasmon to waveguide mode 2.2 dB per facet
click on image to enlarge it

Wide Wavelength range 1520-1590 nm

 

Zoomed near 1545 nm

Note: the fiber-to-fiber transmission includes:

  1. fiber-to-waveguide coupling + Si waveguide loss + waveguide- to- fiber coupling=10 dB.
  2. Plasmon to waveguide-mode coupling
  3. waveguide-mode to plasmon coupling
  4. plasmon propagation loss

TMo mode is excited in AlGAAs waveguide

 

 

Measurements of the fiber-to-fiber transmission for different length of the plasmonic waveguide allows to estimate the plasmon' propagation loss and waveguide-mode/plasmon coupling efficiency

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Under-etched plasmonic waveguide

 

 

Fig.6 Plasmonic waveguide Fe/MgO/AlGaAs integrated with AlGaAs dielectric waveguides.

For confinement out of metal edge, AlGaAs is partiality etched out under metal

click on image to enlarge it

The cross-sectional SEM images of dielectric and plasmonic waveguides are shown.

The field distributions of a waveguide mode and a plasmon are shown in yellow color.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Fiber-to-fiber transmission of the under etched plasmonic waveguide

click on image to enlarge it

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

microscope view of edge of output waveguide

when a plasmon is not excited when a plasmon is excited

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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