My Research and Inventions

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Dr. Vadym Zayets

Photonics Systems Group,

Research Institute for Advanced Electronics and Photonics,

National Institute of Advanced Industrial Science and Technology (AIST),

Central 2-1, Room D811,
Umezono 1-1-4, Tsukuba,
Ibaraki-ken 305-8568, Japan.


tel: +81-298-61-5426

v.zayets (at symbol)
v.zayets (at symbol)




developed by Vadym Zayets in AIST (Tsukuba, Japan) from 1995 to 2018





Technology 1:

Mach–Zehnder interferometer (top view)

MZ -interferometer made of Si nanowire waveguides with a high transmission and ON/OFF ratio

Fabrication of Si nanowire waveguide, including integrated polarizer, ring resonator and MZ interferometer.

developed from 2012 till 2015

Minimum dimension: 100 nm
Fiber-to-fiber loss: 8 dB
Application:   Photonic Integrated circuits


Details see here and here




Technology 2:

All-metal transistor with 2 hall probes (top view)

FeBTb/Pt nanowire with MgO/Ta/Ru gate. Gate width 70 nm, gap width 70 nm. The gate voltage modulates magnetic anisotropy and domain structure in nanowire. Bottom probe contacts to the gate, top probe contacts gap between gates.

Fabrication of a metallic nanowire with periodically modulated perpendicular magnetic anisotropy (a nanowire with periodical-stripe gate for all-metal transistor)

developed from 2016

nanowire width: 100nm;
gate stripe width 70 nm;
gap width:70 nm;

Application: high-speed transistor for 3D integration  


Details see here





Technology 3:

Cell of Spin-photon memory

(left) Top view. two Fe nanomagnet contacts on top of p-i-n GaAs photodetector. Nanomagnet diameter: 100 nm, Gap 70 nm (right) Cross-section.

Circular -polarized light excites spin-polarized electrons in the photodetector, which are injected into Fe nanomagnet. Spin-transfer torque reverses the magnetization of Fe.

Fabrication of nanomagnet on top of semiconductor p-i-n photo detector with an Ohmic contact.

developed from 2005 till 2010

Minimum diameter: 100 nm

Minimum gap: 40 nm

Application:   Ultra-high speed non-volatile optical memory


Details see here





Technology 4:

Magnetic tunnel junction (MTJ)

(left) reading principle of MTJ (right) top SEM image of fabricated nano -sized MTJ

Fabrication of nanomagnet, nano-sized tunneling magnetic junction (MTJ)

developed from 2010

Minimum diameter: 50 nm

Fabrication method: slimming

Application: High-density memory  





Technology 5:

Integration of a plasmonic waveguide and a Si nanowire waveguide

Top view. (left) serial integration. (right) Parallel integration

Fabrication of low-optical-loss plasmonic waveguides

developed from 2008

Minimum dimension: 50nm

propagation loss: 0.7 dB/um (Fe,Co); 0.09 dB/um (Au);

Application:   Photonic Integrated circuits, optical isolator


Details see here









Technology 6:

Voltage controlled magnetic anisotropy (VCMA)

Top view. (left) top view(right) Change of coercive field under gate voltage

Measurement method for voltage-controlled magnetism in a ferromagnetic nanowire

developed from 2018

Measurement precision:
Voltage-controlled coercive field: 0.5 Oe/V
Voltage-controlled anisotropic field: 30 Oe/V
Voltage-controlled Hall angle:  0.1 mdeg/V

Application:   Magnetic random access memory (MRAM) & all-metal transistor


Details see here

Technology 7:

Phase-locked pump-probe experiment

Setup was used to verify multiplexing speed of spin-photon memory of 2.2 TBit/sec.

Setup of phase-locked pump-probe experiment

developed from 2005 till 2008

Pump-probe delay precision: λ/90

Precision of switching speed measurement: 50 fs

Application:   test of recording speed of high-speed non-volatile optical memory


Details see here





Technology 8:

Fiber-to-waveguide coupling

Top view. (left) top view. Both the fiber-waveguide-camera and fiber-waveguide-fiber setups are used.(right) top view of fiber and waveguides. Light from cleaved edge of waveguide.

Fiber-to-waveguide coupling setup

developed from 2000 till 2002

A magnetic field up to 5 kGauss can be applied along or perpendicular to the waveguide.

Alignment precision: 10 nm

Alignment method: automatic

Application:   Photonic Integrated circuits


Details see here

Technology 9:

magneto transport probe for evaluation of magnetic nanostructures

Top view. Setup to evaluate magneto-transport properties of magnetic nanostructures. Magnetic field can be applied in any direction

High-precision measurements of coercive and anisotropic fields, retention time, energy of magnetic anisotropy and Δ

developed from 2017

Max magnetic field: 7.2 kG out-plane and 2 kG in-plane.

Measurement Precision:

Coercive field: 0.1-0.9 Oe

Anisotropic field: 10 Oe

Unique features:

1. Magnetic field can be applied in any direction

2. High- precision measurements of coercive field

Application: Performance evaluation of MRAM, measurements of VCMA, AMR, TMR & Spin Hall effect  

Details see here

Technology 10:

hybrid isolator

Optical amplifier suppress absorption by Fe. Due to the non-reciprocal absorption by Fe,the device is transparent in the forward direction, but it blocks light in the opposite direction.

Fabricating and testing semiconductor optical amplifier (SOA), semiconductor laser diode (LED) and hybrid amplifier

developed from 1999 till 2005

active region: MQW GaAsP/AlGaAs tensile-strained multi QW

growth method: MBE


Application:   Photonic Integrated circuits


Details see here

Technology 11:

CdMnTe optical isolator

(left) experimental setup to measure magneto-optic effect in CdMnTe waveguide. Light is coupled to waveguide by a prism. Top camera with a polarizer measures properties of a waveguide mode. (right) Under magnetic field, light streak is modulated due to polarization rotation of waveguide mode

Optical isolator made of a diluted magnetic semiconductor

developed from 1995 till 2005

Magneto-optical material: CdMnTe grown on GaAs

Coupling method: prism

Propagation loss: 0.1 dB/mm

Mode conversion ratio: 98%

Isolation: 25 dB

Application:   Photonic Integrated circuits


Details see here



















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