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72 UEC Int’l Mini-Conference No.52

UEC International Mini-Conference No.52
Electron Beam Fabrication of Phase Hologram
Tonmoy Hasan CHOWDHURY , Yoko MIYAMOTO
*
* Department of Engineering Science, the University of Electro-Communications
* Institute for Advanced Science, the University of Electro-Communications
1-5-1 Chofugaoka, Chofu, Tokyo, 182-8585, Japan
Keywords: Electron beam fabrication, optical vortex array, phase hologram, classical and quantum information communication.
Objectives:
1. Fabricate phase hologram using an electron beam fabrication process.
2. Evaluate the fabricated hologram and observe the intensity distribution of diffracted light.
3. Relate to the proposed research theme.
Background
ü A hologram is an optical element that modifies the incident light's phase and/or amplitude distributions. We aim to fabricate the
phase-only holograms using the electron beam fabrication technique on a polymer layer on a glass substrate.
üThe phase of the incident light can be modified by a reflecting surface with varying heights. This can be achieved by writing
patterns on an electron-beam resist, developing, and coating with metal.
üAccurate modification of phase depends on accurate fabrication of height. To achieve this we need precise data on how electron
dose translates to the fabrication depth of the polymer.
Fabrication of Hologram Holographic pattern
1. Glass Substrate Formation:
ü Cleaning in an ultrasonic cleaner with Ethanol & Acetone,
ü Coating with transparent conducting material (ITO)
ü Spin-coating with electron-beam resist polymer (gL1000-5).
ü Bake at 180℃ for 3 minutes to make the coating permanent. (i) (ii) (iii)
2. Pattern: Figure 2: (i) Electron dosed for 4.25µs
ü Create the desired pattern with MATLAB. (ii) Electron dosed for 3.75µs (iii) Electron dosed for 2.15µs
3. Fabrication:
ü Depending on the pattern dose electrons multiple times.
4. Development:
ü Develop the fabricated glass substrate with a developer solution
and need to clean with water.
ü Finally, coat with metal (gold) to make the substrate reflective. (i) (ii)
Figure 3: (i) Blazed structure of fabricated phase hologram
(ii) The gradient of phase singularity from (0,2]
Result Evaluation

2mm
Figure 1: Fabrication and development of hologram
Future Plan 2mm
Figure 6: Microscopic view of phase hologram
As a future aspect, my goal is to create Dammann optical vortex
grating to generate a uniformly bright optical array using the electron
beam fabrication method. And then establish a multiplexing-
demultiplexing system to use the diffracted array in classical and
quantum information communication.

= 7 = 1 (, ) = (7, 1)
(i) (ii) (iii)
Figure 5: (i) Dammann grating for the charge of phase singularity=7
(ii) Dammann grating for the charge of phase singularity=1
(iii) 2-dimensional Dammann diffraction grating Figure 4: Observed optical vortex array
Reference
Conclusion [1] Yoko Miyamoto, Mitsutoshi Masuda, Atsushi Wada, and Mitsuo
Using the electron beam fabrication process we can achieve an optical vortex Takeda; “Electron-beam lithography fabrication of phase holograms to
array of multiple spots with equal intensity distribution. As a future aspect, a generate Laguerre-Gaussian beams”; Part of the OSJ/SPIE Conference
multiplexing-demultiplexing system needs to be established to use the optical on Optical Engineering for Sensing and NanotechnoloQy 232 (ICOSN
'99); Yokohama, Japan. June 1999; SPIE Vol. 3740. 0277-786X/99
vortex array in classical and quantum information communication.
*The author is supported by (AiQuSci) MEXT scholarship.