Effective Light Beam Modulation by Chirp IDT on a Suspended LiNbO<sub>3</sub> Membrane for 3D Holographic Displays
An acousto-optic (AO) holographic display unit based on a suspended waveguide membrane was developed. The AO unit consists of a wide bandwidth chirp interdigital transducer (IDT) on a 20 µm thick suspended crystalline 128° YX LiNbO<sub>3</sub> membrane, a light blocker...
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2020-02-01
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doaj-f66d407f99a34e26b1f2985238af05fe2020-11-25T01:19:53ZengMDPI AGSensors1424-82202020-02-01204121810.3390/s20041218s20041218Effective Light Beam Modulation by Chirp IDT on a Suspended LiNbO<sub>3</sub> Membrane for 3D Holographic DisplaysYongbeom Lee0Keekeun Lee1Depart. of Electrical & Computer Eng., Ajou Univ., Suwon, Geonggi-do 16449, KoreaDepart. of Electrical & Computer Eng., Ajou Univ., Suwon, Geonggi-do 16449, KoreaAn acousto-optic (AO) holographic display unit based on a suspended waveguide membrane was developed. The AO unit consists of a wide bandwidth chirp interdigital transducer (IDT) on a 20 µm thick suspended crystalline 128° YX LiNbO<sub>3</sub> membrane, a light blocker with a 20 µm hole near the entrance, and an active lens near the exit. The 20 µm thickness of the floating membrane significantly enhanced surface acoustic wave (SAW) confinement. The light blocker was installed in front of the AO unit to enhance the coupling efficiency of the incident light to the waveguide membrane and to remove perturbations to the photodetector during measurement at the exit region. The active lens was vertically attached to the waveguide sidewall to collect the diffracted beam without loss and to modulate the focal length in free space through the applied voltage. As SAWs were radiated from the IDT, a Bragg grating with periodic refractive indexes was formed along the waveguide membrane. The grating diffracted incident light. The deflection angle and phase, and the intensity of the light beam were controlled by the SAW frequency and input power, respectively. The maximum diffraction efficiency achieved was approximately 90% for a 400 MHz SAW. COMSOL simulation and coupling of mode modeling were performed to optimize design parameters and predict device performance.https://www.mdpi.com/1424-8220/20/4/1218acousto-opticwaveguidesurface acoustic wavebragg diffractionactive lensholographic display |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Yongbeom Lee Keekeun Lee |
spellingShingle |
Yongbeom Lee Keekeun Lee Effective Light Beam Modulation by Chirp IDT on a Suspended LiNbO<sub>3</sub> Membrane for 3D Holographic Displays Sensors acousto-optic waveguide surface acoustic wave bragg diffraction active lens holographic display |
author_facet |
Yongbeom Lee Keekeun Lee |
author_sort |
Yongbeom Lee |
title |
Effective Light Beam Modulation by Chirp IDT on a Suspended LiNbO<sub>3</sub> Membrane for 3D Holographic Displays |
title_short |
Effective Light Beam Modulation by Chirp IDT on a Suspended LiNbO<sub>3</sub> Membrane for 3D Holographic Displays |
title_full |
Effective Light Beam Modulation by Chirp IDT on a Suspended LiNbO<sub>3</sub> Membrane for 3D Holographic Displays |
title_fullStr |
Effective Light Beam Modulation by Chirp IDT on a Suspended LiNbO<sub>3</sub> Membrane for 3D Holographic Displays |
title_full_unstemmed |
Effective Light Beam Modulation by Chirp IDT on a Suspended LiNbO<sub>3</sub> Membrane for 3D Holographic Displays |
title_sort |
effective light beam modulation by chirp idt on a suspended linbo<sub>3</sub> membrane for 3d holographic displays |
publisher |
MDPI AG |
series |
Sensors |
issn |
1424-8220 |
publishDate |
2020-02-01 |
description |
An acousto-optic (AO) holographic display unit based on a suspended waveguide membrane was developed. The AO unit consists of a wide bandwidth chirp interdigital transducer (IDT) on a 20 µm thick suspended crystalline 128° YX LiNbO<sub>3</sub> membrane, a light blocker with a 20 µm hole near the entrance, and an active lens near the exit. The 20 µm thickness of the floating membrane significantly enhanced surface acoustic wave (SAW) confinement. The light blocker was installed in front of the AO unit to enhance the coupling efficiency of the incident light to the waveguide membrane and to remove perturbations to the photodetector during measurement at the exit region. The active lens was vertically attached to the waveguide sidewall to collect the diffracted beam without loss and to modulate the focal length in free space through the applied voltage. As SAWs were radiated from the IDT, a Bragg grating with periodic refractive indexes was formed along the waveguide membrane. The grating diffracted incident light. The deflection angle and phase, and the intensity of the light beam were controlled by the SAW frequency and input power, respectively. The maximum diffraction efficiency achieved was approximately 90% for a 400 MHz SAW. COMSOL simulation and coupling of mode modeling were performed to optimize design parameters and predict device performance. |
topic |
acousto-optic waveguide surface acoustic wave bragg diffraction active lens holographic display |
url |
https://www.mdpi.com/1424-8220/20/4/1218 |
work_keys_str_mv |
AT yongbeomlee effectivelightbeammodulationbychirpidtonasuspendedlinbosub3submembranefor3dholographicdisplays AT keekeunlee effectivelightbeammodulationbychirpidtonasuspendedlinbosub3submembranefor3dholographicdisplays |
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1725136740813897728 |