1. Liquid Crystal Optical Phased Array (LCOPA)
Xiangru Wang， Liang Wu
Caidong Xiong, Man Li, Shuanghong Wu
Thank~~ Ok，My topic is liquid crystal optical phased array-LCOPA.
Corresponding Author
University of Electronic Science and Technology of China
INEC 2016, Chengdu

2. 1 2 Outline 3 4 Introduction to LCOPA Principle of LCOPA
Our latest milestones 4
Summary
Outline
My content includes 4 parts, XXXX

3. Laser beam steering technologies
Mechanical
机械式
Bulky, complex, expensive
Slow speed
Mechanical inertia
Acousto-optic 声光
Slow speed
Narrow steering range
Low efficiency
Conventional electro-optic
传统的电光
High driving voltage
High insertion loss
Narrow steering range

4. LC Optical Phased Array
液晶光学相控阵
Megapixel
Safe, long life, light
Mass production
Inertialess,no abrasion and vibration
Non-Mech
Low-cost
Pixels
Low driving
Properties
Real-time programmable
Agile scan, high precision
Low SWaP (size weight and power assumption)

5. Agile control technology of laser beam!
Applications of LCOPA
Laser communication
Multiple target designation
Agile control technology of laser beam!
Multi-functional
Laser beam combination

6. Other applications of LCOPA/LCSLM
3D display
Wavelength Selective Switch
H. Gao et al. in Proc. SID, 2012, 59.4.
Robertson, et al. Lightwave Technology 32.3 (2014).
There are some other applications of LCOPA, such as 3D display, wavelength selective switch and optical vortices. ['vɔtɪsiz]
Switchable and Reconfigurable Optical Vortices
Wei Bing, et al. Advanced Materials (2014).

7. 1 2 Outline 3 4 Introduction to LCOPA Principle of LCOPA
Our milestones 4
Summary
Outline
Next, I want to make some introduction of the principle of LCOPA.

8. Principle of optical phased array
Principle of LCOPA 1 2 1 2
Physics of LC Phase shifting
Principle of optical phased array
液晶移
相原理
光学相
控原理

9. Liquid Crystal (LC)
Liquid crystal is one state between crystalline state and isotropic liquid state in a certain range of temperature.
Molecular arrangement have long-range order
Relative location between molecules is irregular
Anisotropy
Fluidity 
流动性
各向异性
长程有序性 晶体
各向同性液体

10. Photoelectrical properties of LC
1.Dielectric anisotropy
介电各向异性
Positive dielectric
Anisotropy LC
Negative dielectric
Anisotropy LC
Refractive index ellipsoid
折射率椭球
2. Refractive index anisotropy
折射率各向异性
When light transmission direction parallel to the
long axis, polarization direction will not change;
When light transmission direction perpendicular to
the long axis, polarization direction has biggest
change.

11. Phase-voltage characteristic
Physics of LC Phase shifting x z
:LC director
:Refractive index of extraordinary beam
:Refractive index of ordinary beam
液晶指向矢
非寻常光折射率
寻常光折射率
Phase-voltage characteristic
curve of device

12. The sketch of LCOPA For transmissive LCOPA on glass Indium-tin-oxide
(ITO)
Alignment layer: to pretilt the LC molecules.
Spacer: a gap supported by a single layer of spacers with a diameter of a few
microns to control the thickness of the LC cell.
Sheet electrode: as a common electrode connects to ground.
Stripe electrodes: as an array of grating electrodes to apply different voltage on every pixel.

13. Physics of optical phased array
Non-deflected beam
Deflected
beam
（LC director） 0V 0V 0V 0V 5V 3V 2V 0V
No driving voltage
Driving voltage
Incident beam
Incident beam

14. Phase-voltage characteristic
The actual work model
 Blazed grating
Applying voltage
Phase-voltage characteristic
curve of device
LCOPA model

15. The actual work model
FFT

16. 1 2 Outline 3 4 Introduction to LCOPA Principle of LCOPA
Our milestones 4
Summary
Outline
Then, let’s look at some of our milestones on LCOPA.

17. LCOPA device developments LCoG (liquid crystal on glass)
Panel Musk
Array size
10mmX10mm
Pixels
1X1920
Mode
transmission
Steering Angle
±6°
Diffraction Efficiency
(zero-order) %
LCOPA

18. LCoS (liquid crystal on silicon)
Future improvements
LCoS (liquid crystal on silicon)
Properties:
Mega-pixels
2-D panel
Reflective
Low threshold

19. LCOPA System LCOPA System LC phased array device computer algorithm
LC driver

20. Experimental setup of beam steering
LCOPA System
LC phased
array device
computer
algorithm
LC driver

21. Beam steering methods of LCOPA
1. variable period grating (VPG)
可变周期光栅
(a) The ideal serrated phase distribution；(b) The discrete phase distribution
Steering angle:
Uniform and continuous beam deflection with high resolution in the realized steering area.

22. Beam steering methods of LCOPA
1. variable period grating (VPG)
Measured steering angle versus desired angle
from 1000μrad to 1400urad
from -400μrad to 400μrad
Steering steep is 20 urad
A linear relationship between measured steering angle and desired steering angle

23. Beam steering methods of LCOPA Very good repeat precision
1. variable period grating (VPG)
Very good repeat precision
Smaller than 3 %
Measured repetition error versus desired steering angle
Measure 30 times of the far-field light spot of the same controlled deflection angle
The RMS values of steering angle less than 3%
Very good repeat precision

24. Beam steering methods of LCOPA
2. Sub-aperture coherence(SAC)
子孔径相干
(a)
(c)
(b)

25. Beam steering methods of LCOPA
2. Sub-aperture coherence(SAC)
More steps
Higher precision
Intensity distribution of SAC far field on different occupation rates

26. Beam steering methods of LCOPA
2. Sub-aperture coherence(SAC)
Lable
Simulation results (urad)
Experiment results (urad)
Deviation
(urad) a
0.0
0.02
1.0 b
1.03
0.89 c
6.25
5.90
0.35
0.78 d
14.75
14.44
0.31
0.68 e
25.00
24.69
0.57 f
31.25
31.54
0.29
0.44 g
37.50
37.89
0.39
0.37 h
43.75
44.81
1.06
0.26 i
50.00
47.68
2.30
0.15 j
49.54
0.46
0.05 k
50.03
0.03
Ultra-high angular resolution less than 5 urad.

27. 1 2 Outline 3 4 Introduction to LCOPA Principle of LCOPA
Our milestones 4
Summary
Outline

28. Summary and Future Research
LCOPA system
Non-mechanical beam steering technology based on
liquid crystal material
Theoretical study, device and system fabrication
LCOPA by LCoS method（liquid crystal on silicon）
Beam steering methods of LCOPA
VPG method can realize beam deflection with the angular resolution in the order of 20 μrad, and the precision is less than 5 μrad (RMS)
SAC method can realize ultra-high angular resolution less than 5 μrad with almost the same precision
Performance improvement methods

29. Thanks to Acknowledgements Prof. Ziqiang Huang Prof. Xiangru Wang
& hard working students:
Liang Wu,Zhenghui,
Guoguo, JingDu, etc
&And co-authors:
Minggang, Man Li, etc
At last, I want to thank xxxx

30. Thank you for your kind listening!