基于铌酸锂光子晶体热释电效应的集成温度传感器的研究_暨南大学_卢惠辉

fragile
5/20/2013 14
Optical characterization
Enhancement of pyroelectric effect inside the PhC cavity Temperature sensing : ~0.36nm/°C Simulation:
Appl. Phys. Lett. 2013 (submitted)
Optimization:
High Q to achieve sensible sensor: temperature or ultra-weak electric filed « Mind Reading »
5/20/2013
18
Acknowledgements CNRS, Femto-ST Institut, France
5/20/2013 1
OutlineDesign and Fabrication
---Characterization ---Conclusion
5/20/2013 2
Introduction
lithium niobate: LN
Nonlinear material, e.g, electro-optic, acousto-optic, pyroelectric, piezoelectric, etc. Transparency from 420 nm to 5200 nm Electro-optic effect is mostly utilized. X-cut wafers:
---Precision in the order of several nm is challenging
5/20/2013 8
Theoretical study and simulation
Slow light and local field factor ---Enhancement of the electro-optic effect
5/20/2013
VgBulk V
PhC g


PhC
PhC Elocal dxdydz
Bulk
E
Bulk local
dxdydz
~ 3
f el :
~ 2
9
Razzari et al, Appl. Phys. Lett. 86, (2005)
Best possible waveguiding configuration in LN (optical guided mode has an optimum interaction with the PhC)
Temperature sensing via an enhanced pyroelectric in lithium niobate photonic crystal structure
卢惠辉 thuihuilu@ 暨南大学光电工程系 Jinan University CNRS Femto-ST Institut, France
5/20/2013 15
Suspended LN waveguide with PhC
Pyroelectric effect:
Ez is the electric field generated by the pyroelectric effect, this electric field depends on the temperature variation. Pyroelectric coefficient ( p = 6x10-5 C m-2 K-1) LN εr = 28.7,
EO in PhC:
Spectral shift
5/20/2013 16
Suspended LN waveguide with PhC Comparisons
Type of sensor (based technology) Long-period FBG Fiber High birefringence fiber-loop mirrors Surface Plasmon resonance within selectively coated PCF Alcohol-filled PCF with loop mirror Dielectric-loaded plasmonic waveguide-ring resonators Intergrated ring resonator in Si Suspended waveguide +PhC in LN sensibility (nm/°C) 0.6 0.94 0.72 6.6 0.01 0.083 ~0.36 interaction length (mm) 1 720 5 61 ~0.007 0.004 (radius) ~0.006
Ultimate guiding geometry & light confinement ---Suspended membrane
3D-FDTD Simulation
Suspended section: Width: 6 mm Depth: 2 mm a =557nm r/a=0.3
5/20/2013
With air window: transmission (78%) Wihtout air window: transmission (13%)
10
PECS-10th, 2012 Santa Fe
Suspended LN waveguide with PhC
E field distribution
ANR project “ANR-09-NANO” France
ORC University of Southampton, UK
5/20/2013
19
Extraordinary refractive index (1550nm) ne = 2.138
r33 = 30.8pm/V
500 mm thick
5/20/2013
3
Optical waveguides of LN
APE(annealed proton exchange)
ne = 2.143
5/20/2013
17
Conclusion: Ultimate light confinement has been successfully introduced by the fabrication of an air suspended LN membrane
---Compact pyroelectric device for temperature sensing ---Sensitivity of ~ 0.36nm/°C ---Interaction length of ~ 6mm
Fabrication steps of a SiO2 mask
Proton Exchange: 80minutes, 180°C
LiNbO3 xH HxLi1 x NbO3 xLi
Exp (optical mode)
Annealing time: 6h at 333°C
5/20/2013
5/20/2013
Courjal et al, J. Phys. D: Appl. Phys. 44 (2011)
5
modulator
Tunable laser
Nanowire cavity
-11 -13
-15
-17 -19 -21 1450 1500 1550 1600 1650
Wavelength (nm)
Ti-indiffused
APE waveguide
Ridge waveguide ( Optical grade dicing or RIE etching)
ridge waveguide + APE
Combine the APE and the Ridge technologies to make the optical mode approach to surface of the waveguide
Sensors and Actuators B 119 (2006) Appl. Opt. 44, (2005) Appl. Opt. 51, (2012) Opt. Lett., 36, (2011) Sensors, 11, (2011) Opt. Exp. 18, (2010) Appl. Phys. Lett. 2013 (submitted)
Nano Letters 11, 3 (2011) 1009-1013 OE 18(15), 15964-15974 (2010)
5/20/2013 7
Fabrication of PhC in LN waveguide
---Well-known material’s strong etch resistance
4
Optical waveguides of LN
Conventional LN waveguide : Ti (titanium) in-diffusion or (APE) Calculation of optical mode (Courjal et al )
low contrast refractive index
Focused Ion Beam (FIB)
Lacour et al, Opt. Mat. 27, (2005)
Air holes of the photonic crystal are made by FIB milling ---Aspect ratio (depth/width): ~ 3 ---Cylindro-conical shape after fabrication by FIB milling (redeposition effect)