Transcript Photonic-Crystal Satellite Reflectors and Radiators
UNCLASSIFIED
Photonic-Crystals In Military Systems Energy Harvesting, Thermal Camouflage, & Directed Energy
1
Leo DiDomenico 3 Hwang Lee 1 Marian Florescu 1 Irina Puscasu 2 Jonathan Dowling 1 1 Department of Physics & Astronomy, Louisiana State University 2 Ion Optics Inc.
3 Xtreme Energetics Inc.
Points of Contact: Dr. Leo D. DiDomenico [email protected]
UNCLASSIFIED & Prof. Jonathan P. Dowling [email protected]
Project Summary
Contents
Introduction to Applications of Photonic Band Gap (PBG) Material
What is a Photonic Band Gap Material?
Generating Electricity from Spectral & Directional Control of IR Radiation
Controlling Thermal Radiation for IR Camouflage
Pumping Laser Weapons with Thermal Radiation from PBG Materials
Initial Experimental Studies On PBG Thermal radiation control
Project Summary
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Problem
Power Generation Systems: Low-Temperature Thermophotovoltaics
Applications PBG 3 Conventional TPV Systems Too Hot Solution
P out P in
V
max ( max
d
b s
)
Optimize the input radiation band and propagation direction to a PV & don’t worry too much about the PV itself!
TPV using PBG is relatively Low Temperature.
Performance Expectations
Tunable IR Camouflage Systems
Problem Thermal signatures have become too easy to detect
Other Applications
Improved Thermal Imagers Thermal Camouflage Radar Signature Reduction Low Observability and Stealth Solar and Thermal Covers
Solution
Engineer the radiative thermal response using photonic crystals to control: Spectral Directional Tunability for adaptive thermal emissivity response.
Thermal Radiation Control Designs
Omnidirectional IR reflectors Broadband systems Multi Band Operation PBG coatings with surface effects Smart Skin Technology for Tanks
Project Summary
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High-Power Photonic Crystal Lasers for Power Beaming
Problem Defense against kinetic energy weapons requires repeated fast interception. Chemical lasers fail to deliver the punch over an extended fight. Applications
•
High power thermally pumped PBG lasers
•
Replace chemical laser
•
Deep ammunition magazine
•
Other -- Point-to-point laser comm.
5 Solution Convert heat gradients into A flow of incoherent narrow band pump light for laser using PBG energy funnel.
Cold Gas Dynamic lasers require energetic chemical reactions which limit practical embodiments
Project Summary
Contents
Introduction to Applications of Photonic Band Gap (PBG) Material
What is a Photonic Band Gap Material?
Generating Electricity from Spectral & Directional Control of IR Radiation
Controlling Thermal Radiation for IR Camouflage
Pumping Laser Weapons with Thermal Radiation from PBG Materials
Initial Experimental Studies On PBG Thermal radiation control
Project Summary
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Photonic Crystal Structures
•
Periodic dielectric
•
Scale of periodicity is ~
l
/2.
•
Exhibits large dielectric contrast.
•
Light velocity is a function of direction.
•
Temperature varies slowly relative to ~
l
/2.
•
Thermal radiation is selectively suppressed.
•
“Semiconductor” material for Light
Project Summary
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Simple Photonic Crystals
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Alternating materials of higher & lower refractive indices Periodicity: on the order of wavelength of light Functionality: semiconductors for light Joannopoulos, Meade, Winn,
Photonic Crystals
(1995)
Project Summary
3-Dimensional Photonic Crystals
Each scattering site contributes to the total Wave response.
9 The math can be very complex but the basic idea is VERY SIMPLE...
Scattered waves can add destructively for some frequencies and from some directions… Therefore, certain very special PBG structures have all directions of propagation forbidden over a band of frequencies.
3D Crystal Structure with scattering plans shown
Project Summary
New Design Tools are Needed for Opto-Thermal Engineering with Photonic Crystals
1D 2D 10
•
TDOS measures the number of states {kx, ky, kz, n} that radiate.
•
TDOS is the number of states for a given d
about the frequency
.
•
Opto-Thermal applications require extending the idea of TDOS.
•
The TDOS must be extended to account for the overlap of
The periodic dielectric
The Radiation field.
Atoms with atomic transitions.
Temperature distribution.
The fields do not always overlap the dielectric where atoms can absorb or emit energy & heat the material.
An extension of basic radiation theory, which now includes photon-phonon interactions inside a PBG material with a non-uniform temperature distribution, is being developed by the authors and with the intent of develop engineering software tools for opto-thermal PBG materials.
Project Summary
Photonic Crystals: Examples
Butterfly Wing Opal
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Inverted Opal Silicon Pillars Photonic Crystal Fiber Woodpile
Project Summary
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A Dizzying Array of Potential Applications
Band Gap: Semiconductors for Light Band-Gap Shift: Optical Switching & Routing Local Field Enhancement: Strong Nonlinear Optical Effects Anomalous Group Velocity Dispersion: Negative index metamaterials for stealth applications and super-prism dispersion, true time delay lines Micro-cavity Effects: Photodetectors, LED Low-Threshold Lasers
Project Summary
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Contents
Introduction to Applications of Photonic Band Gap (PBG) Material
What is a Photonic Band Gap Material?
Generating Electricity from Spectral & Directional Control of IR Radiation
Controlling Thermal Radiation for IR Camouflage
Pumping Laser Weapons with Thermal Radiation from PBG Materials
Initial Experimental Studies On PBG Thermal radiation control
Project Summary
PV Cells Need a Matched Spectrum
TPV Cell 14 Heat Generated! There are 2 potential solutions Using Photonic Crystals … Out of band energy from PV cell,creates waste heat but no electricity !
Project Summary
Method 1: Thermal Gradients Allow Rethermalization Heat Source Hot Photonic Crystal Cold Band Gap Light Cone
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Rethermalize Out of Band Energy To TPV
Project Summary
Thermal Radiation in PBG Material
Interaction in Non-PBG Now extend principles to a PBG material
•
Spectral Intensity: position, direction, & frequency
•
Absorptivity: T(r), direction, # of levels, & frequency
•
Energy velocity depends on PCS
•
Total density of atom-connected photon states
Project Summary
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TPV Energy Conversion: PBG Spectral Control
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Broad Band Heat Source Spectral Funnel (Not a Filter) TPV Cell Device
Project Summary
TPV Energy Conversion State-of-the-art
Improve conversion efficiency: Recycling the unused photons to heat the Emitter/absorber • Intermediate Absorber/Emitter • Filter: Only the photons with right energy • Keep operating temperatures lower
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• Recycle: Heat the absorber with the unused photons
Method 2: TPV Energy Conversion: Using PBG Directional Control
0.8
0.6
0.4
85% 0.2
T A = 2500 K 1000 2000 3000 T Kelvin 4000 Full concentration 5000
S
6000
TPV
1
S A T A
4
T s
4 1
T T A
0 absorber cell
S A
Solid angle for absorber Solid angle for the sun
T S T A T
0 Temp of the thermal source Temp of absorber Temp of the cell Instead of increasing S (concentration), decrease the solid angle of the intermediate absorber, A .
Project Summary
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Novel PBG Angle-Selective Absorber
Novel Design of an efficient angle-selective PBG absorber
• a wave-guide channel in 2D PBG embedded in a 3D PBG structure • single-mode (uni-directional) operation for a wide range of frequency • alternative structures can be designed to achieve a prescribed efficiency • LSU patent application
3D PBG 20 2D PBG 1D Channel 3D PBG
Project Summary
Funneling of the Thermal Radiation
• For a given blackbody input power, T= 400 K (area under the red curve) – Filter • only eliminates lower and higher spectral components, selecting incident radiation in a narrow range • Appreciable amount of energy is wasted – Photonic crystal • funnels the incident energy into a narrow spectral range • runs at a higher effective temperature (defined by the blackbody with the same maximum peak power) Current Proposed
Photonic crystal radiation
W
5 % Transfer efficiency
W
20 % Transfer efficiency
21 Blackbody input radiation Blackbody input radiation Filter output radiation Filter output radiation
Project Summary
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Contents
Introduction to Applications of Photonic Band Gap (PBG) Material
What is a Photonic Band Gap Material?
Generating Electricity from Spectral & Directional Control of IR Radiation
Controlling Thermal Radiation for IR Camouflage
Pumping Laser Weapons with Thermal Radiation from PBG Materials
Initial Experimental Studies On PBG Thermal radiation control
Project Summary
Hiding Thermal Signatures
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Project Summary
Doubly-Periodic Photonic Crystals: Dual-Band Optical Properties (I)
“On demand” optical transmission and reflection spectra
three characteristic length scales: radius of the cylinders, distance between the cylinders and width of the rectangular veins (optimum values: r/a=0.078, L/a=0.194 and w/a=0.38) full photonic band gap (both polarizations) of / c =18.25% centered on c / 0 =0.83
presents spectral regions with high reflection concomitant with a large number of modes at lower frequencies (high transmission)
Photonic crystal structure Photonic band structure 24
Project Summary
Doubly-Periodic Photonic Crystals: Dual-Band Optical Properties (II)
“On demand” field distribution depending on the frequency the field can be localized in different regions of the high-index of refraction dielectric or in the air fraction spatial field distribution can be used to optimize the coupling to absorbers placed into the structure in order to enhance thermal emission
Electromagnetic field distribution for TM modes for the first three bands at the M-point 25
Project Summary
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Dynamical Tuning of Spectral Emissivity
Normalized emission from photonic crystal test structure at 325 C under different gas conditions: different concentration values for CO2 and N2. (right side-zoom in) Possibility of tuning the emissivity of the structure by gas choice and by controlling its gas concentration 0.25
0.20
0.15
0.10
Baselinenog C-10 C-12.5
C-15 C-2.5
C-20 C-5 N2-a N2-b N2-c N2-d N2-e N2purge 0.05
0.00
3.9
4.0
4.1
4.2
4.3
4.4
wavelength (microns) 4.5
4.6
4.7
Project Summary
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Contents
Introduction to Applications of Photonic Band Gap (PBG) Material
What is a Photonic Band Gap Material?
Generating Electricity from Spectral & Directional Control of IR Radiation
Controlling Thermal Radiation for IR Camouflage
Pumping Laser Weapons with Thermal Radiation from PBG Materials
Initial Experimental Studies On PBG Thermal radiation control
Project Summary
Energy Separation - I
Light Spectral Distribution vs Position 28 Phonons Hot Cold Narrow Band Photons Laser Gain Medium
Schematic of energy flow: 1.
Temperature gradient moves phonons left to right & Rethermalizes.
2.
Photonic Band Gap restricts photons to move downward.
Three types of insulators are possible: electrical, thermal, & light. We are using the light insulating properties of Photonic Crystals to force the desired narrow-band photons into the Lasing gain medium & rethermalizing the remaining out-of-band photons into the desired band for further extraction.
Project Summary
Lasing Medium Energy Separation - II Photonic Crystal Hot Cold
Designing the spectral and directional Properties of PCS is a hard synthesis problem.
Project Summary
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Contents
Introduction to Applications of Photonic Band Gap (PBG) Material
What is a Photonic Band Gap Material?
Generating Electricity from Spectral & Directional Control of IR Radiation
Controlling Thermal Radiation for IR Camouflage
Pumping Laser Weapons with PBG & Thermal Radiation
Initial Experimental Studies On PBG Thermal radiation control
Project Summary
Photonic Crystals: Thermal Radiation Control in IR
Enhancement and suppression of thermal emission by a three dimensional photonic crystal, Lin et al. (2000) Sandia Labs Photonic-crystal enhanced narrow-band infrared emitters, Pralle et al. (2002) Ion Optics
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512 node, dual-processor IA32 Linux
Three-dimensional photonic crystal emitter for thermophotovoltaic power generation, Lin et al.,
Xeon processors and 2 GB RAM
(2003) Sandia Labs
LSU Spectral and angular optical FTIR characterization facilities Ion Optics Inc.
Thermal emission and absorption of radiation in finite inverted-opal photonic crystals, Florescu et al., (2005) JPL&LSU Direct calculation of thermal emission for three-dimensionally periodic photonic crystal slabs, Chan et al.
(2006) MIT
Project Summary
Funneling of the Thermal Radiation Experimental Results
BB (273.4
o C) and PC (273.4
o C) plots have the same input power while the photonic crystal produces lower wavelength photons
BB, P in = 315 mW, T 2 = 420.1 o C PC, P in = 130 mW, T 2 = 420.1 o C BB, P in = 130 mW, T 1 = 273.4 o C
BB (420.1
o C) and PC (273.4
o C) plots have the same peak power wavelength – Funneling of thermal radiation of larger wavelength (orange area) to thermal radiation of shorter wavelength (grey area).
JPL (micro-fab), Ion Optics (testing), LSU (analysis)
Project Summary
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Conclusions
TPV cell efficiencies can be dramatically improved by employing the spectral and angular control provided by photonic crystals
Dual-band spectral radiation management systems using doubly periodic photonic crystals are now being designed using a restricted set of “practical” structures
Experimental results confirm the photonic crystal ability to control the thermal radiation properties
New vistas exist for using photonic crystals in lasers, IR thermal signature suppression, and high-power ( non-chemical ) lasers for communications and weapons.
Project Summary
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