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UNCLASSIFIED. Photonic-Crystals In Military Systems Energy Harvesting, Thermal Camouflage, & Directed Energy. 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.

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slide1

UNCLASSIFIED

Photonic-Crystals In Military Systems

Energy Harvesting, Thermal Camouflage, & Directed Energy

Leo DiDomenico3

Hwang Lee1

Marian Florescu1

Irina Puscasu2

Jonathan Dowling1

1 Department of Physics & Astronomy,

Louisiana State University

2 Ion Optics Inc.

3 Xtreme Energetics Inc.

Points of Contact: Dr. Leo D. DiDomenico Leoddd@XEsolar.com & Prof. Jonathan P. Dowling jdowling@lsu.edu

UNCLASSIFIED

slide2

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
slide3

Power Generation Systems:

Low-Temperature

Thermophotovoltaics

Problem

Applications

PBG

Conventional TPV Systems Too Hot

Performance Expectations

Solution

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.

S. Lin et al. Sandia Labs

slide4

Tunable IR

Camouflage Systems

Other Applications

Problem

Thermal signatures have become too easy to detect

  • Improved Thermal Imagers
  • Thermal Camouflage
  • Radar Signature Reduction
  • Low Observability and Stealth
  • Solar and Thermal Covers

Solution

Thermal Radiation Control Designs

  • Engineer the radiative thermal response using photonic crystals to control:
    • Spectral
    • Directional
    • Tunability

for adaptive thermal emissivity response.

  • Omnidirectional IR reflectors
  • Broadband systems
  • Multi Band Operation
  • PBG coatings with surface effects
  • Smart Skin Technology for Tanks
slide5

High-Power

Photonic Crystal Lasers for Power Beaming

Problem

Applications

Defense against kinetic energy weapons requires

repeated fast interception. Chemical lasers fail to

deliver the punch over an extended fight.

  • High power thermally pumped PBG lasers
  • Replace chemical laser
  • Deep ammunition magazine
  • Other -- Point-to-point laser comm.

Solution

Gas Dynamic lasers require energetic chemical reactions which limit practical embodiments

Convert heat gradients into

A flow of incoherent narrow band pump light for laser using PBG energy funnel.

Cold

slide6

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
photonic crystal structures
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
slide8

Simple Photonic Crystals

  • 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)

slide9

3-Dimensional Photonic Crystals

Each scattering site contributes to the total

Wave response.

The math can be very complexbut the basic idea is VERY SIMPLE...

Scattered waves can add destructivelyfor some frequencies and from somedirections…

Therefore, certain very special PBG structures have all directions of propagation forbidden over a band of frequencies.

3D Crystal Structure with scattering plans shown

slide10

New Design Tools are Needed for Opto-Thermal Engineering with Photonic Crystals

2D

1D

  • TDOS measures the number of states {kx, ky, kz, n} that radiate.
  • TDOS is the number of states for a given dw about the frequency w.
  • 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 whereatoms 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.

slide11

Photonic Crystals:

Examples

Butterfly Wing

Opal

Inverted Opal

Silicon Pillars

Photonic Crystal

Fiber

Woodpile

slide12

A Dizzying Array ofPotential Applications

Semiconductors for Light

  • Band Gap:

Optical Switching & Routing

  • Band-Gap Shift:
  • 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

Photodetectors, LED

  • Micro-cavity Effects:

Low-Threshold Lasers

slide13

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
pv cells need a matched spectrum
PV Cells Need a Matched Spectrum

TPV Cell

There are 2 potential solutions Using Photonic Crystals …

Heat Generated!

Out of band energy from PV cell,creates waste heat but no electricity !

method 1 thermal gradients allow rethermalization
Method 1: Thermal Gradients Allow Rethermalization

Heat

Source

Photonic

Crystal

Hot

Cold

Band GapLight Cone

To TPV

RethermalizeOut of Band Energy

thermal radiation in pbg material
Thermal Radiation in PBG Material

RECALL:

Photon-PhononInteraction 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
tpv energy conversion pbg spectral control
TPV Energy Conversion:PBG Spectral Control

TPV Cell Device

Spectral

Funnel(Not a Filter)

Broad BandHeat Source

slide18

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
  • Recycle: Heat the absorber with the unused photons

Incorporate PBG into a Classic TPV Design

method 2 tpv energy conversion using pbg directional control
Method 2: TPV Energy Conversion:Using PBG Directional Control

absorber

cell

Solid angle for absorber

Solid angle for the sun

85%

Temp of the thermal source

Temp of absorber

TA = 2500 K

Temp of the cell

T Kelvin

Instead of increasing WS (concentration), decrease

the solid angle of the intermediate absorber, WA.

Full concentration

slide20

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

2D PBG

1D Channel

3D PBG

funneling of the thermal radiation

Photonic crystal radiation

Blackbody input radiation

Filter output radiation

Filter output radiation

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)

Proposed

Current

5 % Transfer efficiency

20 % Transfer efficiency

Blackbody input radiation

slide22

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
doubly periodic photonic crystals dual band optical properties i
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

doubly periodic photonic crystals dual band optical properties ii
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

dynamical tuning of spectral emissivity
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

slide27

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
energy separation i

Light Spectral Distribution vs Position

Phonons

Hot

Cold

Narrow BandPhotons

Laser GainMedium

Energy Separation - I

Schematic of energy flow:

  • Temperature gradient moves phonons left to right & Rethermalizes.
  • 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.

energy separation ii
Energy Separation - II

Photonic

Crystal

Cold

Designing thespectral and directionalProperties of PCS is ahard synthesis problem.

LasingMedium

Hot

slide30

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
slide31

512 node, dual-processor IA32 Linux cluster with 3.06 GHz Intel Pentium IV Xeon processors and 2 GB RAM

Super- Mike LSU

New, $4.6M, world-class, JEOL JBX-9300FS e-beam lithography system (third of its kind)

MDL JPL

Spectral and angular optical FTIR characterization facilities

Ion Optics Inc.

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

Three-dimensional photonic crystal emitter for thermophotovoltaic power generation, Lin et al.,(2003) Sandia Labs

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

slide32

Funneling of the Thermal RadiationExperimental Results

BB, Pin = 315 mW, T2 = 420.1 oC

BB (273.4oC) and PC (273.4oC) plots have the same input power while the photonic crystal produces lower wavelength photons

PC, Pin = 130 mW, T2 = 420.1 oC

BB, Pin = 130 mW, T1 = 273.4 oC

BB (420.1oC) and PC (273.4oC) 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)

slide33

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.