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Integrity Service Excellence

Adaptive

Multimode

Sensing

Date: 07 03 2013

Jim Hwang Program Officer

AFOSR/RTD Air Force Research Laboratory

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2013 AFOSR SPRING REVIEW 3001B PORTFOLIO OVERVIEW

NAME: Jim Hwang BRIEF DESCRIPTION OF PORTFOLIO: Adaptive Multimode Sensing LIST SUB-AREAS IN PORTFOLIO:

I. Adaptive Multimode Sensing – Emphasize tunable detectors and different detection modes such as polarization and phase (in addition to intensity and color). Main challenge: phase detection.

II. Novel Infrared Sensors – Emphasize novel materials and structures such as quantum dots, nano-wires, type-II superlattices, and 3D integration. Main challenge: dark current.

III.Solar Cells, Thermoelectric Coolers & Others – Deemphasize to focus portfolio with reducing budget.

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Motivation Shorten time from sense to kill; avoid drowning in data

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-2 V

S.I. GaAs Substrate

LWIR AlGaAs/GaAs QWIP

NIR AlGaAs/GaAs PIN

-2 V

S.I. GaAs Substrate

LWIR AlGaAs/GaAs QWIP

NIR AlGaAs/GaAs PIN

Near IR LWIR

77 K

3-Color detector demonstrated, too.

Optically-Switched 2-Color Infrared Detector Yong-Hang Zhang (Arizona State) & Elizabeth Steenbergen (AFRL/RXAN)

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Speed/Sensitivity Trade-Off of IR Detectors Vladimir Mitin (Buffalo) & Andrei Sergeev (Buffalo)

Potential barriers around charged InAs quantum dots

(QDs) in GaAs prevents recombination and

prolongs electron lifetime

Charged QDs strongly enhance IR response of

photo-detectors/solar cells

p+ GaAs InAs QDs n+ GaAs

InAs QDs n+ GaAs

n+ GaAs

6 Distribution A: Approved for public release; distribution is unlimited

Electrically Switchable Plasmonic Polarizers Xuejun Lu (Mass-Lowell)

Field distribution (resonance wavelength) can be switched by electrically biasing the polarizer

Rec

tang

ular

Arr

ay o

f A

u Pl

asm

onic

Pol

ariz

ers

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Spectral-Polarization Imaging Viktor Gruev (Washington, St. Louis)

Color Filters Angle of Polarization Image

SEM of Al Nanowires

Si

Si Cone

Polarization Filter

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0 100 200 300 400 500 600 700

0.0

0.1

0.2

0.3

0.4

Pho

tocu

rren

t (µA

)

Time (ns)

x0.3PbS QD

2 nm

(111) planes

(111) planes

0.004 0.006 0.008 0.010 0.012 0.0141E-5

1E-4

1E-3

0.01

0.1250 167 125 100 83 71

1E-1

QD

Dec

ay R

ate

(ns-1

)

1E-2

T (K)

1/T ( K-1)

Non-radiative Energy Transfer

Si

Non-radiative Energy Transfer from Quantum Dots

Anupam Madhukar (S. Cal.), M. Mahalingam (RXAN) & G. Brown (RXAN)

Controlled energy/charge transfer between colloidal nanostructures and conventional semiconductors

Substrate

QD

10−1

10−2

10−3

10−4

10−5 Pho

tolu

min

esce

nce

Dec

ay (/

ns)

Si

9 Distribution A: Approved for public release; distribution is unlimited

Crystalline Bismuth Nanowire Jimmy Xu (Brown)

Bi Pt

Bi Pt

IR/THz Detector

• Bi: only known natural negative index material @ 60um or 5THz

• Bi oxides easily • 1st Bi/Pt heterojunction

successfully grown

10 Distribution A: Approved for public release; distribution is unlimited

InAs/GaSb Type II Superlattices Sanjay Krishna (New Mexico), Vincent Cowan (RVSS), Christian Morath (RVSS) & John Hubbs (RVSS)

Collaboration with Raytheon Vision Systems

• Type II superlattices with antimonides barriers can compete with HgCdTe for infrared sensing

• Strong interests from AFRL (RX, RY, RV), Army NVL, MDA and DARPA

• Enhanced multimodal functionality (color, polarization, dynamic range, phase) through integration with metamaterials

Mid-IR Response @ 420 K!

GaSb

InAs

EC

EV

11 Distribution A: Approved for public release; distribution is unlimited

Single-Crystal Semimetal/Semiconductor Nano-Composites

Chris Palmstrøm (UCSB) & Kurt Eyink (AFRL/RXAN)

Incr

easi

ng E

rSb

com

posi

tion

[001

] ρ˔ ρ//

{110}

GaSb

ErSb

GaSb

ErSb

GaSb (ErSb)x(GaSb)1-x (Semimetal) (Semiconductor)

•ErSb/GaSb nano-composites grown by molecular beam epitaxy

•Buried conductive layers for multicolor infrared detectors

•THz polarizers embedded in III-V heterostructures

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Funding Trend

I. Adaptive Multimode Sensing – Emphasize tunable detectors and different detection modes such as polarization and phase (in addition to intensity and color). Main challenge: phase detection.

II. Novel Infrared Sensors – Emphasize novel materials and structures such as quantum dots, nano-wires, type-II superlattices, and 3D integration. Main challenge: dark current.

III.Solar Cells, Thermoelectric Coolers & Others – Deemphasize to focus portfolio with reducing budget.