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Laser stimulated broadbandemission of graphene
Online Symposium „Functional Coatings, Manufacturing, Methodology & Application”, 9 March 2021
Wiesław Stręk
Institute of Low Temperature and Structure ResearchPolish Academy of Sciences
Graphene foam emission
80 100 120 140 160 180 200
3
4
5
6
0.01 0.1 1 0.01 0.1 1 0.01 0.1 1 0.01 0.1 1
400 500 600 700 800 900
N
1/r2 [1/cm
2]
N = 3.02
a
Inte
nsity [a.u
.]
Power [W]
(a)N = 6.11N = 4.22
b
(b)
Inte
nsity [a.u
.]
Power [W]
N = 4.74
c
(d)(c)
Inte
nsity [a.u
.]
Power [W]
d
Inte
nsity [a.u
.]
Power [W]
0.01032 0.00838 0.00672 0.00532spot area [cm
2]
(f)
inte
nsity [
a.u
.]
wavelength [nm]
(e)
Online Symposium „Functional Coatings, Manufacturing, Methodology & Application”, 9 March 2021
Graphene foam emission
Photocurrent measurements
Temporal change in the sample resistivity
Single turn on/turn off resistance changes
Online Symposium „Functional Coatings, Manufacturing, Methodology & Application”, 9 March 2021
Graphene foam emission
Photocurrent measurements + hot electrons generationApplied electric field influence
Online Symposium „Functional Coatings, Manufacturing, Methodology & Application”, 9 March 2021
Graphene foam emission
Visible and NIR broadband emission
400 500 600 700 800 900
0
500
1000
1500
1000 1200 1400 1600 1800 2000 2200 24000
1000
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23000
24000
25000
inte
nsity (
arb
. u.)
wavelength (nm)
lexc = 975 nm
inte
nsity (
arb
. u.)
wavelength (nm)
rexc = 7000 W/cm2
Online Symposium „Functional Coatings, Manufacturing, Methodology & Application”, 9 March 2021
Coherence of LIWE on Graphene
Graphene bulb
without exc exc 975 nmInterference
exc 975 nm exc 808 nm
Online Symposium „Functional Coatings, Manufacturing, Methodology & Application”, 9 March 2021
Coherence of LIWE on Graphene
Measurement setupThe registered interference
Registered fringes with and without spectral filter
Online Symposium „Functional Coatings, Manufacturing, Methodology & Application”, 9 March 2021
Coherence of LIWE on Graphene
• a point-like white light source with a high degree of spatial coherence
• a possibility to obtain a collimated beam of white light with low divergency angle
Point-like source of white light based on graphene excited by a CW laser
Layout of a light source producing broadband collimated beam
Online Symposium „Functional Coatings, Manufacturing, Methodology & Application”, 9 March 2021
LIWE mechanism
Inversion of population
Coherence
White laser???
Online Symposium „Functional Coatings, Manufacturing, Methodology & Application”, 9 March 2021
Broadband fiber light source
• point-like emission area matching the core size of a typicalmultimode fiber
Layout of a potential bradband fiber light source
Online Symposium „Functional Coatings, Manufacturing, Methodology & Application”, 9 March 2021
Broadband fiber light source
Insights
• emissivity depends on morphology, porous structure of graphene foam is an advantage
• emissivity higher than for an electric lamp with tungsten filament
• decay of light power over time
Online Symposium „Functional Coatings, Manufacturing, Methodology & Application”, 9 March 2021
Hydrogen generation
Other application of ionization of graphene surface by laser
The generation of hydrogen from alcoholes and water
Online Symposium „Functional Coatings, Manufacturing, Methodology & Application”, 9 March 2021
Thank you for attention !
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